Cash and Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 118,708	$ 166,734	$ 118,708	$ 166,734	$ 151,359
Cash	106,500		106,500		139,300
Readily determinable fair value of common stock investment	13,089		13,089		0
Loss on investment	(7,953)	0	(41,416)	0
Restricted Cash
Restricted cash	5,410	$ 5,048	5,410	$ 5,048	5,541
Restricted cash reserved for outstanding letters of credit associated with foreign taxes	5,000		5,000		4,100
Restricted cash reserved for other U.S. operating expenses	400		400
Restricted cash reserved for outstanding letters of credit associated with leased office space					1,000
Restricted cash in the form of a guaranteed investment certificate collateralizing an available credit facility					200
Restricted cash related to certain foreign tender requirements					300
Money market funds
Cash and Cash Equivalents [Line Items]
Money market funds with original maturities of less than three months	12,200		12,200		$ 12,100
Melinta
Cash and Cash Equivalents [Line Items]
Readily determinable fair value of common stock investment	$ 13,100		$ 13,100