Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating activities
Net loss	$ (162,816)	$ (136,725)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	2,455	954
Stock-based compensation expense	26,128	18,401
Non-cash interest expense	3,312	2,757
Changes in operating assets and liabilities:
Accounts receivable	9,287	134
Inventories	(16,200)	(179)
Other assets	(4,731)	(3,345)
Accounts payable	895	5,119
Accrued expenses	(4,834)	(1,847)
Deferred revenues	(230)	(22)
Other liabilities	(898)	172
Net cash used in operating activities	(147,632)	(114,581)
Investing activities
Purchase of property and equipment	(1,619)	(1,790)
Net cash used in investing activities	(1,619)	(1,790)
Financing activities
Proceeds from sale of common stock, net of issuance costs		(8)
Proceeds from exercise of stock options and Employee Stock Purchase Plan	4,497	3,323
Net cash provided by financing activities	4,497	3,315
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	651	45
Decrease in cash, cash equivalents, and restricted cash	(144,103)	(113,011)
Cash, cash equivalents, and restricted cash at beginning of period	645,954	787,866
Cash, cash equivalents, and restricted cash at end of period	501,851	674,855
Non-cash investing and financing activities
Stock option exercise proceeds receivable as of period end		103
Leasehold improvement assets funded by lessor		585
Purchase of property and equipment - cash not paid as of period end	56	301
Supplemental disclosure of cash flow information
Cash paid for interest	12,274	3,019
Milestone obligation not paid as of period end		24,790
Income taxes paid	$ 80	$ 176