Convertible Senior Notes - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Disclosure [Abstract]
Amortization of debt discount	$ 19,436	$ 16,127
Amortization of debt issuance costs	1,844	1,531
Capitalization of interest expense	(2,755)	(2,195)
Total interest expense	$ 18,525	$ 15,463	$ 0