Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated Other Comprehensive Income (Loss), Net of Tax (Reclassifications out of AOCI) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Amount Reclassified from AOCI for Pension and OPEB Plans, After-Tax	$ (37)
Amount Reclassified from Accumulated Other Comprehensive Income, Pre-Tax	23
Amount Reclassified from Accumulated Other Comprehensive Income, Tax	(17)
Amount Reclassified from Accumulated Other Comprehensive Income, After-Tax	6
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Amount Reclassified from AOCI for Available for Sale Securities, Pre-Tax	75
Amount Reclassified from AOCI for Available for Sale Securities, Tax	(39)
Amount Reclassified from AOCI for Available for Sale Securities, After-Tax	36
Accumulated Defined Benefit Plans Adjustment [Member]
Amount Reclassified from AOCI for Pension and OPEB Plans, Pre-Tax	(64)
Amount Reclassified from AOCI for Pension and OPEB Plans, Tax	27
Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Amount Reclassified from AOCI for Cash Flow Hedges, Pre-Tax	12
Amount Reclassified from AOCI for Cash Flow Hedges, Tax	(5)
Amount Reclassified from AOCI for Cash Flow Hedges, After-Tax	7
Operating Revenues [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Amount Reclassified from AOCI for Cash Flow Hedges, Pre-Tax	13
Amount Reclassified from AOCI for Cash Flow Hedges, Tax	(5)
Amount Reclassified from AOCI for Cash Flow Hedges, After-Tax	8
Operation and Maintenance Expense [Member]
Amortization of Prior Service (Cost) Credit, After-Tax	7
Amortization of Actuarial Loss, After-Tax	(44)
Operation and Maintenance Expense [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Amortization of Prior Service (Cost) Credit, Pre-Tax	11
Amortization of Prior Service (Cost) Credit, Tax	4
Amortization of Actuartial Loss, Pre-Tax	(75)
Amortization of Actuarial Loss, Tax	31
Other Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Amount Reclassified from AOCI for Available for Sale Securities, Pre-Tax	116
Amount Reclassified from AOCI for Available for Sale Securities, Tax	(59)
Amount Reclassified from AOCI for Available for Sale Securities, After-Tax	57
Interest Expense [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Amount Reclassified from AOCI for Cash Flow Hedges, Pre-Tax	(1)
Amount Reclassified from AOCI for Cash Flow Hedges, Tax	0
Amount Reclassified from AOCI for Cash Flow Hedges, After-Tax	(1)
Other Deductions [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Amount Reclassified from AOCI for Available for Sale Securities, Pre-Tax	29
Amount Reclassified from AOCI for Available for Sale Securities, Tax	(14)
Amount Reclassified from AOCI for Available for Sale Securities, After-Tax	15
Other-Than-Temporary Impairments [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Amount Reclassified from AOCI for Available for Sale Securities, Pre-Tax	12
Amount Reclassified from AOCI for Available for Sale Securities, Tax	(6)
Amount Reclassified from AOCI for Available for Sale Securities, After-Tax	6
Power [Member]
Amortization of Actuarial Loss, After-Tax	(38)
Amount Reclassified from AOCI for Pension and OPEB Plans, After-Tax	(33)
Amount Reclassified from Accumulated Other Comprehensive Income, Pre-Tax	32
Amount Reclassified from Accumulated Other Comprehensive Income, Tax	(21)
Amount Reclassified from Accumulated Other Comprehensive Income, After-Tax	11
Power [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Amount Reclassified from AOCI for Available for Sale Securities, Pre-Tax	74
Amount Reclassified from AOCI for Available for Sale Securities, Tax	(38)
Amount Reclassified from AOCI for Available for Sale Securities, After-Tax	36
Amount Reclassified from Accumulated Other Comprehensive Income, After-Tax	36
Power [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Amount Reclassified from AOCI for Pension and OPEB Plans, Pre-Tax	(55)
Amount Reclassified from AOCI for Pension and OPEB Plans, Tax	22
Amount Reclassified from Accumulated Other Comprehensive Income, After-Tax	(33)
Power [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Amount Reclassified from AOCI for Cash Flow Hedges, Pre-Tax	13
Amount Reclassified from AOCI for Cash Flow Hedges, Tax	(5)
Amount Reclassified from AOCI for Cash Flow Hedges, After-Tax	8
Amount Reclassified from Accumulated Other Comprehensive Income, After-Tax	8
Power [Member] | Operating Revenues [Member] | Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member]
Amount Reclassified from AOCI for Cash Flow Hedges, Pre-Tax	13
Amount Reclassified from AOCI for Cash Flow Hedges, Tax	(5)
Amount Reclassified from AOCI for Cash Flow Hedges, After-Tax	8
Power [Member] | Operation and Maintenance Expense [Member]
Amortization of Prior Service (Cost) Credit, After-Tax	5
Power [Member] | Operation and Maintenance Expense [Member] | Accumulated Defined Benefit Plans Adjustment [Member]
Amortization of Prior Service (Cost) Credit, Pre-Tax	9
Amortization of Prior Service (Cost) Credit, Tax	4
Amortization of Actuartial Loss, Pre-Tax	(64)
Amortization of Actuarial Loss, Tax	26
Power [Member] | Other Income [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Amount Reclassified from AOCI for Available for Sale Securities, Pre-Tax	112
Amount Reclassified from AOCI for Available for Sale Securities, Tax	(57)
Amount Reclassified from AOCI for Available for Sale Securities, After-Tax	55
Power [Member] | Other Deductions [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Amount Reclassified from AOCI for Available for Sale Securities, Pre-Tax	26
Amount Reclassified from AOCI for Available for Sale Securities, Tax	(13)
Amount Reclassified from AOCI for Available for Sale Securities, After-Tax	13
Power [Member] | Other-Than-Temporary Impairments [Member] | Accumulated Net Unrealized Investment Gain (Loss) [Member]
Amount Reclassified from AOCI for Available for Sale Securities, Pre-Tax	12
Amount Reclassified from AOCI for Available for Sale Securities, Tax	(6)
Amount Reclassified from AOCI for Available for Sale Securities, After-Tax	$ 6