Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Schedule of quarterly financial data (unaudited)

	Operating Revenue		Operating Income	Net Income (Loss)
	(Dollars in millions)
2018
First quarter (successor)	$	2,087	261	62
Second quarter (successor)	2,052		196	40
Third quarter (successor)	2,010		227	88
Fourth quarter (successor)	2,071		284	151
Total	$	8,220	968	341
2017
First quarter (predecessor)	$	2,048	337	95
Second quarter (predecessor)	2,062		353	154
Third quarter (predecessor)	2,059		349	157
Fourth quarter (predecessor)	701		112	19
Two months ended December 31 (successor)	1,407		158	(141	)
Total	$	8,277	1,309	284