v3.26.1
Fair Value of Financial Assets and Liabilities - Fair Value Measurement of Assets and Liabilities, Recurring (Details) - USD ($)
Mar. 31, 2026
Dec. 31, 2025
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents $ 332,000,000 $ 42,000,000
NDT fund investments 19,494,000,000 19,396,000,000
Rabbi trust investments 109,000,000 112,000,000
Investments in equities 60,000,000 87,000,000
Economic hedges 22,159,000,000 12,393,000,000
Effect of netting and allocation of collateral (18,251,000,000) (10,998,000,000)
Derivative assets subtotal 3,908,000,000 1,395,000,000
Economic hedges (21,262,000,000) (13,231,000,000)
Effect of netting and allocation of collateral 19,934,000,000 12,350,000,000
Derivative liabilities subtotal (1,328,000,000) (881,000,000)
Deferred compensation obligation (110,000,000) (124,000,000)
Total liabilities measured at fair value (1,438,000,000) (1,005,000,000)
Total net assets 22,465,000,000 20,027,000,000
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents 332,000,000 42,000,000
Derivative asset notational amounts 1,053,000,000 810,000,000
Cash equivalents    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 453,000,000 237,000,000
Equities    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 7,072,000,000 7,671,000,000
Fixed income    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 4,415,000,000 4,162,000,000
Private credit    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 133,000,000 132,000,000
Cash and Cash Equivalents | Constellation Energy Generation, LLC    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents 734,000,000 3,621,000,000
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents 734,000,000 3,621,000,000
Cash and Cash Equivalents | CEG Parent    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents 352,000,000 70,000,000
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents 352,000,000 70,000,000
Restricted cash | Constellation Energy Generation, LLC    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents 70,000,000 57,000,000
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents 70,000,000 57,000,000
Cash | CEG Parent    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents 15,000,000 0
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents 15,000,000 0
NDT fund investments subtotal    
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Net liabilities 231,000,000 166,000,000
Total assets measured at fair value    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Total assets 23,903,000,000 21,032,000,000
Level 1    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents 332,000,000 42,000,000
NDT fund investments 8,826,000,000 8,518,000,000
Rabbi trust investments 65,000,000 66,000,000
Investments in equities 60,000,000 87,000,000
Economic hedges 2,102,000,000 1,114,000,000
Effect of netting and allocation of collateral (1,940,000,000) (889,000,000)
Derivative assets subtotal 162,000,000 225,000,000
Total assets 9,445,000,000 8,938,000,000
Economic hedges (2,349,000,000) (1,148,000,000)
Effect of netting and allocation of collateral 2,222,000,000 1,065,000,000
Derivative liabilities subtotal (127,000,000) (83,000,000)
Deferred compensation obligation 0 0
Total liabilities measured at fair value (127,000,000) (83,000,000)
Total net assets 9,318,000,000 8,855,000,000
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents 332,000,000 42,000,000
Level 1 | Cash equivalents    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 290,000,000 72,000,000
Level 1 | Equities    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 6,000,000,000 6,245,000,000
Level 1 | Fixed income    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 2,536,000,000 2,201,000,000
Level 1 | Private credit    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 0 0
Level 2    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents 0 0
NDT fund investments 2,713,000,000 3,157,000,000
Rabbi trust investments 43,000,000 45,000,000
Investments in equities 0 0
Economic hedges 11,063,000,000 7,449,000,000
Effect of netting and allocation of collateral (10,361,000,000) (6,853,000,000)
Derivative assets subtotal 702,000,000 596,000,000
Total assets 3,458,000,000 3,798,000,000
Economic hedges (11,613,000,000) (8,021,000,000)
Effect of netting and allocation of collateral 11,283,000,000 7,657,000,000
Derivative liabilities subtotal (330,000,000) (364,000,000)
Deferred compensation obligation (110,000,000) (124,000,000)
Total liabilities measured at fair value (440,000,000) (488,000,000)
Total net assets 3,018,000,000 3,310,000,000
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents 0 0
Level 2 | Cash equivalents    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 163,000,000 165,000,000
Level 2 | Equities    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 1,072,000,000 1,426,000,000
Level 2 | Fixed income    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 1,478,000,000 1,566,000,000
Level 2 | Private credit    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 0 0
Level 3    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents 0 0
NDT fund investments 534,000,000 527,000,000
Rabbi trust investments 1,000,000 1,000,000
Investments in equities 0 0
Economic hedges 8,994,000,000 3,830,000,000
Effect of netting and allocation of collateral (5,950,000,000) (3,256,000,000)
Derivative assets subtotal 3,044,000,000 574,000,000
Total assets 3,579,000,000 1,102,000,000
Economic hedges (7,300,000,000) (4,062,000,000)
Effect of netting and allocation of collateral 6,429,000,000 3,628,000,000
Derivative liabilities subtotal (871,000,000) (434,000,000)
Deferred compensation obligation 0 0
Total liabilities measured at fair value (871,000,000) (434,000,000)
Total net assets 2,708,000,000 668,000,000
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents 0 0
Level 3 | Cash equivalents    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 0 0
Level 3 | Equities    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 0 0
Level 3 | Fixed income    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 401,000,000 395,000,000
Level 3 | Private credit    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments 133,000,000 132,000,000
Assets measured at NAV    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
NDT fund investments $ 7,421,000,000 $ 7,194,000,000