Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Net loss	$ (17,782,000)	$ (30,153,000)
Loss from discontinued operations, net of tax	0	(947,000)
Loss from continuing operations	(17,782,000)	(29,206,000)
Adjustments to reconcile net loss to net cash used in operating activities
Non-cash interest expense		1,508,000
Depreciation and amortization expense	1,239,000	1,182,000
Premiums paid on marketable securities	(51,000)
Amortization and accretion on marketable securities	(141,000)
Stock-based compensation expense	764,000	796,000
Loss on equity method investment	746,000
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	801,000	(372,000)
Accounts payable, accrued expenses and other	(2,397,000)	8,054,000
Deferred rent	(518,000)	(86,000)
Net cash used in continuing operations for operating activities	(17,339,000)	(18,124,000)
Net cash provided by discontinuing operations for operating activities		7,968,000
Net cash used in operating activities	(17,339,000)	(10,156,000)
Cash flows from investing activities
Purchase of property and equipment	(16,000)	(290,000)
Purchases of marketable securities	(41,818,000)
Net cash used in investing activities	(41,834,000)	(290,000)
Cash flows from financing activities
Proceeds from exercise of options to purchase common stock		4,053,000
Net cash provided by financing activities		6,077,000
Net decrease in cash, cash equivalents and restricted cash	(59,173,000)	(4,369,000)
Cash, cash equivalents and restricted cash, beginning of period	94,217,000	22,300,000
Cash, cash equivalents and restricted cash, end of period	35,044,000	17,931,000
Non-cash investing and financing activities
Purchases of property and equipment in accounts payable, accrued expenses and other	$ 114,000	34,000
Receivables related to property and equipment sale in other current assets		76,000
Supplemental disclosure of cash flows
Cash paid for interest		1,368,000
Silver Creek Pharmaceuticals Inc [Member]
Cash flows from financing activities
Proceeds from issuance of Series C preferred stock by Silver Creek Pharmaceuticals, Inc., net of issuance costs		$ 2,024,000