Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Cash flows from operating activities:
Net income	$ 10,995	$ 7,828
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment	481	363
Loss on disposal of long-lived assets	2	2
Amortization of other intangible assets		270
Stock-based compensation	3,199	1,956
Net excess income tax benefits associated with stock-based compensation	(267)
Change in value of warrants		(14)
Changes in operating assets and liabilities:
Accounts receivable	(1,728)	(1,144)
Inventories	(995)	(1,603)
Prepaid expenses and other current assets	882	(741)
Deferred tax assets	(196)
Other assets	(14)	31
Accounts payable	4,388	1,567
Accrued liabilities	(2,610)	1,268
Income taxes payable	362	271
Deferred revenue	1,440	(3,994)
Net cash provided by operating activities	15,939	6,060
Cash flows from investing activities:
Restricted Cash		254
Net proceeds from disposal of fixed assets	13
Purchase of property and equipment	(1,293)	(302)
Net cash used in investing activities	(1,280)	(48)
Cash flows from financing activities:
Proceeds from exercise of stock options, warrants, and employee stock purchase plan withholding, net of repurchase of stock options	2,915	215
Payment for initial public offering cost	(25)
Net excess income tax benefits associated with stock-based compensation	267
Net cash provided by financing activities	3,157	215
Net increase in cash and cash equivalents	17,816	6,227
Cash and cash equivalents at beginning of period	100,494	58,944
Cash and cash equivalents at end of period	118,310	65,171
Supplemental disclosure of cash flow information:
Cash paid for income taxes	314	603
Supplemental disclosure of noncash investing activities:
Increase in accrued liabilities related to non-monetary assets purchases	$ 9	$ 2