Early Plant Retirements Early Plant Retirements (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Early Plant Retirements [Line Items]
Total Assets		$ 42,790		$ 42,716
Asset Retirement Obligations		1,037		1,024
Power [Member]
Early Plant Retirements [Line Items]
Total Assets		12,263		12,418
Asset Retirement Obligations		821		$ 810
Power [Member] | Energy Costs [Member]
Early Plant Retirements [Line Items]
Coal Inventory Lower of Cost or Market Adjustments		4	$ 7
Power [Member] | Depreciation And Amortization [Domain]
Early Plant Retirements [Line Items]
Accelerated Depreciation including Asset Retirement Costs			$ 574
Hope Creek [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory		84
Nuclear Production, net of Accumulated Depreciation		602
Nuclear Fuel In-Service, net of Accumulated Depreciation		88
Construction Work in Progress (including nuclear fuel)		296
Total Assets		1,070
Asset Retirement Obligations		305
Total Liabilities		305
Net Assets		$ 765
% 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]	207
Nuclear Fuel In-Service, net of Accumulated Depreciation	[1]	0
Construction Work in Progress (including nuclear fuel)	[1]	1
Total Assets	[1]	208
Asset Retirement Obligations	[1]	0
Total Liabilities	[1]	0
Net Assets	[1]	208
Salem [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory		83
Nuclear Production, net of Accumulated Depreciation		653
Nuclear Fuel In-Service, net of Accumulated Depreciation		107
Construction Work in Progress (including nuclear fuel)		97
Total Assets		940
Asset Retirement Obligations		252
Total Liabilities		252
Net Assets		$ 688
% Owned		57.00%
Peach Bottom [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory		$ 41
Nuclear Production, net of Accumulated Depreciation		797
Nuclear Fuel In-Service, net of Accumulated Depreciation		136
Construction Work in Progress (including nuclear fuel)		20
Total Assets		994
Asset Retirement Obligations		207
Total Liabilities		207
Net Assets		$ 787
% Owned		50.00%

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