Intangible Assets and Goodwill - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense	$ 4.3	$ 1.7	$ 1.0