Segment Reporting - Company's Revenue by Geographic Region (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2015	Oct. 31, 2014
Revenue from External Customer [Line Items]
Total revenue	$ 93,200	$ 65,689	$ 248,406	$ 153,578
Hong Kong [Member]
Revenue from External Customer [Line Items]
Total revenue	84,053	61,134	228,371	138,527
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	1,015	420	2,331	1,638
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	2,190	1,328	4,756	5,196
North America other than United States [Member]
Revenue from External Customer [Line Items]
Total revenue	3,682	1,046	6,985	3,762
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 2,260	$ 1,761	$ 5,963	$ 4,455