Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2018

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)
2018
Operating revenue	$	2,130	2,101	2,149	2,113	8,493
Operating income	632		626	717	685	2,660
Income tax expense	130		81	111	172	494
Net income	380		427	453	405	1,665

	First Quarter		Second Quarter	Third Quarter	Fourth Quarter		Total
	(Dollars in millions)
2017
Operating revenue	$	2,162	2,133	2,141	2,114		8,550
Operating income	580		573	560	600		2,313
Income tax expense (benefit)	174		170	168	(378	)	134
Net income	278		268	265	846		1,657

In the fourth quarter of 2017, we recognized a tax benefit of $555 million due to the change in the federal corporate tax rate from 35% to 21%.