Early Plant Retirements Early Plant Retirements (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Early Plant Retirements [Line Items]
Total Assets		$ 39,664	$ 40,070
Asset Retirement Obligations		738	726
Power [Member]
Early Plant Retirements [Line Items]
Total Assets		11,729	12,193
Asset Retirement Obligations		522	511
Power [Member] | Energy Costs [Member]
Early Plant Retirements [Line Items]
Coal Inventory Lower of Cost or Market Adjustments		7	62
Power [Member] | Operating Expense [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Obsolescence			53
Power [Member] | Depreciation And Amortization [Domain]
Early Plant Retirements [Line Items]
Accelerated Depreciation including Asset Retirement Costs		574	$ 571
Subsequent Event [Member] | Power [Member] | Depreciation And Amortization [Domain]
Early Plant Retirements [Line Items]
Accelerated Depreciation including Asset Retirement Costs	$ 389
Hope Creek [Member] | Nuclear Plant [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory		82
Nuclear Production, net of Accumulated Depreciation		456
Nuclear Fuel In-Service, net of Accumulated Depreciation		152
Construction Work in Progress (including nuclear fuel)		156
Total Assets		846
Asset Retirement Obligations		144
Total Liabilities		144
Net Assets		$ 702
% Owned		100.00%
Salem [Member] | Nuclear Plant [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory		$ 86
Nuclear Production, net of Accumulated Depreciation		545
Nuclear Fuel In-Service, net of Accumulated Depreciation		77
Construction Work in Progress (including nuclear fuel)		137
Total Assets		845
Asset Retirement Obligations		157
Total Liabilities		157
Net Assets		$ 688
% Owned		57.00%
Nuclear Support Facilities [Member] | Nuclear Plant [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory		$ 0
Nuclear Production, net of Accumulated Depreciation		208
Nuclear Fuel In-Service, net of Accumulated Depreciation		0
Construction Work in Progress (including nuclear fuel)		12
Total Assets		220
Asset Retirement Obligations		0
Total Liabilities		0
Net Assets		$ 220
% Owned		0.00%
Peach Bottom [Member] | Nuclear Plant [Member]
Early Plant Retirements [Line Items]
Materials and Supplies Inventory		$ 39
Nuclear Production, net of Accumulated Depreciation		774
Nuclear Fuel In-Service, net of Accumulated Depreciation		142
Construction Work in Progress (including nuclear fuel)		26
Total Assets		981
Asset Retirement Obligations		159
Total Liabilities		159
Net Assets		$ 822
% Owned		50.00%