v3.25.2
Fair Value of Financial Assets and Liabilities - Fair Value Measurement of Assets and Liabilities, Recurring (Details) - USD ($)
$ in Millions
Jun. 30, 2025
Dec. 31, 2024
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Derivative asset notational amounts $ 1,514 $ 1,119
Cash and Cash Equivalents | Constellation Energy Generation, LLC    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 1,943 2,924
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 1,943 2,924
Cash and Cash Equivalents | CEG Parent    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 51 130
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 51 130
Restricted cash | Constellation Energy Generation, LLC    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 59 71
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 59 71
Cash | CEG Parent    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 9 4
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 9 4
NDT fund investments subtotal    
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Net liabilities 135 148
Fair Value, Recurring    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 38 120
Deferred compensation obligation (111) (93)
Total liabilities measured at fair value (937) (959)
Total net assets 18,874 18,186
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 38 120
Fair Value, Recurring | Mark-to-market derivative liabilities subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities (826) (866)
Fair Value, Recurring | Economic hedges    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities (12,206) (9,462)
Fair Value, Recurring | Effect of netting and allocation of collateral    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities 11,380 8,596
Fair Value, Recurring | NDT fund investments subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 18,329 17,321
Fair Value, Recurring | Cash equivalents    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 660 350
Fair Value, Recurring | Equities NDT    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 7,394 7,127
Fair Value, Recurring | Fixed income    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 4,193 3,919
Fair Value, Recurring | Private credit    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 127 134
Fair Value, Recurring | Rabbi trust investments    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 99 100
Fair Value, Recurring | Investments in equities    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 92 389
Fair Value, Recurring | Mark-to-market derivative assets subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets 1,253 1,215
Fair Value, Recurring | Economic hedges    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets 11,786 9,225
Fair Value, Recurring | Effect of netting and allocation of collateral    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets (10,533) (8,010)
Total assets measured at fair value | Fair Value, Recurring    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Total assets 19,811 19,145
Level 1 | Fair Value, Recurring    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 38 120
Total assets 8,822 8,254
Deferred compensation obligation 0 0
Total liabilities measured at fair value (60) (42)
Total net assets 8,762 8,212
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 38 120
Level 1 | Fair Value, Recurring | Mark-to-market derivative liabilities subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities (60) (42)
Level 1 | Fair Value, Recurring | Economic hedges    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities (1,417) (1,222)
Level 1 | Fair Value, Recurring | Effect of netting and allocation of collateral    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities 1,357 1,180
Level 1 | Fair Value, Recurring | NDT fund investments subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 8,450 7,506
Level 1 | Fair Value, Recurring | Cash equivalents    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 490 187
Level 1 | Fair Value, Recurring | Equities NDT    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 5,730 5,230
Level 1 | Fair Value, Recurring | Fixed income    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 2,230 2,089
Level 1 | Fair Value, Recurring | Private credit    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 0 0
Level 1 | Fair Value, Recurring | Rabbi trust investments    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 58 58
Level 1 | Fair Value, Recurring | Investments in equities    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 92 389
Level 1 | Fair Value, Recurring | Mark-to-market derivative assets subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets 184 181
Level 1 | Fair Value, Recurring | Economic hedges    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets 1,402 1,278
Level 1 | Fair Value, Recurring | Effect of netting and allocation of collateral    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets (1,218) (1,097)
Level 2 | Fair Value, Recurring    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 0 0
Total assets 3,792 4,079
Deferred compensation obligation (111) (93)
Total liabilities measured at fair value (277) (398)
Total net assets 3,515 3,681
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 0 0
Level 2 | Fair Value, Recurring | Mark-to-market derivative liabilities subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities (166) (305)
Level 2 | Fair Value, Recurring | Economic hedges    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities (6,424) (5,462)
Level 2 | Fair Value, Recurring | Effect of netting and allocation of collateral    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities 6,258 5,157
Level 2 | Fair Value, Recurring | NDT fund investments subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 3,420 3,522
Level 2 | Fair Value, Recurring | Cash equivalents    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 170 163
Level 2 | Fair Value, Recurring | Equities NDT    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 1,663 1,897
Level 2 | Fair Value, Recurring | Fixed income    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 1,587 1,462
Level 2 | Fair Value, Recurring | Private credit    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 0 0
Level 2 | Fair Value, Recurring | Rabbi trust investments    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 40 41
Level 2 | Fair Value, Recurring | Investments in equities    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 0 0
Level 2 | Fair Value, Recurring | Mark-to-market derivative assets subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets 332 516
Level 2 | Fair Value, Recurring | Economic hedges    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets 6,166 5,306
Level 2 | Fair Value, Recurring | Effect of netting and allocation of collateral    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets (5,834) (4,790)
Level 3 | Fair Value, Recurring    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 0 0
Total assets 1,242 1,021
Deferred compensation obligation 0 0
Total liabilities measured at fair value (600) (519)
Total net assets 642 502
Footnotes To Fair Value Assets And Liabilities Measured On Recurring Basis [Abstract]    
Cash equivalents, fair value disclosure 0 0
Level 3 | Fair Value, Recurring | Mark-to-market derivative liabilities subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities (600) (519)
Level 3 | Fair Value, Recurring | Economic hedges    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities (4,365) (2,778)
Level 3 | Fair Value, Recurring | Effect of netting and allocation of collateral    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative liabilities 3,765 2,259
Level 3 | Fair Value, Recurring | NDT fund investments subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 504 502
Level 3 | Fair Value, Recurring | Cash equivalents    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 0 0
Level 3 | Fair Value, Recurring | Equities NDT    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 1 0
Level 3 | Fair Value, Recurring | Fixed income    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 376 368
Level 3 | Fair Value, Recurring | Private credit    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 127 134
Level 3 | Fair Value, Recurring | Rabbi trust investments    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 1 1
Level 3 | Fair Value, Recurring | Investments in equities    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Investments, fair value disclosure 0 0
Level 3 | Fair Value, Recurring | Mark-to-market derivative assets subtotal    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets 737 518
Level 3 | Fair Value, Recurring | Economic hedges    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets 4,218 2,641
Level 3 | Fair Value, Recurring | Effect of netting and allocation of collateral    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Mark-to-market derivative assets (3,481) (2,123)
Assets measured at NAV | Fair Value, Recurring    
Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract]    
Total assets $ 5,955 $ 5,791