Collaborative Arrangements and Licensing Agreements, Satellite Company Collaborations - Dynacure, SAS (Details) - USD ($)	3 Months Ended								12 Months Ended
	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
Collaborative Arrangement and Licensing Agreement [Abstract]
Revenue earned	$ 160,349,000	$ 110,927,000	$ 38,470,000	$ 36,874,000	$ 51,571,000	$ 49,121,000	$ 120,428,000	$ 62,583,000	$ 346,620,000	$ 283,703,000	$ 214,161,000
Dynacure, SAS [Member]
Collaborative Arrangement and Licensing Agreement [Abstract]
Ownership interest percentage	15.00%								15.00%
Maximum amount of payments receivable for license fee and substantive milestones	$ 210,000,000								$ 210,000,000
Maximum amount of payments receivable for development milestones	34,500,000								34,500,000
Maximum amount of payments receivable for regulatory milestones	111,000,000								111,000,000
Maximum amount of payments receivable for commercialization milestones	$ 60,000,000								60,000,000
Revenue earned									$ 0