v3.22.4
Note 7 - Stock-based Compensation (Details Textual)
$ / shares in Units, $ in Thousands
1 Months Ended 3 Months Ended 12 Months Ended
Jun. 11, 2020
shares
Dec. 31, 2015
USD ($)
shares
Oct. 31, 2022
USD ($)
$ / shares
shares
Feb. 28, 2022
USD ($)
$ / shares
shares
Feb. 28, 2021
USD ($)
$ / shares
shares
Jul. 31, 2020
USD ($)
$ / shares
shares
Feb. 29, 2020
USD ($)
$ / shares
shares
Feb. 28, 2019
USD ($)
$ / shares
shares
Oct. 31, 2018
USD ($)
$ / shares
shares
Dec. 31, 2013
$ / shares
shares
Mar. 31, 2022
Dec. 31, 2022
USD ($)
$ / shares
shares
Dec. 31, 2021
USD ($)
$ / shares
shares
Dec. 31, 2020
USD ($)
$ / shares
shares
Dec. 31, 2019
USD ($)
shares
Nov. 13, 2014
shares
Share Price (in dollars per share) | $ / shares       $ 393.16 $ 374.57             $ 353.61        
Proceeds, Issuance of Shares, Share-Based Payment Arrangement, Excluding Option Exercised | $                       $ 5,358 $ 17,322 $ 18,767    
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)                       1,001,000 411,000 703,000    
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares                       $ 215.63 $ 357.49 $ 175.12    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares)                       837,000 972,000 1,623,000    
Share-based Payment Arrangement, Expense | $                       $ 160,992 $ 123,479 $ 85,551    
Proceeds from Stock Plans | $                       5,877 4,670 3,819    
Restricted Stock Units (RSUs) [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Vested | $                       336,800 381,200 326,200    
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding | $                       939,500        
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | $                       $ 218,800        
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)                       2 years        
Proceeds, Issuance of Shares, Share-Based Payment Arrangement, Excluding Option Exercised | $                       $ 5,400 $ 17,300 $ 18,800    
Time-Based RSUs [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)                       49,000 46,000 76,000    
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares                       $ 390.89 $ 384.33 $ 189.28    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares)                       61,000 71,000 86,000    
Time-Based RSUs [Member] | Employees [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)                       4 years        
Time-Based RSUs [Member] | Director [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       1 year               1 year        
PSU 2022 [Member]                                
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | $     $ 102,800                          
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options (in dollars per share) | $ / shares       $ 30                        
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares       $ 393.16                        
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year)       4 years                        
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate       44.60%                        
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate       1.50%                        
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate       0.80%                        
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions       10.30%                        
PSU 2022 [Member] | Executive Officer [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)       81,000                        
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed       300.00%                        
PSU 2022 [Member] | Executive Officer [Member] | Vesting First Quarter of 2023 if Performance Conditions are Met [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage       50.00%                        
PSU 2022 [Member] | Non-Executive Employees [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)       14,000                        
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average (Year)                     2 years          
Maximum Stock Compensation Costs | $       $ 142,700                        
PSU 2022 [Member] | Non-Executive Employees [Member] | Minimum [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed       200.00%                        
PSU 2020 [Member]                                
Share Price (in dollars per share) | $ / shares             $ 182.62                  
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options (in dollars per share) | $ / shares             30                  
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares             $ 182.62                  
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year)             2 years                  
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate             33.60%                  
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate             1.40%                  
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate             1.10%                  
PSU 2020 [Member] | Executive Officer [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)             100,000           300,000      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed             300.00%                  
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average (Year)             2 years                  
Maximum Stock Compensation Costs | $             $ 51,100                  
PSU 2020 [Member] | Executive Officer [Member] | Vesting First Quarter of 2022 if Performance Conditions are Met [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage             50.00%                  
PSU 2020 [Member] | Non-Executive Employees [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)             30,000           71,000      
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average (Year)       2 years     2 years                  
Maximum Stock Compensation Costs | $       $ 12,600     $ 12,100                  
PSU 2020 [Member] | Non-Executive Employees [Member] | Minimum [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed       200.00%     200.00%                  
PSU 2020 [Member] | Non-Executive Employees [Member] | Maximum [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed       300.00%     300.00%                  
PSU 2020 [Member] | Non-Executive Employees [Member] | Vesting First Quarter of 2021 if Performance Conditions are Met [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage       50.00%     50.00%                  
PSU 2020 [Member] | Non-Executive Employees [Member] | Annual or Quarterly Vesting of Awards Not Based on Performance [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year)       2 years     2 years                  
