Debt - Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Debt Disclosure [Abstract]
Gross interest	$ 35,221	$ 33,341	$ 69,833	$ 65,078
Capitalized interest	(2,650)	(1,363)	(5,347)	(3,799)
Interest expense	$ 32,571	$ 31,978	$ 64,486	$ 61,279