CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Operating Activities
Net loss	$ (1,036)	$ (41,974)
Adjustments to reconcile net loss to net cash provided (used) by operating activities:
Depreciation and amortization expense	6,925	4,035
Amortization of debt discount and issuance costs	859	2,457
Provision for expected credit losses	874	1,529
Provision for (recovery of) inventory obsolescence	211	(81)
Change in fair value of common stock warrants	962	16,258
Amortization of discount on short-term investments	(306)	(1,127)
Benefit for deferred income taxes	0	(2,126)
Stock-based compensation expense	27,924	32,286
Other	(106)	36
Changes in operating assets and liabilities:
Accounts receivable, net	1,046	(50)
Inventories	(2,965)	(13,181)
Prepaid and other current assets	411	(2,101)
Other long-term assets	(159)	6
Accounts payable and accrued expenses	11,957	(3,779)
Employee-related liabilities	2,318	(3,094)
Deferred revenue	5,288	2,668
Other current liabilities	1,170	2,428
Other long-term liabilities	2,207	678
Net cash provided (used) by operating activities	57,580	(5,132)
Investing Activities
Purchases of short-term investments	(385,580)	(166,984)
Proceeds from maturities of short-term investments	308,607	54,709
Proceeds from sales of short-term investments	20,788	35,027
Purchases of property and equipment	(5,339)	(16,552)
Acquisition of intangible assets and equity investments	(9,331)	(4,805)
Net cash used in investing activities	(70,855)	(98,605)
Financing Activities
Proceeds from issuance of convertible senior notes, net of $8,809 debt issuance costs	0	278,691
Payment for capped call transactions related to convertible senior notes	0	(34,069)
Proceeds from issuance of common stock under Company stock plans, net	16,758	28,645
Proceeds from exercise of common stock warrants	438	2,036
Net cash provided by financing activities	17,196	275,303
Effect of foreign exchange rate changes on cash	44	(262)
Net increase in cash and cash equivalents	3,965	171,304
Cash and cash equivalents at beginning of period	94,613	51,175
Cash and cash equivalents at end of period	98,578	222,479
Supplemental disclosures of cash flow information
Income taxes paid	197	131
Supplemental schedule of non-cash investing and financing activities
Right-of-use assets obtained in exchange for operating lease obligations	15,087	8,805
Property and equipment included in accounts payable	452	977
Intangible costs in other current and other long-term liabilities	$ 1,029	$ 2,348