v3.26.1
Marketable Securities - Amortized Cost, Gross Unrealized Gains (Losses) and Fair Value of Available-For-Sale Securities (Detail) - USD ($)
$ in Thousands
Jan. 31, 2026
Jan. 31, 2025
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost $ 786,644 $ 728,147
Unrealized Gains 2,486 3,049
Unrealized (Losses) (548) (1,039)
Fair Value 788,582 730,157
Long-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 460,520 408,292
Unrealized Gains 1,851 2,821
Unrealized (Losses) (513) (905)
Fair Value 461,858 410,208
Short-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 326,124 319,855
Unrealized Gains 635 228
Unrealized (Losses) (35) (134)
Fair Value 326,724 319,949
Corporate Bonds | Long-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 330,319 233,418
Unrealized Gains 921 298
Unrealized (Losses) (436) (500)
Fair Value 330,804 233,216
Corporate Bonds | Short-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 232,594 186,732
Unrealized Gains 403 103
Unrealized (Losses) (28) (114)
Fair Value 232,969 186,721
US Treasury Securities | Long-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 80,872 92,852
Unrealized Gains 520 226
Unrealized (Losses) (20) (90)
Fair Value 81,372 92,988
US Treasury Securities | Short-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 38,288 5,415
Unrealized Gains 174 0
Unrealized (Losses) (2) (5)
Fair Value 38,460 5,410
Federal Government Agencies | Long-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 23,723 50,579
Unrealized Gains 10 16
Unrealized (Losses) (55) (292)
Fair Value 23,678 50,303
Federal Government Agencies | Short-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 17,454 53,663
Unrealized Gains 32 55
Unrealized (Losses) (2) (7)
Fair Value 17,484 53,711
Municipal And Pre-Refunded Municipal Bonds | Long-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 3,393 14,770
Unrealized Gains 17 35
Unrealized (Losses) (1) (8)
Fair Value 3,409 14,797
Municipal And Pre-Refunded Municipal Bonds | Short-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 27,964 53,772
Unrealized Gains 26 70
Unrealized (Losses) (3) (8)
Fair Value 27,987 53,834
Mutual Funds, Held in Rabbi Trust | Long-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 22,213 15,673
Unrealized Gains 383 2,246
Unrealized (Losses) (1) (15)
Fair Value 22,595 17,904
Commercial Paper | Short-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 8,824 9,774
Unrealized Gains 0 0
Unrealized (Losses) 0 0
Fair Value 8,824 9,774
Certificates of Deposit | Long-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost   1,000
Unrealized Gains   0
Unrealized (Losses)   0
Fair Value   1,000
Certificates of Deposit | Short-term Investments    
Schedule of Available-for-sale Securities [Line Items]    
Amortized Cost 1,000 10,499
Unrealized Gains 0 0
Unrealized (Losses) 0 0
Fair Value $ 1,000 $ 10,499