Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2019

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Data (Unaudited)

Quarterly Financial Data (Unaudited)

	First Quarter		Second Quarter	Third Quarter	Fourth Quarter	Total
	(Dollars in millions)
2019
Operating revenue	$	2,055	2,051	2,039	2,012	8,157
Operating income	760		750	748	626	2,884
Net income	487		477	477	386	1,827

	First Quarter		Second Quarter	Third Quarter	Fourth Quarter	Total
	(Dollars in millions)
2018
Operating revenue	$	2,130	2,101	2,149	2,113	8,493
Operating income	632		626	717	685	2,660
Net income	380		427	453	405	1,665