Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016
Cash flows from operating activities:
Net income	$ 5,867	$ 10,415
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation of property and equipment	855	819
Amortization of intangible assets	1,147	23
Amortization/accretion of marketable securities	101	125
Stock-based compensation	27,407	22,767
Other non-cash items, net	43	67
Changes in operating assets and liabilities:
Accounts receivable	245	5,820
Inventories	2,419	(2,731)
Prepaid expenses and other current assets	1,618	2
Deferred tax assets	(525)	1,054
Other assets	(5)	119
Accounts payable	3,511	5,548
Accrued liabilities	(9,293)	(543)
Income taxes payable	1,446	(787)
Deferred tax liabilities	0	(58)
Deferred revenue	(1,222)	(4,613)
Other long-term liabilities	39	26
Net cash provided by operating activities	33,653	38,053
Cash flows from investing activities:
Purchase of investments	(28,049)	(50,214)
Sales of investments	4,500	19,827
Maturities of investments	14,840	19,560
Purchase of property and equipment	(1,853)	(997)
Net cash used in investing activities	(10,562)	(11,824)
Cash flows from financing activities:
Stock repurchase	(38,720)	(20,183)
Proceeds from exercise of stock options and employee stock purchase plan	3,396	2,405
Payment for software license liabilities	(901)	0
Net cash used in financing activities	(36,225)	(17,778)
Net increase (decrease) in cash and cash equivalents	(13,134)	8,451
Cash and cash equivalents at beginning of period	322,872	268,056
Cash and cash equivalents at end of period	309,738	276,507
Supplemental disclosure of cash flow information:
Cash paid for income taxes	567	637
Supplemental disclosure of noncash investing and financing activities:
Increase in liabilities related to intangible and fixed asset purchases	$ 9,193	$ 86