Summary of Significant Accounting Policies - Equity Method Investments - Additional Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Fair value of financial assets measured at fair value on a recurring basis	$ 376,093		$ 376,093		$ 291,762
Oragenics
Schedule of Equity Method Investments [Line Items]
Company's ownership percentage	29.50%		29.50%		30.70%
Equity securities
Schedule of Equity Method Investments [Line Items]
Fair value of financial assets measured at fair value on a recurring basis	$ 39,432		$ 39,432		$ 83,653
Equity securities | Oragenics
Schedule of Equity Method Investments [Line Items]
Fair value of financial assets measured at fair value on a recurring basis	6,171		6,171		$ 16,601
Unrealized appreciation (depreciation) in fair value of equity securities	$ (455)	$ 2,404	$ (11,597)	$ 6,283