CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Operating activities
Net loss	$ (300,923)	$ (268,750)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	41,748	37,715
Depreciation and amortization	5,727	2,497
Amortization of premiums and discounts on available-for-sale securities	(1,269)	1,079
Amortization of debt issuance costs	2,070	1,536
Legal settlement loss	22,747
Acquired in-process research and development	9,440
Gain on extinguishment of debt	(18,480)
Loss on sale of property and equipment	783
Allowance for obsolete inventories	521
Lease liabilities	(716)
Changes in operating assets and liabilities:
Accounts receivable	(3,952)	(4,978)
Inventory	(23,473)	(25,540)
Prepaid and accrued research and development expenses	13,293	1,390
Deposit on inventory		(24,173)
Other operating assets	(5,263)	(7,507)
Accounts payable	2,384	4,765
Other accrued expenses	1,895	(1,304)
Net cash used in operating activities	(253,468)	(283,270)
Investing activities
Purchases of property and equipment	(2,887)	(7,763)
Proceeds from sale of property and equipment	275
Purchases of available-for-sale securities	(335,104)	(320,000)
Sales of available-for-sale securities	480,097	105,000
Acquired in-process research and development - milestone payment	(15,750)	(55,000)
Net cash provided by (used in) investing activities	126,631	(277,763)
Financing activities
Proceeds from the sale of common stock, net of issuance costs		93,890
Proceeds from the issuance of convertible senior notes, net of issuance costs	254,965	290,887
Proceeds from borrowings under financing agreement, net of issuance costs	19,044
Proceeds from the exercise of stock options and employee stock purchases	2,526	3,197
Extinguishment of convertible senior notes	(169,853)
Net cash provided by financing activities	106,682	387,974
Effect of exchange rate changes on cash and cash equivalents	(240)	(286)
Decrease in cash and cash equivalents	(20,395)	(173,345)
Cash and cash equivalents at beginning of period	221,876	464,198
Cash and cash equivalents at end of period	201,481	290,853
Supplemental disclosure of cash flow information:
Cash paid for interest	8,640	9,188
Non-cash investing and financing activities:
Vesting of restricted stock units	$ 4,735	$ 10,130