Leases - Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jul. 31, 2019	Apr. 30, 2019	Feb. 01, 2019
Leases [Abstract]
Operating lease right-of-use assets	$ 2,738	$ 3,014	$ 2,710
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	568
Right-of-use assets obtained in exchange for lease liabilities:
Operating leases	592
Total lease liabilities	2,738	3,014	$ 2,710
Operating lease liabilities - current	720	853
Operating lease liabilities - non-current	$ 2,018	$ 2,161