Debt - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Debt Disclosure [Abstract]
Interest expense at coupon rate	$ 0	$ 1,930	$ 3,182	$ 3,411
Amortization of debt discounts and issuance costs	0	47	84	83
Total interest expense	$ 0	$ 1,977	$ 3,266	$ 3,494