Convertible Senior Notes - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Disclosure [Abstract]
Amortization of debt discount and issuance costs	$ 22,040	$ 21,280
Capitalization of interest expense	(3,402)	(2,755)
Total interest expense	$ 18,638	$ 18,525	$ 15,463