Segment Reporting - Company's Revenue by Geographic Region (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Revenue from External Customer [Line Items]
Total revenue	$ 121,066	$ 97,257	$ 94,739
Hong Kong [Member]
Revenue from External Customer [Line Items]
Total revenue	104,458	80,627	87,438
Asia Pacific [Member]
Revenue from External Customer [Line Items]
Total revenue	550	1,350	1,503
United States [Member]
Revenue from External Customer [Line Items]
Total revenue	7,990	9,825	2,213
North America [Member]
Revenue from External Customer [Line Items]
Total revenue	2,602	1,323	455
Europe [Member]
Revenue from External Customer [Line Items]
Total revenue	$ 5,466	$ 4,132	$ 3,130