Debt - Outstanding Convertible Note Balances (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Liability component:
Principal	$ 861,061
Net carrying amount	279,546	$ 179,363
Convertible Notes
Liability component:
Principal	361,061
Less: debt discount and issuance costs, net	81,515
Net carrying amount	279,546
Equity Component	85,266
Convertible Notes | 2022 Convertible Notes
Liability component:
Principal	320,000
Less: debt discount and issuance costs, net	78,203
Net carrying amount	241,797
Equity Component	72,576
Convertible Notes | 2019 Convertible Notes
Liability component:
Principal	41,061
Less: debt discount and issuance costs, net	3,312
Net carrying amount	37,749
Equity Component	$ 12,690