Commitments and Contingencies - Schedule of Future Minimum Lease Payments under Noncancelable Operating Leases (Details) $ in Thousands	Jan. 31, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
Minimum operating lease payment due in one year	$ 7,145
Minimum operating lease payment due in two years	7,175
Minimum operating lease payment due in three years	7,204
Minimum operating lease payment due in four years	7,233
Minimum operating lease payment due in five years	3,984
Committed gross lease payments	32,741
Less proceeds from sublease rental	(3,012)
Net operating lease obligation	$ 29,729