Retirement Plans (Tables)

12 Months Ended

Dec. 31, 2015

Retirement Plans [Abstract]

Projected Benefit Obligations, Fair Values of Plan Assets and Amounts Recognized in the Balance Sheet

($ in millions)	2015		2014
Change in projected benefit obligation (PBO)
PBO at beginning of year	$	2,210	$	1,669
PBO for plans of the Connecticut operations at contracted discount rate		-		342
Actuarial adjustment to PBO for plans of the Connecticut operations		5		5
Service cost		55		42
Interest cost		88		80
Actuarial (gain)/loss		(88)		182
Benefits paid		(128)		(110)
PBO at end of year	$	2,142	$	2,210
Change in plan assets
Fair value of plan assets at beginning of year	$	1,673	$	1,217
Fair value of plan assets for the Connecticut operations as of acquisition date		5		342
Actual return on plan assets		(40)		141
Employer contributions		62		83
Benefits paid		(128)		(110)
Fair value of plan assets at end of year	$	1,572	$	1,673
Funded status	$	(570)	$	(537)
Amounts recognized in the consolidated balance sheet
Pension and other postretirement benefits - current	$	(9)	$	(101)
Pension and other postretirement benefits - noncurrent	$	(561)	$	(436)
Accumulated other comprehensive loss	$	584	$	532

Net Periodic Benefit Cost

($ in millions)	2015		2014		2013
Components of total periodic pension benefit cost
Service cost	$	55	$	42	$	48
Interest cost on projected benefit obligation		88		80		76
Expected return on plan assets		(129)		(99)		(95)
Amortization of unrecognized loss		29		20		37
Net periodic pension benefit cost		43		43		66
Pension settlement costs		-		-		44
Total periodic pension benefit cost	$	43	$	43	$	110

Weighted Average Asset Allocations, By Asset Category

	2015		2014
Asset category:
Equity securities	47	%	45	%
Debt securities	46	%	47	%
Alternative investments	6	%	6	%
Cash and other	1	%	2	%
Total	100	%	100	%

Expected Benefit Payments Over The Next Ten Years

($ in millions)	Amount
2016	$	200
2017		160
2018		158
2019		157
2020		154
2021-2025		754
Total	$	1,583

Schedule of Assumptions Used

	2015		2014		2013
Discount rate - used at year end to value obligation	4.50	%	4.10	%	4.90	%
Discount rate - used to compute annual cost	4.10	%	4.90	%	4.00	%
Expected long-term rate of return on plan assets	7.75	%	7.75	%	8.00	%
Rate of increase in compensation levels	2.50	%	2.50	%	2.50	%

Schedule of Changes in Projected benefit Obligations for OPEB Table Text Block

($ in millions)	2015		2014
Change in benefit obligation
Benefit obligation at beginning of year	$	727	$	385
Benefit obligation for the Connecticut operations as of acquisition date		5		211
Service cost		19		11
Interest cost		30		22
Plan participants' contributions		5		5
Actuarial (gain)/loss		(115)		115
Benefits paid		(25)		(19)
Plan change		(20)		(3)
Benefit obligation at end of year	$	626	$	727
Change in plan assets
Fair value of plan assets at beginning of year	$	-	$	2
Plan participants' contributions		5		5
Employer contribution		20		12
Benefits paid		(25)		(19)
Fair value of plan assets at end of year	$	-	$	-
Funded status	$	(626)	$	(727)
Amounts recognized in the consolidated balance sheet
Pension and other postretirement benefits - current	$	(24)	$	(22)
Pension and other postretirement benefits - noncurrent	$	(602)	$	(705)
Accumulated other comprehensive (gain) loss	$	(20)	$	119

Schedule of Net Benefit Costs For OPEB Table Text Block

($ in millions)	2015		2014		2013
Components of net periodic postretirement benefit cost
Service cost	$	19	$	11	$	13
Interest cost on projected benefit obligation		30		22		17
Amortization of prior service cost /(credit)		(5)		(4)		(6)
Amortization of unrecognized loss		8		3		8
Net periodic postretirement benefit cost	$	52	$	32	$	32

Schedule of Assumptions Used for OPEB Table Text Block

	2015	2014	2013
Discount rate - used at year end to value obligation	4.50% - 4.70%	4.10% - 4.20%	4.90% - 5.20%
Discount rate - used to compute annual cost	4.10% - 4.20%	4.90% - 5.20%	4.00% - 4.20%

Schedule of Expected Benefit Payments for OPEB Table Text Block

($ in millions)	Gross Benefit		Medicare Part D Subsidy		Total
2016	$	25	$	-	$	25
2017		29		-		29
2018		33		-		33
2019		35		-		35
2020		38		-		38
2021-2025		211		1		210
Total	$	371	$	1	$	370

Net Periodic Benefit Cost Not Yet Recognized

($ in millions)	Pension Plan				OPEB
	2015		2014		2015		2014
Net actuarial loss	$	584	$	532	$	20	$	143
Prior service cost/(credit)		-		-		(40)		(24)
Total	$	584	$	532	$	(20)	$	119

Amounts Recognized as a Componenet of Accumulated Comprehensive Income

($ in millions)	Pension Plan				OPEB
	2015		2014		2015		2014
Accumulated other comprehensive loss at
beginning of year	$	532	$	412	$	119	$	5
Net actuarial gain (loss) recognized during year		(29)		(20)		(8)		(3)
Prior service (cost) credit recognized during year		-		-		5		4
Net actuarial loss (gain) occurring during year		81		140		(136)		113
Net amount recognized in comprehensive income
(loss) for the year		52		120		(139)		114
Accumulated other comprehensive (gain) loss at
end of year	$	584	$	532	$	(20)	$	119