CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash Flows from Operating Activities:
Net Loss	$ (89,190)	$ (96,223)
Adjustments to Reconcile Net Loss to Net Cash Used in Operating Activities:
Depreciation and Amortization	3,392	2,135
Amortization of Intangible Assets	672	760
Amortization and Premium of Marketable Securities, Net	(171)	768
Loss on Sale or Disposal of Assets	6	74
In-Process Research and Development Impairment	13,000
Gain on Fair Value Remeasurement of Contingent Consideration	(200)
Income Tax Benefit	(5,200)
Stock-Based Compensation Expense	9,728	11,709
Non-Cash Expense		1,638
Changes in Operating Assets and Liabilities:
Accounts and Other Receivables	(1,229)	(609)
Prepaid and Other Current Assets	525	(325)
Other Assets	132
Accounts Payable and Accrued Expenses	(10,888)	(11,560)
Other Liabilities	(987)	(1,054)
Net Cash Used in Operating Activities	(80,410)	(92,687)
Cash Flows from Investing Activities:
Sales and Maturities of Marketable Securities	183,683	194,915
Purchases of Marketable Securities	(122,235)	(149,877)
Investment in Other		(1,801)
Acquisition of Property and Equipment	(1,598)	(2,113)
Net Cash Provided by Investing Activities	59,850	41,124
Cash Flows from Financing Activities:
Net Proceeds from Stock Issuances	32,642	10,666
Proceeds from Issuance of Stock from Employee Benefit Plans	192	532
Net Cash Provided by Financing Activities	32,834	11,198
Net Increase (Decrease) in Cash and Cash Equivalents	12,274	(40,365)
Cash and Cash Equivalents at Beginning of Period	42,461	72,108
Cash and Cash Equivalents at End of Period	54,735	31,743
Non-cash Investing Activities
Acquisition of Property and Equipment Included in Accounts Payable and Accrued Expenses	75	$ 65
Non-cash Supplemental Disclosure
Shares Issued to Former Kolltan Executive for Settlement of Severance	$ 302