Condensed Consolidated Statement of Member's Equity (Unaudited) - USD ($) $ in Thousands	Total	Member Units [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]
Balance at beginning of period at Dec. 31, 2018		$ 4,428,499	$ 2,099,567	$ 534
Cash contributions from parent		0
Net Income	$ 229,702		229,702
Cash distributions to parent	(176,000)		(176,000)
Equity interest in unrealized loss in interest rate hedge	(230)			(230)
Balance at end of period at Mar. 31, 2019	6,582,072	4,428,499	2,153,269	304
Balance at beginning of period at Dec. 31, 2019	6,605,783	4,428,499	2,177,284	0
Cash contributions from parent		0
Net Income	277,984		277,984
Cash distributions to parent	(270,000)		(270,000)
Equity interest in unrealized loss in interest rate hedge	0			0
Balance at end of period at Mar. 31, 2020	$ 6,613,767	$ 4,428,499	$ 2,185,268	$ 0