Convertible Senior Notes - Schedule of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Debt Disclosure [Abstract]
Amortization of debt discount and issuance costs	$ 5,485	$ 5,297	$ 10,923	$ 10,548
Capitalization of interest expense	(846)	(619)	(1,631)	(1,294)
Total interest expense	$ 4,639	$ 4,678	$ 9,292	$ 9,254