Early Plant Retirements Early Plant Retirements (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Total Assets		$ 42,716	$ 40,070	$ 37,535
Asset Retirement Obligations, Noncurrent		1,024	726
Power [Member]
Restructuring Cost and Reserve [Line Items]
Total Assets		12,418	12,193
Asset Retirement Obligations, Noncurrent		810	511
Power [Member] | Energy Costs [Member]
Restructuring Cost and Reserve [Line Items]
Coal Inventory Lower of Cost or Market Adjustments and Capacity Penalties		15	62
Power [Member] | Operation and Maintenance Expense [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		23	53
Power [Member] | Depreciation And Amortization [Domain]
Restructuring Cost and Reserve [Line Items]
Depreciation, including Asset Retirement Costs		964	$ 571
Nuclear Support Facilities [Member]
Restructuring Cost and Reserve [Line Items]
Public Utilities, Inventory	[1]	0
Nuclear Production, Net of Accumulated Depreciation	[1]	211
Nuclear Fuel, Net of Accumulated Depreciation	[1]	0
Public Utilities, Property, Plant and Equipment, Construction Work in Progress	[1]	1
Total Assets	[1]	212
Asset Retirement Obligations, Noncurrent	[1]	0
Liabilities	[1]	0
Net Assets	[1]	212
Peach Bottom [Member]
Restructuring Cost and Reserve [Line Items]
Public Utilities, Inventory		41
Nuclear Production, Net of Accumulated Depreciation		802
Nuclear Fuel, Net of Accumulated Depreciation		153
Public Utilities, Property, Plant and Equipment, Construction Work in Progress		25
Total Assets		1,021
Asset Retirement Obligations, Noncurrent		205
Liabilities		205
Net Assets		$ 816
Jointly Owned Utility Plant, Proportionate Ownership Share		50.00%
Peach Bottom [Member] | Power [Member]
Restructuring Cost and Reserve [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share		50.00%
Salem [Member]
Restructuring Cost and Reserve [Line Items]
Public Utilities, Inventory		$ 78
Nuclear Production, Net of Accumulated Depreciation		661
Nuclear Fuel, Net of Accumulated Depreciation		124
Public Utilities, Property, Plant and Equipment, Construction Work in Progress		90
Total Assets		953
Asset Retirement Obligations, Noncurrent		249
Liabilities		249
Net Assets		$ 704
Jointly Owned Utility Plant, Proportionate Ownership Share		57.00%
Salem [Member] | Power [Member]
Restructuring Cost and Reserve [Line Items]
Jointly Owned Utility Plant, Proportionate Ownership Share		57.00%
Hope Creek [Member]
Restructuring Cost and Reserve [Line Items]
Public Utilities, Inventory		$ 86
Nuclear Production, Net of Accumulated Depreciation		605
Nuclear Fuel, Net of Accumulated Depreciation		104
Public Utilities, Property, Plant and Equipment, Construction Work in Progress		245
Total Assets		1,040
Asset Retirement Obligations, Noncurrent		302
Liabilities		302
Net Assets		$ 738
Jointly Owned Utility Plant, Proportionate Ownership Share		100.00%

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