Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (144,522)	$ (125,866)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,908	5,577
Amortization (accretion) of premium (discount) on marketable securities	112	(61)
Non-cash interest expense	476	824
Amortization of operating lease right-of-use assets	1,301	580
Stock-based compensation	41,184	32,938
Changes in operating assets and liabilities:
Accounts receivable	(2,044)	(9,834)
Inventories	(6,841)	(24,926)
Prepaid expenses and other assets	(7,121)	181
Accounts payable	(9,730)	(4,918)
Accrued liabilities	7,683	(1,326)
Accrued compensation	(4,655)	(1,114)
Other liabilities		156
Operating lease liabilities	(2,328)	1,686
Net cash used in operating activities	(123,577)	(126,103)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(1,920)	(3,918)
Purchase of marketable securities		(57,936)
Maturities of marketable securities	47,670	261,738
Net cash provided by investing activities	45,750	199,884
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock in settlement of employee stock purchase plan and exercise of stock options	4,083	11,000
Payments of debt issuance costs	(49)	(130)
Tax paid related to net share settlement of equity awards	(1,962)	(2,172)
Net cash provided by financing activities	2,072	8,698
Effect of exchange rate changes on cash and cash equivalents	259
Net (decrease) increase in cash, cash equivalents and restricted cash	(75,496)	82,479
Cash, cash equivalents and restricted cash at beginning of period	497,202	304,632
Cash, cash equivalents and restricted cash at end of period	421,706	387,111
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	6,788	3,419
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING INFORMATION:
Leasehold improvements paid for by landlord		10,709
Accrued purchase of property and equipment	(36)	3,773
Accrued issuance costs	(26)	(85)
RECONCILIATION OF CASH, CASH EQUIVALENTS, AND RESTRICTED CASH TO THE CONDENSED CONSOLIDATED BALANCE SHEETS
Cash and cash equivalents	419,311	384,716
Restricted cash	2,395	2,395
Total cash and cash equivalents and restricted cash	$ 421,706	$ 387,111