Investments - Additional Information (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended								12 Months Ended
	May 31, 2016	Jan. 31, 2016	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 19, 2016
Schedule of Cost-method Investments [Line Items]
Payment for investment											$ 9,500
Charge resulting from decrease in fair market value											1,900		$ 835
Impairment charge											2,600
Research and development expense			$ 20,766	$ 20,080	$ 20,721	$ 20,312	$ 20,001	$ 16,304	$ 18,308	$ 18,243	81,879	$ 72,856	$ 64,284
Plain Vanilla Corp. | Convertible promissory notes
Schedule of Cost-method Investments [Line Items]
Investment amount		$ 7,500
Payment for investment	$ 2,500	5,000
Fair value of investment		$ 5,100												$ 3,200
Charge resulting from decrease in fair market value											1,900
Plain Vanilla Corp. | Call Option
Schedule of Cost-method Investments [Line Items]
Call option, term from closing of initial investment		15 months
Fair value of investment		$ 2,400
Impairment charge											2,400
Dairy Free, Inc. | Preferred stock
Schedule of Cost-method Investments [Line Items]
Investment amount		2,000
Dairy Free, Inc. | Preferred stock | Other long term assets
Schedule of Cost-method Investments [Line Items]
Investment amount			$ 2,000								$ 2,000
Dairy Free, Inc. | Advance recoupable development funding | Maximum
Schedule of Cost-method Investments [Line Items]
Recoupable and non-refundable development funding agreement amount		$ 1,000