PSU 2021 [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options (in dollars per share) | $ / shares         30                      
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share) | $ / shares         $ 374.57                      
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year)         4 years                      
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate         41.40%                      
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate         0.30%                      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate         0.60%                      
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions         9.80%                      
PSU 2021 [Member] | Executive Officer [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)         80,000             20,000        
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed         300.00%                      
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average (Year)         2 years                      
Maximum Stock Compensation Costs | $         $ 114,400                      
PSU 2021 [Member] | Executive Officer [Member] | Vesting First Quarter of 2023 if Performance Conditions are Met [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)         240,000                      
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage         50.00%                      
PSU 2021 [Member] | Non-Executive Employees [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)         14,000                      
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average (Year)         2 years                      
Maximum Stock Compensation Costs | $         $ 12,200                      
PSU 2021 [Member] | Non-Executive Employees [Member] | Minimum [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed         200.00%                      
PSU 2021 [Member] | Non-Executive Employees [Member] | Maximum [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed         300.00%                      
PSU 2021 [Member] | Non-Executive Employees [Member] | Vesting First Quarter of 2021 if Performance Conditions are Met [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)         33,000                      
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage         50.00%                      
MPSUs 2020 [Member]                                
Share Price (in dollars per share) | $ / shares                         $ 248.71      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed           500.00%                    
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year)                         4 years      
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate                         38.80%      
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate                         0.20%      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate                         0.80%      
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions                         8.90%      
Share-based Compensation Arrangement by Share-based Payment Award, Number of Price Targets           5                    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period (in shares)                           221,000    
Share-based Payment Arrangement, Expense | $           $ 42,100                    
MPSUs 2020 [Member] | Minimum [Member]                                
Share Based Compensation Arrangement By Share Based Payment Award, Stock Price Target (in dollars per share) | $ / shares           $ 260                    
MPSUs 2020 [Member] | Maximum [Member]                                
Share Based Compensation Arrangement By Share Based Payment Award, Stock Price Target (in dollars per share) | $ / shares           $ 300                    
MPSUs 2020 [Member] | Vest on July, 2023 [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage           75.00%                    
MPSUs 2020 [Member] | Vest on July 20, 2024 [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage           25.00%                    
MPSUs 2020 [Member] | Executive Officer [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)           43,000                    
MPSUs 2020 [Member] | Key Employees [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)           2,000                    
PSU 2019 [Member]                                
Share Price (in dollars per share) | $ / shares               $ 130.67 $ 108.43              
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options (in dollars per share) | $ / shares               $ 30                
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year)               2 years 7 months 6 days 2 years 10 months 24 days              
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate               29.00% 28.70%              
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate               2.50% 2.90%              
PSU 2019 [Member] | Executive Officer [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)               151,000           454,000    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed               300.00%                
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average (Year)               2 years                
Maximum Stock Compensation Costs | $               $ 46,600                
PSU 2019 [Member] | Executive Officer [Member] | Vesting First Quarter of 2023 if Performance Conditions are Met [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage               50.00%                
PSU 2019 [Member] | Non-Executive Employees [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)                 53,000       100,000      
Share-based Compensation Arrangement by Share-based Payment Award, Vesting, Measurement Period of Relative Revenue Growth Rate to Industry Average (Year)                 2 years              
Maximum Stock Compensation Costs | $                 $ 8,100              
Share-based Compensation Arrangement by Share-based Payment Award, Price Per Share Payable Upon Vesting of Equity Instruments Other than Options (in dollars per share) | $ / shares                 $ 30              
PSU 2019 [Member] | Non-Executive Employees [Member] | Minimum [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Minimum Percentage Allowed                 200.00%              
PSU 2019 [Member] | Non-Executive Employees [Member] | Maximum [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed                 300.00%              
