Segment Information - Generation Total Revenues Net of Purchased Power and Fuel Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	$ 2,264	$ 2,204	$ 2,655
Generation Midwest [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	2,717	2,902	2,962
Generation New York [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	1,161	997	1,094
Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	(825)	426	308
Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	891	665	620
Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	6,208	7,194	7,639
Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	1,278	824	429
Unrealized Gain (Loss) on Securities	633	110	(4)
Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Revenue Net of Purchase Power And Fuel	7,486	8,018	8,068
Operating Segments [Member] | Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
RNF from external customers	2,247	2,174	2,637
Operating Segments [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
RNF from external customers	2,717	2,902	2,994
Operating Segments [Member] | Generation New York [Member]
Segment Reporting Information [Line Items]
RNF from external customers	1,151	983	1,081
Operating Segments [Member] | Generation ERCOT [Member]
Segment Reporting Information [Line Items]
RNF from external customers	(668)	407	338
Operating Segments [Member] | Generation Other Regions [Member]
Segment Reporting Information [Line Items]
RNF from external customers	984	759	694
Operating Segments [Member] | Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
RNF from external customers	6,431	7,225	7,744
Operating Segments [Member] | Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
RNF from external customers	1,055	793	324
Unrealized Gain (Loss) on Securities	565	295	(215)
Nuclear Fuel Amortization	148	60	13
Operating Segments [Member] | Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
RNF from external customers	7,486	8,018	8,068
Intersegment Eliminations [Member] | Generation Mid Atlantic [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	17	30	18
Intersegment Eliminations [Member] | Generation Midwest [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	0	0	(32)
Intersegment Eliminations [Member] | Generation New York [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	10	14	13
Intersegment Eliminations [Member] | Generation ERCOT [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	(157)	19	(30)
Intersegment Eliminations [Member] | Generation Other Regions [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	(93)	(94)	(74)
Intersegment Eliminations [Member] | Generation Reportable Segments Total [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	(223)	(31)	(105)
Intersegment Eliminations [Member] | Generation All Other Segments [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	223	31	105
Intersegment Eliminations [Member] | Generation Total Consolidated Group [Member]
Segment Reporting Information [Line Items]
Intersegment Revenue Net Of Purchase Power And Fuel	$ 0	$ 0	$ 0