CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2011
Cash flows from operating activities:
Net income	$ 18,188	$ 9,821	$ 13,929
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment	737	596	563
Loss on disposal of long-lived assets	4	23	4
Amortization of other intangible assets	270	540	1,040
Stock-based compensation	4,999	3,616	1,856
Net excess income tax benefits associated with stock-based compensation	7	(125)	0
Change in value of warrants	(149)	103	0
Changes in operating assets and liabilities:
Accounts receivable	(10,668)	(656)	260
Inventories	(2,132)	624	(5,731)
Prepaid expenses and other current assets	(1,134)	(511)	(27)
Deferred tax assets	(871)	(149)	486
Other assets	(443)	(113)	(227)
Accounts payable	193	(244)	1,575
Accrued liabilities	6,508	1,336	(322)
Income taxes payable	(244)	244	155
Deferred revenue	(4,751)	(2,419)	(536)
Net cash provided by operating activities	10,514	12,686	13,025
Cash flows from investing activities:
Restricted Cash	514	(274)	(243)
Short-term investment	0	0	5,000
Investment in a private company	0	102	(972)
Purchase of property and equipment	(1,528)	(682)	(896)
Purchase of intangible assets	0	(630)	(830)
Net cash provided by (used in) investing activities	(1,014)	(1,484)	2,059
Cash flows from financing activities:
Net proceeds from issuance of preference shares	0	11,627	0
Repurchase of ordinary shares, at cost	0	(7,228)	0
Net proceeds from exercise, repurchase of stock options and employee stock purchase plan	1,610	1,322	213
Proceeds from initial public offering, net of underwriting discounts and commissions and offering costs	30,440	0	0
Net excess income tax benefits associated with stock-based compensation	0	125	0
Net cash provided by financing activities	32,050	5,846	213
Net increase in cash and cash equivalents	41,550	17,048	15,297
Cash and cash equivalents at beginning of period	58,944	41,896	26,599
Cash and cash equivalents at end of period	100,494	58,944	41,896
Supplemental disclosure of cash flow information:
Cash paid for income taxes	3,402	854	657
Supplemental disclosure of noncash investing activities:
Increase in accrued liabilities related to non-monetary assets purchases	122	59	125
Supplemental disclosure of noncash financing activities:
Increase in accrued liabilities related to non-monetary financing activities	25	0	0
Conversion of convertible preference shares to ordinary shares	50,900	0	0
Conversion of convertible preference share warrants to ordinary share warrants	$ 110	$ 0	$ 0