Income Taxes - Summary of Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Income Tax Disclosure [Abstract]
Income (loss) before income taxes	$ (8,429)	$ 15,437	$ (23,537)	$ 23,736
Provision for income taxes	$ 592	$ 3,713	$ 2,367	$ 6,145
Effective tax rate	(7.00%)	24.10%	(10.10%)	25.90%