XML 60 R44.htm IDEA: XBRL DOCUMENT v3.21.1
Gross Unrealized Losses and Fair Value of Marketable Securities (Detail) - USD ($)
$ in Thousands
Jan. 31, 2021
Jan. 31, 2020
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value $ 192,533 $ 93,446
Less Than 12 Months, Unrealized Losses (330) (151)
Total, Fair Value 192,533 93,446
Total, Unrealized Losses (330) (151)
Municipal And Pre-Refunded Municipal Bonds    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 90,308 24,975
Less Than 12 Months, Unrealized Losses (99) (28)
Total, Fair Value 90,308 24,975
Total, Unrealized Losses (99) (28)
Corporate Bonds    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 91,432 60,067
Less Than 12 Months, Unrealized Losses (177) (66)
Total, Fair Value 91,432 60,067
Total, Unrealized Losses (177) (66)
Mutual Funds, Held in Rabbi Trust    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value 10,793 5,395
Less Than 12 Months, Unrealized Losses (54) (55)
Total, Fair Value 10,793 5,395
Total, Unrealized Losses $ (54) (55)
Federal Government Agencies    
Schedule of Available-for-sale Securities [Line Items]    
Less Than 12 Months, Fair Value   3,009
Less Than 12 Months, Unrealized Losses   (2)
Total, Fair Value   3,009
Total, Unrealized Losses   $ (2)