Marketable Securities (Tables)

12 Months Ended

Jan. 31, 2022

Investments Debt And Equity Securities [Abstract]

Amortized Cost, Gross Unrealized Gains (Losses) and Fair Value of Available-For-Sale Securities

The amortized cost, gross unrealized gains (losses) and fair values of available-for-sale securities by major security type and class of security as of January 31, 2022 and 2021 are as follows:

	Amortized Cost		Unrealized Gains		Unrealized (Losses)			Fair Value
As of January 31, 2022
Short-term Investments:
Corporate bonds	$	85,062	$	1	$	(200	)	$	84,863
Municipal and pre-refunded municipal bonds		128,984		1		(273	)		128,712
US Treasury securities		14,999		—		(38	)		14,961
Commercial paper		10,884		—		—			10,884
		239,929		2		(511	)		239,420
Long-term Investments:
Corporate bonds	$	148,830	$	—	$	(2,478	)	$	146,352
Municipal and pre-refunded municipal bonds		60,533		1		(912	)		59,622
US Treasury securities		5,222		—		(46	)		5,176
Mutual funds, held in rabbi trust		12,419		—		(606	)		11,813
Federal government agencies		350		—		(5	)		345
Certificates of deposit		249		—		—			249
		227,603		1		(4,047	)		223,557
	$	467,532	$	3	$	(4,558	)	$	462,977

As of January 31, 2021
Short-term Investments:
Corporate bonds	$	38,695	$	1	$	(48	)	$	38,648
Municipal and pre-refunded municipal bonds		127,097		11		(53	)		127,055
Commercial paper		8,992		—		—			8,992
		174,784		12		(101	)		174,695
Long-term Investments:
Corporate bonds	$	59,890	$	3	$	(129	)	$	59,764
Municipal and pre-refunded municipal bonds		53,134		17		(46	)		53,105
Mutual funds, held in rabbi trust		10,827		20		(54	)		10,793
		123,851		40		(229	)		123,662
	$	298,635	$	52	$	(330	)	$	298,357

Gross Unrealized Losses and Fair Value of Marketable Securities

The following tables show the gross unrealized losses and fair value of the Company’s marketable securities with unrealized losses that are not deemed to have credit losses, aggregated by the length of time that individual securities have been in a continuous unrealized loss position, at January 31, 2022 and 2021, respectively.

	January 31, 2022
	Less Than 12 Months					12 Months or Greater					Total
Description of Securities	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses			Fair Value		Unrealized Losses
Corporate bonds	$	212,861	$	(2,661	)	$	14,110	$	(17	)	$	226,971	$	(2,678	)
Municipal and pre-refunded municipal bonds		162,081		(1,162	)		7,118		(23	)		169,199		(1,185	)
US Treasury securities		20,137		(84	)		—		—			20,137		(84	)
Mutual funds, held in rabbi trust		11,813		(606	)		—		—			11,813		(606	)
Federal government agencies		345		(5	)		—		—			345		(5	)
Total	$	407,237	$	(4,518	)	$	21,228	$	(40	)	$	428,465	$	(4,558	)

	January 31, 2021
	Less Than 12 Months					12 Months or Greater				Total
Description of Securities	Fair Value		Unrealized Losses			Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Corporate bonds	$	91,432	$	(177	)	$	—	$	—	$	91,432	$	(177	)
Municipal and pre-refunded municipal bonds		90,308		(99	)		—		—		90,308		(99	)
Mutual funds, held in rabbi trust		10,793		(54	)		—		—		10,793		(54	)
Total	$	192,533	$	(330	)	$	—	$	—	$	192,533	$	(330	)