Income Taxes - Additional Information (Details) - USD ($)	1 Months Ended	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Income Tax Disclosure [Abstract]
Valuation allowance increase (decrease)		$ (2,600,000)	$ 37,200,000
Unrecognized tax benefits	$ 6,068,000	6,068,000	3,598,000	$ 2,511,000
Interest and penalties related to uncertain tax positions		0	$ 0
Corporate tax rate, percentage	21.00%
Decrease in deferred tax assets		$ 59,200,000