v3.25.4
Employee Benefit Plans: Fair Value Measurements (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 274.3 $ 270.2 $ 308.6
Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 274.3 270.2  
Defined Benefit Plan, Fair Value of Plan Assets, Excluding Net Asset Value investments 254.5 247.7  
Defined Benefit Plan, Alternative Investments, Fair Value Of Plan Assets 19.8 22.5  
Fair Value, Measurements, Recurring | Healthcare Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 7.1 7.5  
Defined Benefit Plan, Fair Value of Plan Assets, Excluding Net Asset Value investments 7.1 7.5  
Defined Benefit Plan, Alternative Investments, Fair Value Of Plan Assets 0.0 0.0  
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Healthcare Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 7.1 7.5  
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 254.5 247.7  
Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Healthcare Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Healthcare Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 0.0 0.0  
Common Collective Trust Funds | Minimum      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period 15 days    
Common Collective Trust, Money Market | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 6.2    
Defined Benefit Plan, Fair Value of Plan Assets, Excluding Net Asset Value investments 6.2    
Defined Benefit Plan, Alternative Investments, Fair Value Of Plan Assets 0.0    
Common Collective Trust, Money Market | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0    
Common Collective Trust, Money Market | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 6.2    
Common Collective Trust, Money Market | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0    
Common Collective Trust, Cash And Cash Equivalents | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount   5.4  
Defined Benefit Plan, Fair Value of Plan Assets, Excluding Net Asset Value investments   5.4  
Defined Benefit Plan, Alternative Investments, Fair Value Of Plan Assets   0.0  
Common Collective Trust, Cash And Cash Equivalents | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount   0.0  
Common Collective Trust, Cash And Cash Equivalents | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount   5.4  
Common Collective Trust, Cash And Cash Equivalents | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount   0.0  
Common Collective Trust - Equity | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 51.9 51.5  
Defined Benefit Plan, Fair Value of Plan Assets, Excluding Net Asset Value investments 51.9 51.5  
Defined Benefit Plan, Alternative Investments, Fair Value Of Plan Assets 0.0 0.0  
Common Collective Trust - Equity | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Common Collective Trust - Equity | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 51.9 51.5  
Common Collective Trust - Equity | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Common Collective Trust - Fixed Income | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 196.4 190.8  
Defined Benefit Plan, Fair Value of Plan Assets, Excluding Net Asset Value investments 196.4 190.8  
Defined Benefit Plan, Alternative Investments, Fair Value Of Plan Assets 0.0 0.0  
Common Collective Trust - Fixed Income | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Common Collective Trust - Fixed Income | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 196.4 190.8  
Common Collective Trust - Fixed Income | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 0.0 0.0  
Common Collective Trust - Real Estate | Minimum      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period 105 days    
Common Collective Trust - Real Estate | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 14.8 14.9  
Defined Benefit Plan, Fair Value of Plan Assets, Excluding Net Asset Value investments 0.0 0.0  
Defined Benefit Plan, Alternative Investments, Fair Value Of Plan Assets 14.8 14.9  
Common Collective Trust - Real Estate | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Common Collective Trust - Real Estate | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Common Collective Trust - Real Estate | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 0.0 0.0  
Hedge Funds      
Defined Benefit Plan Disclosure [Line Items]      
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share, Investment Redemption, Notice Period 95 days    
Hedge Funds | Minimum      
Defined Benefit Plan Disclosure [Line Items]      
Percentage of partial redemptions subject to redemption gate 30.00%    
Hedge Funds | Maximum      
Defined Benefit Plan Disclosure [Line Items]      
Percentage of full redemptions subject to holdback of net asset value 10.00%    
Hedge Funds | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 5.0 7.6  
Defined Benefit Plan, Fair Value of Plan Assets, Excluding Net Asset Value investments 5.0 0.0  
Defined Benefit Plan, Alternative Investments, Fair Value Of Plan Assets 0.0 7.6  
Hedge Funds | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Hedge Funds | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Hedge Funds | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Pension Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Cash and Cash Equivalents | Fair Value, Measurements, Recurring | Healthcare Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 7.1 7.5  
Defined Benefit Plan, Fair Value of Plan Assets, Excluding Net Asset Value investments 7.1 7.5  
Defined Benefit Plan, Alternative Investments, Fair Value Of Plan Assets 0.0 0.0  
Cash and Cash Equivalents | Fair Value, Inputs, Level 1 | Fair Value, Measurements, Recurring | Healthcare Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 7.1 7.5  
Cash and Cash Equivalents | Fair Value, Inputs, Level 2 | Fair Value, Measurements, Recurring | Healthcare Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount 0.0 0.0  
Cash and Cash Equivalents | Fair Value, Inputs, Level 3 | Fair Value, Measurements, Recurring | Healthcare Plan      
Defined Benefit Plan Disclosure [Line Items]      
Defined Benefit Plan, Plan Assets, Amount $ 0.0 $ 0.0