Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2020
Cash flows from operating activities:
Net loss	$ (26,411)	$ (59,786)	$ (44,792)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	14,007	11,967	11,631
Amortization (accretion) of premium (discount) on marketable debt securities, net	1,034	721	(969)
Stock-based compensation	87,801	70,134	66,871
Deferred income taxes	(4,426)	(514)	187
Other non-cash items, net	(509)	65	(71)
Changes in operating assets and liabilities:
Accounts receivable	(18,600)	(6,487)	7,725
Inventories	(18,944)	(3,110)	(4,719)
Prepaid expenses and other current assets	228	(537)	1,057
Other non-current assets	832	1,141	(3,298)
Accounts payable	9,822	6,214	2,109
Accrued and other current liabilities	(1,954)	12,055	5,079
Income taxes payable	83	272	(302)
Deferred revenue	(131)	144	172
Operating lease liabilities	(3,608)	(2,416)	(2,851)
Other long-term liabilities	(429)	937	1,585
Net cash provided by operating activities	38,795	30,800	39,414
Cash flows from investing activities:
Acquisition, net of cash acquired	(307,038)	0	0
Purchases of investments	(118,726)	(219,677)	(225,913)
Sales of investments	208,132	70,087	96,363
Maturities of investments	107,760	123,208	122,795
Purchase of tangible and intangible assets	(9,679)	(4,942)	(1,821)
Net cash used in investing activities	(119,551)	(31,324)	(8,576)
Cash flows from financing activities:
Stock repurchase	0	(1,000)	0
Proceeds from exercise of stock options and employee stock purchase plan	15,292	16,417	11,960
Payment for intangible assets	(4,767)	(5,021)	(5,444)
Net cash provided by financing activities	10,525	10,396	6,516
Net increase (decrease) in cash, cash equivalents and restricted cash	(70,231)	9,872	37,354
Cash, cash equivalents and restricted cash at beginning of period	241,284	231,412	194,058
Cash, cash equivalents and restricted cash at end of period	171,053	241,284	231,412
Supplemental disclosure of cash flow information:
Cash paid for income taxes	1,869	1,531	1,811
Supplemental disclosure of noncash investing activities:
Unpaid liabilities related to tangible and intangible assets purchases	$ 1,569	$ 4,302	$ 12,284