Debt - Interest Expense (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Disclosure [Abstract]
Gross interest cost	$ 133,137	$ 98,103	$ 33,077
Capitalized interest	(2,290)	(8,690)	(13,196)
Interest expense	$ 130,847	$ 89,413	$ 19,881