Benefit Plans (Tables)

3 Months Ended

Mar. 31, 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 March 31,
(Dollars in millions)	Location	2018			2017
Service cost	Personnel expense	$	60		$	52
Interest cost	Other expense	50			49
Estimated return on plan assets	Other expense	(112		)	(93		)
Amortization and other	Other expense	20			20
Net periodic benefit cost		$	18		$	28