Retirement Benefits and Trusteed Assets (Details Textuals) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2013
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized (less than $1 million in 2012)	$ 24,000,000	$ 21,000,000	$ 19,000,000
Retiree Health Care Allowance will increase at lower of the rate of medical inflation or a set percentage	2.00%
Qualified Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions	145,000,000
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions	149,000,000	282,000,000
Defined Benefit Plan, Expected Return on Plan Assets	7.75%
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3	0	0
Discount rate	4.12%	4.95%	4.15%
Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions	0	239,000,000
Defined Benefit Plan, Expected Return on Plan Assets	8.00%
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers into Level 3	0	0
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3	0	0
Annual allocation to Retiree Reimbursement Account Per Participant, Retired on or before January 1, 2013	3,570	3,500
Annual allocation to Retiree Reimbursement Account Per Participant, Retired after January 1, 2013	3,315	3,250
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components	5,000,000
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation	89,000,000
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components	4,000,000
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation	77,000,000
Discount rate	4.10%	4.95%	4.15%	4.30%
Retirement Savings Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions to employee savings plan	4.00%
Maximum [Member] | Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	145,000,000
Maximum [Member] | Other Postretirement Benefit Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	175,000,000
Retiree Healthcare Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized (less than $1 million in 2012)	$ 2,000,000	$ 1,000,000