Employee Pension and Other Postretirement Benefits (Tables)

6 Months Ended

Jun. 30, 2017

Compensation and Retirement Disclosure [Abstract]

Components of Net Periodic Benefit Cost

The following tables summarize the components of net periodic benefit cost for the three and six months ended June 30, 2017 and 2016.

	Pension Benefits						Other Postretirement Benefits						Superannuation, SERP and ESBP
	For the Three Months Ended   June 30,						For the Three Months Ended   June 30,						For the Three Months Ended   June 30,
(Dollars in millions)	2017			2016			2017			2016			2017		2016
Components of net periodic benefit cost:
Service cost	$	16		$	22		$	1		$	2		$	—	$	—
Interest cost	25			26			2			2			—		1
Expected return on plan assets	(63		)	(58		)	(4		)	(4		)	—		—
Amortization of prior service credit	(6		)	(5		)	(6		)	(2		)	—		—
Recognized net actuarial loss	21			19			1			3			1		—
Total net periodic benefit cost	$	(7	)	$	4		$	(6	)	$	1		$	1	$	1

	Pension Benefits						Other Postretirement Benefits						Superannuation, SERP and ESBP
	For the Six Months Ended June 30,						For the Six Months Ended June 30,						For the Six Months Ended June 30,
(Dollars in millions)	2017			2016			2017			2016			2017		2016
Components of net periodic benefit cost:
Service cost	$	35		$	45		$	3		$	4		$	—	$	1
Interest cost	50			52			4			5			1		1
Expected return on plan assets	(127		)	(118		)	(9		)	(9		)	—		—
Amortization of prior service credit	(13		)	(9		)	(11		)	(4		)	—		—
Recognized net actuarial loss	40			38			4			5			2		1
Total net periodic benefit cost	$	(15	)	$	8		$	(9	)	$	1		$	3	$	3