Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS USED IN OPERATING ACTIVITIES:
Net loss	$ (180,239)	$ (183,220)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,005	1,385
Amortization of discount on marketable securities, net	(199)	(100)
Amortization of debt discount and debt issuance costs	10,174	1,568
Stock-based compensation	22,270	28,785
Changes in operating assets and liabilities:
Inventory	(1,180)	(3,074)
Accounts receivable, net	(8,467)	(11,682)
Other current assets	(4,922)	(5,493)
Increase (Decrease) in Other Current Assets	(998)	0
Other long-term assets	210	(7)
Accounts payable	2,379	(2,414)
Accrued expenses and other current liabilities	(7,455)	7,327
Other non-current liabilities	(71)	(166)
Net cash used in operating activities	(164,497)	(167,091)
CASH FLOWS PROVIDED BY INVESTING ACTIVITIES:
Purchases of property and equipment	(70)	(2,950)
Payments for capitalized milestones	0	(8,712)
Purchases of marketable securities	(499)	(117,441)
Sales and maturities of marketable securities	97,501	170,208
Net cash provided by investing activities	96,932	41,105
CASH FLOWS PROVIDED BY FINANCING ACTIVITIES:
Proceeds from exercise of stock options and warrant exercises	8,953	16,167
Proceeds from issuance of convertible debt	0	305,000
Payment of debt issuance costs	0	(9,360)
Proceeds from issuance of shares under employee stock purchase plan	2,565	2,550
Net cash provided by financing activities	11,518	314,357
NET DECREASE IN CASH, CASH EQUIVALENTS, AND RESTRICTED CASH	(56,047)	188,371
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT BEGINNING OF YEAR	118,619	258,614
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH AT END OF PERIOD	62,572	446,985
SUPPLEMENTAL DISCLOSURES:
Cash paid for income taxes	22	26
Property and equipment purchases in accrued expenses at period end	$ 298	$ 487