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Marketable Securities - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Schedule of Available-for-sale Securities [Line Items]
Sales and maturities of marketable securities			$ 237,879	$ 384,999
Amortization of discounts and premiums, net	$ 1,804	$ 201	4,540	818
Other (Loss) Income, Net
Schedule of Available-for-sale Securities [Line Items]
Net realized gain (loss)	$ 9	$ 1	$ 13	$ (419)

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Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

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Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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