Income Taxes - Components of Income before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Income Tax Disclosure [Abstract]
United States	$ 97,981	$ 82,331	$ 64,178
Foreign	11,654	(3,714)	3,008
Income before income taxes	$ 109,635	$ 78,617	$ 67,186