Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Cash flows from operating activities:
Net loss	$ (17,311)	$ (10,006)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	2,708	1,784
Amortization/accretion of marketable securities	(378)	(26)
Stock-based compensation	16,460	14,195
Other non-cash items, net	142	26
Changes in operating assets and liabilities:
Accounts receivable	(245)	5,567
Inventories	617	415
Prepaid expenses and other current assets	1,007	180
Deferred tax assets	21	(8)
Other assets	60	(81)
Accounts payable	3,254	(2,366)
Accrued liabilities	(454)	(9,640)
Income taxes payable	(311)	(551)
Deferred revenue	36	281
Lease Liabilities	(727)	0
Other long-term liabilities	453	294
Net cash provided by operating activities	5,332	64
Cash flows from investing activities:
Purchase of investments	(35,583)	(8,969)
Sales of investments	10,023	3,500
Maturities of investments	29,195	15,850
Purchase of property and equipment	(513)	(671)
Net cash provided by investing activities	3,122	9,710
Cash flows from financing activities:
Stock repurchase	0	(20,624)
Proceeds from exercise of stock options and employee stock purchase plan	2,938	1,669
Payment for intangible asset	(995)	(799)
Net cash provided by (used in) financing activities	1,943	(19,754)
Net increase (decrease) in cash, cash equivalents and restricted cash	10,397	(9,980)
Cash, cash equivalents and restricted cash at beginning of period	194,058	346,681
Cash, cash equivalents and restricted cash at end of period	204,455	336,701
Supplemental disclosure of cash flow information:
Cash paid for income taxes	797	908
Supplemental disclosure of noncash investing and financing activities:
Unpaid liabilities related to intangible and fixed assets additions	$ 372	$ 342