Debt - Debt Issuance Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Disclosure [Abstract]
Non-cash interest expense	$ 14,700	$ 23,200	$ 26,100
Deferred financing costs	81,242	11,582	$ 13,020
Unamortized balances of deferred financing costs	$ 107,640	$ 44,648