XML 38 R31.htm IDEA: XBRL DOCUMENT v3.25.2
Marketable Securities - Amortized Cost, Gross Unrealized Gains (Losses) and Fair Value of Available-For-Sale Securities (Detail) - USD ($)
$ in Thousands
Jul. 31, 2025
Jan. 31, 2025
Jul. 31, 2024
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost $ 656,628 $ 728,147 $ 560,836
Unrealized Gains 1,231 3,049 2,105
Unrealized (Losses) (859) (1,039) (1,112)
Fair Value 657,000 730,157 561,829
Short-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 290,849 319,855 353,116
Unrealized Gains 101 228 50
Unrealized (Losses) (286) (134) (806)
Fair Value 290,664 319,949 352,360
Long-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 365,779 408,292 207,720
Unrealized Gains 1,130 2,821 2,055
Unrealized (Losses) (573) (905) (306)
Fair Value 366,336 410,208 209,469
Corporate Bonds | Short-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 190,228 186,732 179,538
Unrealized Gains 59 103 26
Unrealized (Losses) (244) (114) (567)
Fair Value 190,043 186,721 178,997
Corporate Bonds | Long-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 216,635 233,418 79,873
Unrealized Gains 469 298 147
Unrealized (Losses) (336) (500) (87)
Fair Value 216,768 233,216 79,933
US Treasury Securities | Short-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 12,724 5,415 29,150
Unrealized Gains 19 0 0
Unrealized (Losses) (2) (5) (59)
Fair Value 12,741 5,410 29,091
US Treasury Securities | Long-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 84,454 92,852 49,951
Unrealized Gains 351 226 200
Unrealized (Losses) (26) (90) (45)
Fair Value 84,779 92,988 50,106
Federal Government Agencies | Short-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 30,609 53,663 73,850
Unrealized Gains 11 55 7
Unrealized (Losses) (7) (7) (115)
Fair Value 30,613 53,711 73,742
Federal Government Agencies | Long-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 39,635 50,579 35,635
Unrealized Gains 3 16 7
Unrealized (Losses) (172) (292) (105)
Fair Value 39,466 50,303 35,537
Municipal and Pre-Refunded Municipal Bonds | Short-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 48,111 53,772 47,174
Unrealized Gains 12 70 17
Unrealized (Losses) (33) (8) (65)
Fair Value 48,090 53,834 47,126
Municipal and Pre-Refunded Municipal Bonds | Long-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 4,940 14,770 25,250
Unrealized Gains 10 35 19
Unrealized (Losses) (3) (8) (69)
Fair Value 4,947 14,797 25,200
Certificates of Deposit | Short-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 1,249 10,499 20,499
Unrealized Gains 0 0 0
Unrealized (Losses) 0 0 0
Fair Value 1,249 10,499 20,499
Certificates of Deposit | Long-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost   1,000 1,000
Unrealized Gains   0 0
Unrealized (Losses)   0 0
Fair Value   1,000 1,000
Commercial Paper | Short-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 7,928 9,774 2,905
Unrealized Gains 0 0 0
Unrealized (Losses) 0 0 0
Fair Value 7,928 9,774 2,905
Mutual Funds, Held in Rabbi Trust | Long-term Investments      
Schedule of Available-for-sale Securities [Line Items]      
Amortized Cost 20,115 15,673 16,011
Unrealized Gains 297 2,246 1,682
Unrealized (Losses) (36) (15) 0
Fair Value $ 20,376 $ 17,904 $ 17,693