Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities
Net income (loss)	$ 470,868	$ (153,518)	$ (147,787)
Income from discontinued operations, net of tax	546,872	2,766	3,832
Loss from continuing operations	(76,004)	(156,284)	(151,619)
Adjustments to reconcile net loss to net cash used in operating activities
Non-cash interest expense	3,678	6,004	8,217
Non-cash loss on extinguishment	5,202	14,566
Non-cash activity related to discontinued operations	17,282	13,224	11,215
Benefit from intra period tax allocation	(42,399)	(13,224)	(11,215)
Loss on disposal of property and equipment		493	4
Gain on sale of property and equipment	(439)	(40)
Impairment of in-process research and development intangible asset		2,800
Depreciation and amortization expense	5,221	4,895	3,250
Stock-based compensation expense	12,788	12,140	13,161
Loss on equity method investment	849
Gain on deconsolidation of Silver Creek Pharmaceuticals, Inc.	(10,848)
Changes in operating assets and liabilities:
Accounts receivable	175	(264)	1,654
Prepaid expenses and other assets	(8,476)	2,184	(32)
Accounts payable, accrued expenses and other	(9,278)	(9,837)	13,163
Deferred rent and tax incentives	(2,021)	408	2,374
Net cash used in continuing operations for operating activities	(104,270)	(122,935)	(109,828)
Net cash (used in) provided by discontinuing operations for operating activities	(41,665)	(47,306)	4,472
Net cash used in operating activities	(145,935)	(170,241)	(105,356)
Cash flows from investing activities
Purchase of marketable securities		(84,262)
Proceeds from sales and maturities of marketable securities		84,160	87,899
Purchase of property and equipment	(915)	(2,640)	(11,902)
Proceeds on sale of property and equipment	1,094
Proceeds from sale of discontinued operations	580,714
Net cash provided by (used in) continuing operations for investing activities	576,891	(2,742)	75,997
Net cash used in discontinuing operations for investing activities		(515)	(887)
Net cash provided by (used in) investing activities	576,891	(3,257)	75,110
Cash flows from financing activities
Proceeds from exercise of options and warrants to purchase common stock	6,917	6,224	10,087
Proceeds from at the market offering, net of issuance costs			38,560
Proceeds from issuance of senior secured notes due 2022, net of issuance costs			169,434
Proceeds from issuance of preferred stock by Silver Creek Pharmaceuticals, Inc.	3,994	3,361	2,083
Repayment of debt	(229,662)		(40,000)
Payment of dividend	(140,000)
Other financing activities, net	(288)	(169)
Net cash (used in) provided by financing activities	(359,039)	9,416	180,164
Net increase (decrease) in cash and cash equivalents	71,917	(164,082)	149,918
Cash and cash equivalents, beginning of period	21,524	185,606	35,688
Cash and cash equivalents, end of period	93,441	21,524	185,606
Non-cash investing and financing activities
Purchases of property and equipment in accounts payable, accrued expenses and other	14	130	816
Receivables related to stock option exercises in prepaid expenses and other current assets		232	14
Receivables related to the sale of property and equipment in prepaid expenses and other current assets		40
Principal amount of convertible notes due 2020 converted into shares of common stock		64,209
Supplemental disclosure of cash flows
Cash paid for income taxes	7,926
Cash paid for interest	30,966	$ 23,914	$ 10,087
Silver Creek Pharmaceuticals Inc [Member]
Adjustments to reconcile net loss to net cash used in operating activities
Loss on equity method investment	(800)
Gain on deconsolidation of Silver Creek Pharmaceuticals, Inc.	(10,848)
Cash flows from investing activities
Deconsolidation of Silver Creek Pharmaceuticals, Inc. cash	$ (4,002)