Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities:
Net loss	$ (189,592)	$ (92,567)
Adjustments to reconcile net loss to net cash used by operating activities
Share-based compensation	68,406	51,872
Depreciation	16,571	12,206
Amortization of intangible assets	4,736	7
Amortization of right-of-use assets	5,114	4,833
Amortization of premiums, accretion of discounts, and (gains) losses on debt securities	(645)	(2,308)
(Gains) losses on equity securities	(11,604)	4,568
Changes in operating assets and liabilities
Accounts receivable, net	(54,073)	(35,983)
Inventories	(4,070)	(19,911)
Prepaid expenses and other assets	(13,623)	6,275
Lease liability	(5,900)	(2,955)
Deferred revenue	0	(16,598)
Other liabilities	29,337	(679)
Net cash used by operating activities	(155,343)	(91,240)
Investing activities:
Purchases of securities	(574,700)	(147,555)
Proceeds from maturities of securities	372,000	220,000
Proceeds from sales of securities	194,733	0
Purchases of property and equipment	(47,146)	(33,331)
Net cash provided (used) by investing activities	(55,113)	39,114
Financing activities:
Proceeds from exercise of stock options and employee stock purchase plan	53,271	38,052
Net cash provided by financing activities	53,271	38,052
Effect of exchange rate changes on cash and cash equivalents	(57)	0
Net decrease in cash and cash equivalents	(157,242)	(14,074)
Cash and cash equivalents at beginning of period	274,562	78,186
Cash and cash equivalents at end of period	$ 117,320	$ 64,112