Convertible Senior Notes - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Debt Disclosure [Abstract]
Amortization of debt discount and issuance costs	$ 5,534	$ 5,344	$ 16,457	$ 15,892
Capitalization of interest expense	(868)	(714)	(2,499)	(2,008)
Total interest expense	$ 4,666	$ 4,630	$ 13,958	$ 13,884