Condensed Consolidated Statement of Equity - USD ($) $ in Thousands	Total	Members' Equity [Member]	Accumulated Earnings (Deficit) [Member]
Balance, beginning at Dec. 31, 2016	$ 2,739,245	$ 2,739,245	$ 0
Equity [Roll Forward]
Distributions to Member	(143,402)	(78,554)	(64,848)
Net income (loss)	64,848	0	64,848
Balance, ending at Jun. 30, 2017	2,660,691	2,660,691	0
Balance, beginning at Mar. 31, 2017	2,682,740	2,682,740	0
Equity [Roll Forward]
Distributions to Member	(53,831)	(22,049)	(31,782)
Net income (loss)	31,782	0	31,782
Balance, ending at Jun. 30, 2017	2,660,691	2,660,691	0
Balance, beginning at Dec. 31, 2017	2,576,471	2,576,471	0
Equity [Roll Forward]
Distributions to Member	(159,623)	(77,687)	(81,936)
Net income (loss)	81,936	0	81,936
Balance, ending at Jun. 30, 2018	2,498,784	2,498,784	0
Balance, beginning at Mar. 31, 2018	2,519,881	2,519,881	0
Equity [Roll Forward]
Distributions to Member	(62,315)	(21,097)	(41,218)
Net income (loss)	41,218	0	41,218
Balance, ending at Jun. 30, 2018	$ 2,498,784	$ 2,498,784	$ 0