CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Operating activities
Net loss	$ (191,579)	$ (206,850)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	26,274	27,769
Depreciation and amortization	4,128	3,632
Amortization of premiums and discounts on available-for-sale securities	(174)	(884)
Amortization of debt issuance costs	1,423	1,324
Write-off of debt issuance costs related to convertible senior notes transactions	4,344
Loss on convertible senior notes conversion	7,791
Loss on extinguishment of debt	3,277
Legal settlement loss		21,000
Changes in operating assets and liabilities:
Accounts receivable	2,359	(2,491)
Inventory	4,357	(35,351)
Prepaid and accrued research and development expenses	(5,328)	5,041
Other operating assets and liabilities	5,895	(5,587)
Accounts payable	(7,804)	(1,393)
Other accrued expenses	2,686	(2,698)
Net cash used in operating activities	(142,351)	(196,488)
Investing activities
Purchases of property and equipment	(75)	(1,484)
Purchases of available-for-sale securities	(9,962)	(205,779)
Sales of available-for-sale securities	144,644	296,845
Acquired in-process research and development - milestone payment	(8,000)	(15,750)
Net cash provided by investing activities	126,607	73,832
Financing activities
Proceeds from the sale of common stock, net of issuance costs	246,727
Payment of convertible senior notes	(164,443)
Proceeds from borrowings under financing agreement	33,322	6,862
Proceeds from the exercise of stock options and employee stock purchases	868	2,482
Payments on finance leases	(720)	(505)
Payments on other long-term liabilities	(103)
Net cash provided by financing activities	115,651	9,344
Effect of exchange rate changes on cash and cash equivalents	(304)	43
Increase (decrease) in cash and cash equivalents	99,603	(113,269)
Cash and cash equivalents at beginning of period	161,833	221,876
Cash and cash equivalents at end of period	261,436	108,607
Supplemental disclosure of cash flow information:
Cash paid for interest	6,006	5,469
Non-cash investing and financing activities:
Vesting of restricted stock units	$ 6,255	$ 4,283