Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018
Cash flows from operating activities:
Net loss	$ (27,502)	$ (16,883)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	5,439	3,565
Amortization/accretion of marketable debt securities	(696)	(106)
Stock-based compensation	32,660	29,325
Other non-cash items, net	87	200
Changes in operating assets and liabilities:
Accounts receivable	(1,728)	2,287
Inventories	876	(7,404)
Prepaid expenses and other current assets	1,541	1,318
Deferred tax assets	170	(118)
Other assets	(2,834)	(279)
Accounts payable	6,111	3,566
Accrued liabilities	(288)	(9,054)
Income taxes payable	90	(412)
Deferred revenue	24	318
Lease Liabilities	(1,454)	0
Other long-term liabilities	923	654
Net cash provided by operating activities	13,419	6,977
Cash flows from investing activities:
Purchase of investments	(91,143)	(39,639)
Sales of investments	32,573	15,120
Maturities of investments	71,395	31,750
Purchase of property and equipment	(954)	(1,977)
Net cash provided by investing activities	11,871	5,254
Cash flows from financing activities:
Stock repurchase	0	(65,614)
Proceeds from exercise of stock options and employee stock purchase plan	5,429	3,672
Payment for intangible asset	(2,075)	(1,672)
Net cash provided by (used in) financing activities	3,354	(63,614)
Net increase (decrease) in cash, cash equivalents and restricted cash	28,644	(51,383)
Cash, cash equivalents and restricted cash at beginning of period	194,058	346,681
Cash, cash equivalents and restricted cash at end of period	222,702	295,298
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1,283	1,009
Supplemental disclosure of noncash investing and financing activities:
Unpaid liabilities related to intangible and fixed assets additions	$ 347	$ 286