Convertible Senior Notes - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Amortization of debt discount	$ 36,013	$ 23,293	$ 0
Senior Notes Due 2019
Debt Instrument [Line Items]
Contractual interest expense	7,188	4,792
Amortization of debt issuance costs	3,974	2,461
Amortization of debt discount	32,039	20,832
Interest Expense, Debt	$ 43,201	$ 28,085