Debt - Total Interest Expense Recognized Related to the Convertible Notes (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Debt Instrument [Line Items]
Total interest expense	$ 18,300	$ 18,443
Convertible Notes
Debt Instrument [Line Items]
Contractual interest expense	1,250	1,250
Amortization of debt issuance costs	274	258
Amortization of debt discount	1,929	1,815
Total interest expense	$ 3,453	$ 3,323