PSU 2019 [Member] | Non-Executive Employees [Member] | Vesting First Quarter of 2023 if Performance Conditions are Met [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage                 50.00%              
MSUs 2022 [Member]                                
Share Price (in dollars per share) | $ / shares     $ 342.16 $ 393.16                        
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)     159,000                          
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed     500.00% 500.00%                        
Maximum Stock Compensation Costs | $     $ 119,200 $ 31,300                        
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term (Year)     3 years                          
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate     54.00% 39.00%                        
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate     4.40% 1.70%                        
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Dividend Rate     0.90% 0.80%                        
Share-based Compensation Arrangement by Share-based Payment Award, Number of Price Targets       5                        
Share-Based Payment Arrangement, Plan Modification, Incremental Cost | $     $ 16,400                          
Total number of performance conditions       6                        
MSUs 2022 [Member] | Minimum [Member]                                
Market Awards Price Targets (in dollars per share) | $ / shares     $ 455 $ 472                        
MSUs 2022 [Member] | Maximum [Member]                                
Market Awards Price Targets (in dollars per share) | $ / shares     $ 591 $ 590                        
MSUs 2022 [Member] | Share-Based Payment Arrangement, Tranche One [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Number of Price Targets     5                          
MSUs 2022 [Member] | Executive Officer [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)       24,000                        
MSUs 2018 [Member]                                
Share Price (in dollars per share) | $ / shares                 $ 108.43              
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)                             600,000  
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed                 500.00%              
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate                 31.60%              
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate                 3.00%              
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions                 8.70%              
Share-based Compensation Arrangement by Share-based Payment Award, Number of Price Targets                 5              
Share-based Payment Arrangement, Expense | $                             $ 39,100  
Share-based Compensation Arrangement by Share-based Payment Award, Post-Award Vesting Period, Restriction Period on Sales (Year)                 2 years              
MSUs 2018 [Member] | Minimum [Member]                                
Market Awards Price Targets (in dollars per share) | $ / shares                 $ 140              
MSUs 2018 [Member] | Maximum [Member]                                
Market Awards Price Targets (in dollars per share) | $ / shares                 $ 172              
MSUs 2018 [Member] | Executive Officer [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)                 60,000              
MSUs 2018 [Member] | Non-Executive Employees [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)                 60,000              
2013 MSU's [Member]                                
Share Price (in dollars per share) | $ / shares                   $ 31.73            
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Maximum Percentage Allowed                   500.00%            
Maximum Stock Compensation Costs | $   $ 38,200                            
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate                   38.70%            
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate                   1.60%            
Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Discount for Postvesting Restrictions                   0.00%            
Share-based Compensation Arrangement by Share-based Payment Award, Number of Price Targets                   5            
Total MSUs Earned (in shares)   1,800,000                            
2013 MSU's [Member] | Minimum [Member]                                
Market Awards Price Targets (in dollars per share) | $ / shares                   $ 40            
2013 MSU's [Member] | Maximum [Member]                                
Market Awards Price Targets (in dollars per share) | $ / shares                   $ 56            
2013 MSU's [Member] | Executive Officer [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)                   276,000            
2013 MSU's [Member] | Non-Executive Employees [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)                   84,000            
The2014 Plan [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)                               5,500,000
Amended and Restated 2014 Plan [Member]                                
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares) 10,500,000                              
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)                       4,600,000        
Employee Stock Purchase Plan [Member]                                
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)                       4.5        
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee (in shares)                       2,000        
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares per Employee Value (in shares)                       25,000        
Share-based Compensation Arrangement by Share-based Payment Award, Automatic Increase Shares (in shares)                       1,000,000        
Share-basedCompensation Arrangement by Share-based Payment Award, Other Than Options, Percent Increases in Period                       2.00%        
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)                           28,000    
Employee Stock Purchase Plan Shares Issued, Intrinsic Value | $                           $ 2,500    
Proceeds from Stock Plans | $                           $ 3,800    
The 2004 Employee Stock Purchase Plan [Member]                                
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total | $                       $ 400        
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)                       14,000 17,000      
Employee Stock Purchase Plan Shares Issued, Intrinsic Value | $                       $ 1,600 $ 2,400      
Proceeds from Stock Plans | $                       $ 5,900 $ 4,700