Debt (Details) - USD ($)	1 Months Ended		12 Months Ended
	Mar. 31, 2021	Jul. 31, 2018	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2020
Debt Instrument [Line Items]
Interest payable			$ 0	$ 0
Line of Credit
Debt Instrument [Line Items]
Interest and prepayment fees	$ 1,200,000
Extinguishment of debt	$ 35,000,000
Line of Credit | Medium-term Notes | 2018 Loan
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 45,000,000
Amount borrowed			35,000,000
Issuance costs			1,100,000
Net proceeds from line of credit		$ 33,900,000
Debt maturity (in years)		5 years
Interest expense			$ 1,500,000	$ 3,300,000	$ 3,500,000
Line of Credit | Medium-term Notes | 2018 Loan | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		6.55%