Benefit Plans (Tables)

9 Months Ended

Sep. 30, 2016

Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]

Components of Net Periodic Benefit Cost

	Qualified Plans						Nonqualified Plans
Three Months Ended September 30,	2016			2015			2016		2015
	(Dollars in millions)
Service cost	$	44		$	40		$	3	$	3
Interest cost	41			36			5		4
Estimated return on plan assets	(82		)	(82		)	—		—
Amortization and other	18			14			3		4
Net periodic benefit cost	$	21		$	8		$	11	$	11

	Qualified Plans						Nonqualified Plans
Nine Months Ended September 30,	2016			2015			2016		2015
	(Dollars in millions)
Service cost	$	130		$	125		$	9	$	9
Interest cost	122			104			14		12
Estimated return on plan assets	(244		)	(244		)	—		—
Amortization and other	51			38			9		11
Net periodic benefit cost	$	59		$	23		$	32	$	32