Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Cash flows from operating activities:
Net loss	$ (10,818)	$ (15,463)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	2,883	2,872
Amortization (accretion) of premium (discount) on marketable debt securities, net	417	10
Stock-based compensation	18,842	16,036
Deferred income taxes	433	457
Other non-cash items, net	(190)	(38)
Changes in operating assets and liabilities:
Accounts receivable	(9,554)	(2,197)
Inventories	(7,039)	1,014
Prepaid expenses and other current assets	161	193
Other non-current assets	(65)	351
Accounts payable	(480)	5,679
Accrued and other current liabilities	1,969	(1,343)
Income taxes payable	(262)	58
Deferred revenue	(74)	101
Operating lease liabilities	(856)	(689)
Other long-term liabilities	86	598
Net cash provided by (used in) operating activities	(4,547)	7,639
Cash flows from investing activities:
Purchase of investments	(57,117)	(49,077)
Sales of investments	18,609	13,601
Maturities of investments	29,232	33,740
Purchase of tangible and intangible assets	(1,954)	(428)
Net cash used in investing activities	(11,230)	(2,164)
Cash flows from financing activities:
Stock repurchase	0	(1,000)
Proceeds from exercise of stock options and employee stock purchase plan	3,893	1,912
Payment for intangible assets	(1,881)	(1,205)
Net cash provided by (used in) financing activities	2,012	(293)
Net increase (decrease) in cash, cash equivalents and restricted cash	(13,765)	5,182
Cash, cash equivalents and restricted cash at beginning of period	241,284	231,412
Cash, cash equivalents and restricted cash at end of period	227,519	236,594
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1,013	370
Supplemental disclosure of noncash investing and financing activities:
Unpaid liabilities related to tangible and intangible assets additions	$ 304	$ 67