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Marketable Securities - Gross Unrealized Losses and Fair Value of Marketable Securities (Detail) - USD ($)
$ in Thousands
Jan. 31, 2024
Jan. 31, 2023
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value $ 239,343 $ 61,489
Less Than 12 Months, Unrealized Losses (559) (1,571)
12 Months or Greater, Fair Value 75,293 182,208
12 Months or Greater, Unrealized Losses (1,504) (5,974)
Total, Fair Value 314,636 243,697
Total, Unrealized Losses (2,063) (7,545)
Municipal And Pre-Refunded Municipal Bonds    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 24,070 2,849
Less Than 12 Months, Unrealized Losses (48) (90)
12 Months or Greater, Fair Value 21,613 64,079
12 Months or Greater, Unrealized Losses (401) (1,752)
Total, Fair Value 45,683 66,928
Total, Unrealized Losses (449) (1,842)
Corporate Bonds    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 104,563 23,569
Less Than 12 Months, Unrealized Losses (168) (51)
12 Months or Greater, Fair Value 53,680 116,136
12 Months or Greater, Unrealized Losses (1,103) (4,215)
Total, Fair Value 158,243 139,705
Total, Unrealized Losses (1,271) (4,266)
US Treasury Securities    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 35,135 14,221
Less Than 12 Months, Unrealized Losses (62) (3)
12 Months or Greater, Fair Value 0 1,993
12 Months or Greater, Unrealized Losses 0 (7)
Total, Fair Value 35,135 16,214
Total, Unrealized Losses (62) (10)
Mutual Funds, Held in Rabbi Trust    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 1,059 11,333
Less Than 12 Months, Unrealized Losses (93) (1,424)
12 Months or Greater, Fair Value 0 0
12 Months or Greater, Unrealized Losses 0 0
Total, Fair Value 1,059 11,333
Total, Unrealized Losses (93) (1,424)
Federal Government Agencies    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 74,516 9,517
Less Than 12 Months, Unrealized Losses (188) (3)
12 Months or Greater, Fair Value 0 0
12 Months or Greater, Unrealized Losses 0 0
Total, Fair Value 74,516 9,517
Total, Unrealized Losses $ (188) $ (3)