Condensed Consolidated Statements of Cash Flows $ in Thousands	9 Months Ended
	Sep. 30, 2020 USD ($)		Sep. 30, 2019 USD ($)
Cash flows from operating activities:
Net loss	$ (364,811)		$ (479,372)
Adjustments to reconcile net loss to cash flows from operating activities:
Loss on contingent consideration	45,000	[1]
Gain from sale of Priority Review Voucher, net of commission	(108,069)
Acquired in-process research and development			173,240
Depreciation and amortization	19,623		17,853
Reduction in the carrying amounts of the right of use assets	8,749		4,488
Amortization of investment discount	(2,106)		(7,449)
Non-cash interest expense	18,532		15,887
Stock-based compensation	78,543		56,538
Other	75		892
Changes in operating assets and liabilities, net:
Net increase in accounts receivable	(30,948)		(18,988)
Net increase in inventory	(48,739)		(40,915)
Net increase in other assets	(114,127)		(94,710)
Net increase in deferred revenue	771,923
Net increase in accounts payable, accrued expenses and other liabilities	8,356		79,868
Net cash provided by (used in) operating activities	282,001		(292,668)
Cash flows from investing activities:
Purchase of property and equipment	(53,592)		(42,374)
Proceeds from sale of Priority Review Voucher, net of commission	108,069
Purchase of available-for-sale securities	(897,691)		(984,225)
Maturity and sale of available-for-sale securities	847,980		1,470,848
Acquisition of Myonexus Therapeutics, Inc., net of cash acquired			(172,556)
Other	(2,596)		(2,048)
Net cash provided by investing activities	2,170		269,645
Cash flows from financing activities:
Proceeds from issuance of common stock to Roche, net of offering costs			365,353
Proceeds from exercise of stock options and purchase of stock under the Employee Stock Purchase Program	48,131		24,572
Taxes paid related to net share settlement of equity awards	(4,798)		(4,337)
Net cash provided by financing activities	355,386		385,588
Increase in cash, cash equivalents and restricted cash	639,557		362,565
Cash, cash equivalents and restricted cash:
Beginning of period	843,645		370,829
End of period	1,483,202		733,394
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	1,474,637		724,829
Restricted cash in other assets	$ 8,565		$ 8,565
Restricted Cash, Noncurrent, Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent		us-gaap:OtherAssetsNoncurrent
Total cash, cash equivalents and restricted cash	$ 1,483,202		$ 733,394
Supplemental disclosure of cash flow information:
Cash paid during the period for interest	20,462		4,275
Supplemental schedule of non-cash investing activities and financing activities:
Intangible assets and property and equipment included in accrued expenses	8,292		$ 2,327
Lease liabilities arising from obtaining right of use assets	37,647
Roche
Cash flows from financing activities:
Proceeds from issuance of common stock to Roche, net of offering costs	$ 312,053

[1] The loss on contingent consideration is related to the fair value adjustment of the regulatory-related contingent payments that are accounted for as derivatives. Please see Note 5. Fair Value Measurements for further details.