Convertible Senior Notes - Schedule of Convertible Notes (Details) - USD ($)	Mar. 31, 2016	Dec. 31, 2015	Feb. 28, 2014
Liability component:
Net carrying amount	$ 284,295,000	$ 281,627,000
Equity component	73,013,000	73,013,000
Convertible senior notes
Liability component:
Principal	345,000,000	345,000,000
Less: debt discount, net of amortization and reclassification of debt issuance costs	$ 60,705,000	$ 63,373,000
Net carrying amount			$ 345,000,000