Early Plant Retirements Early Plant Retirements (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
		Sep. 30, 2017	Sep. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Early Plant Retirements [Line Items]
Total Assets				$ 45,073	$ 42,716
Asset Retirement Obligations				1,059	1,024
Power [Member]
Early Plant Retirements [Line Items]
Total Assets				12,681	12,418
Asset Retirement Obligations				841	$ 810
Power [Member] | Energy Costs [Member]
Early Plant Retirements [Line Items]
Coal Inventory Lower of Cost or Market Adjustments		$ 1	$ 10
Power [Member] | Operation and Maintenance Expense [Member]
Early Plant Retirements [Line Items]
Restructuring Charges		$ 8	12
Power [Member] | Depreciation And Amortization [Domain]
Early Plant Retirements [Line Items]
Accelerated Depreciation including Asset Retirement Costs			$ 964
Hope Creek [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory				83
Nuclear Production, net of Accumulated Depreciation				684
Nuclear Fuel In-Service, net of Accumulated Depreciation				155
Construction Work in Progress (including nuclear fuel)				144
Total Assets				1,066
Asset Retirement Obligations				313
Total Liabilities				313
Net Assets				$ 753
% Owned				100.00%
Nuclear Support Facilities [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory	[1]			$ 0
Nuclear Production, net of Accumulated Depreciation	[1]			199
Nuclear Fuel In-Service, net of Accumulated Depreciation	[1]			0
Construction Work in Progress (including nuclear fuel)	[1]			2
Total Assets	[1]			201
Asset Retirement Obligations	[1]			0
Total Liabilities	[1]			0
Net Assets	[1]			201
Salem [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory				72
Nuclear Production, net of Accumulated Depreciation				642
Nuclear Fuel In-Service, net of Accumulated Depreciation				72
Construction Work in Progress (including nuclear fuel)				156
Total Assets				942
Asset Retirement Obligations				258
Total Liabilities				258
Net Assets				$ 684
% Owned				57.00%
Peach Bottom [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory				$ 42
Nuclear Production, net of Accumulated Depreciation				775
Nuclear Fuel In-Service, net of Accumulated Depreciation				103
Construction Work in Progress (including nuclear fuel)				87
Total Assets				1,007
Asset Retirement Obligations				213
Total Liabilities				213
Net Assets				$ 794
% Owned				50.00%

[1] Includes Hope Creek’s and Salem’s shared support facilities and other nuclear development capital.