Commitments and Contingencies (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017	Jan. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Operating leases, rent expense	$ 3,100,000	$ 2,100,000	$ 6,200,000	$ 4,200,000
Accrual for contingencies	$ 0		$ 0		$ 0