Statement of Member's Equity Statement of Member's Equity - USD ($) $ in Thousands	Total	MEMBER'S CAPITAL	RETAINED EARINGS	ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)
Balance at beginning of period at Dec. 31, 2014		$ 1,073,892	$ 285,972	$ 90
Net income (loss)	$ 178,696		178,696
Cash distributions to parent	(168,000)		(168,000)
Reclassification of unrecognized gain into earnings	(62)			(62)
Balance at end of period at Dec. 31, 2015	1,370,588	1,073,892	296,668	28
Net income (loss)	180,455		180,455
Cash distributions to parent	(174,000)		(174,000)
Reclassification of unrecognized gain into earnings	(28)			(28)
Balance at end of period at Dec. 31, 2016	1,377,015	$ 1,073,892	303,123	0
Net income (loss)	(27,834)		(27,834)
Cash distributions to parent	(186,000)		(186,000)
Reclassification of unrecognized gain into earnings	0			0
Balance at end of period at Dec. 31, 2017	$ 1,163,181		$ 89,289	$ 0