Benefit Plans (Tables)

6 Months Ended

Jun. 30, 2018

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost

The components of net periodic benefit cost for defined benefit pension plans are summarized in the following table:

		Three Months Ended June 30,						Six Months Ended June 30,
(Dollars in millions)	Location	2018			2017			2018			2017
Service cost	Personnel expense	$	60		$	53		$	120		$	105
Interest cost	Other expense	50			47			100			96
Estimated return on plan assets	Other expense	(112		)	(92		)	(224		)	(185		)
Amortization and other	Other expense	19			19			39			39
Net periodic benefit cost		$	17		$	27		$	35		$	55