License Agreements (Narrative) (Details)					1 Months Ended							3 Months Ended								12 Months Ended				24 Months Ended
	Sep. 13, 2012 USD ($)	Nov. 18, 2011 USD ($) item	Jul. 22, 2011 USD ($)	Apr. 08, 2011 USD ($)	Jan. 31, 2017 USD ($)	Apr. 30, 2016 shares	Feb. 29, 2016 USD ($)	Nov. 30, 2015 USD ($)	Apr. 30, 2015 USD ($)	Dec. 31, 2014 shares	Jun. 30, 2008 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($)	Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($) item	Dec. 31, 2015 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2016 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue												$ 187,000	$ 1,036,000	$ 1,698,000	$ 2,336,000	$ 3,010,000	$ 4,345,000	$ 4,967,000	$ 6,192,000	$ 5,257,000	$ 18,514,000	$ 29,299,000
Accounts receivable, net												325,000				655,000				325,000	655,000			$ 655,000
Proceeds from issuance of redeemable convertible units																					5,500,000	10,833,000
Research and development												10,499,000	$ 11,775,000	$ 10,056,000	$ 8,447,000	$ 8,539,000	9,631,000	$ 8,587,000	9,083,000	40,777,000	35,840,000	33,558,000
Gain on settlement of payable																	$ 256,000		$ 3,875,000		4,131,000
Loss on equity method investment																				(7,599,000)	$ (13,625,000)	(2,776,000)
License Agreement, Symphony Evolution, Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Acquisition and worldwide development milestone payment																				14,100,000
Commercial milestone payment																				0
License Agreement, Symphony Evolution, Inc. [Member] | Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Acquisition and worldwide development milestone payment																				218,400,000
Commercial milestone payment																				175,000,000
License Agreement, Valeant Pharmaceuticals North America LLC, Syprine [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Gain on settlement of payable							$ 3,900,000
License Agreement, Princeton University [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
License maintenance fees																				60,000
Contingent milestone payments												$ 31,000,000								$ 31,000,000
Number of milestones met | item																				0	0
License agreement sales																				$ 0	$ 0
License Agreement, MeiraGTx Ltd. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Service revenue to license																				600,000	1,000,000	1,000,000
Shares received for settlement | shares						230,000
Settled receivables																				1,200,000
Cash payments for service revenue																				$ 300,000	200,000
Equity method investment, ownership percentage									48.00%			25.60%								25.60%
Equity method investment, cost									$ 0
Equity method investment, fair value									24,000,000			$ 0								$ 0
Equity method investment, gain based on the fair value									$ 24,000,000
Equity method investment, gross profit (loss)																				(7,600,000)	$ (13,600,000)	(2,800,000)
Loss on equity method investment																				$ (3,900,000)
License Agreement, MeiraGTx Ltd. [Member] | Class A [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Equity method investment, ownership percentage												38.70%								38.70%
License Agreement, Nano Terra, Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Ownership percentage																				1.00%	1.00%
Shares converted | shares										100
License Agreement, Nano Terra, Inc. [Member] | Class B Units [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Purchase of shares				$ 2,300,000
NT Life Sciences, LLC (“NT Life”) [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Equity method investment, gross profit (loss)																							$ (450,000)
Purchase of shares				$ 900,000
Ownership percentage				50.00%
Equity method investment, impairment																							$ 450,000
License Agreement, Dyax Corp. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
License agreement, upfront fee / payment	$ 500,000		$ 600,000
License maintenance fees			300,000
License agreement, obligation amortized over agreement term			300,000
License agreement, obligation amortized over one year			$ 300,000
License Agreement, Shire Plc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Research and development																				$ 1,500,000
License Agreement, Chiromics [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
License agreement, upfront fee / payment		$ 200,000
Number of chemical compounds | item		2
License agreement, fee for chemical compound		$ 200,000
License agreement, quarterly fee for chemical compounds		$ 200,000
Number of quarters, quarterly fee for chemical compounds | item		8
License Agreement, Zydus [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
One time purchase price of rights, title and interest to high dosages of ribavirin											$ 1,100,000
Estimated percentage of royalty based on net sales of products											20.00%
Royalty expense																				100,000	$ 1,200,000	2,700,000
License Agreement, Jinghua [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Sublicensing revenue																				$ 0	0	0
Proceeds from issuance of redeemable convertible units								$ 10,000,000
License agreement, term																				10 years
Revenue recognition, milestone method, revenue recognized					$ 2,000,000															$ 2,000,000	2,000,000
Estimated percentage of sublicensing revenue								10.00%
Number of patents licensed | item																				0
License Agreement, Jinghua [Member] | Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Contingent milestone payments								$ 40,000,000
Estimated percentage of sublicensing revenue																				30.00%
License Agreement, Jinghua [Member] | Minimum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Estimated percentage of sublicensing revenue																				10.00%
License Agreement, Camber Pharmaceuticals, Inc., Tetrabenazine [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue																				$ 1,000,000	600,000	0
License Agreement, Camber Pharmaceuticals, Inc., Valganciclovir [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
License agreement sales																								$ 0
Revenue																				200,000	900,000
License Agreement, Camber Pharmaceuticals, Inc., Abacavir, Entecavir, Lamivudine, Lamivudine (HBV) and Lamivudine and Zidovudine [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Revenue																				$ 0	$ 0	$ 0