v3.26.1
Fair Value Measurements - MEC (Details) - Recurring - USD ($)
$ in Millions
Jun. 30, 2026
Dec. 31, 2025
Assets:    
Derivative asset, offset $ (6) $ (8)
Assets, fair value 6,393 3,566
Liabilities:    
Derivative liability, offset 59 84
Cash collateral receivable 53 76
U.S. government obligations    
Assets:    
Debt securities 840 326
Corporate obligations    
Assets:    
Debt securities 127 133
Municipal obligations    
Assets:    
Debt securities 1 2
U.S. companies    
Assets:    
Equity securities 560 549
International companies    
Assets:    
Equity securities 7 9
Investment funds    
Assets:    
Equity securities 265 283
Money market mutual funds    
Assets:    
Money market mutual funds 3,613 1,469
Level 1    
Assets:    
Assets, fair value 5,295 2,648
Level 1 | U.S. government obligations    
Assets:    
Debt securities 840 326
Level 1 | Corporate obligations    
Assets:    
Debt securities 0 0
Level 1 | Municipal obligations    
Assets:    
Debt securities 0 0
Level 1 | U.S. companies    
Assets:    
Equity securities 560 549
Level 1 | International companies    
Assets:    
Equity securities 7 9
Level 1 | Investment funds    
Assets:    
Equity securities 265 283
Level 1 | Money market mutual funds    
Assets:    
Money market mutual funds 3,613 1,469
Level 2    
Assets:    
Assets, fair value 1,088 916
Level 2 | U.S. government obligations    
Assets:    
Debt securities 0 0
Level 2 | Corporate obligations    
Assets:    
Debt securities 127 133
Level 2 | Municipal obligations    
Assets:    
Debt securities 1 2
Level 2 | U.S. companies    
Assets:    
Equity securities 0 0
Level 2 | International companies    
Assets:    
Equity securities 0 0
Level 2 | Investment funds    
Assets:    
Equity securities 0 0
Level 2 | Money market mutual funds    
Assets:    
Money market mutual funds 0 0
Level 3    
Assets:    
Assets, fair value 16 10
Level 3 | U.S. government obligations    
Assets:    
Debt securities 0 0
Level 3 | Corporate obligations    
Assets:    
Debt securities 0 0
Level 3 | Municipal obligations    
Assets:    
Debt securities 0 0
Level 3 | U.S. companies    
Assets:    
Equity securities 0 0
Level 3 | International companies    
Assets:    
Equity securities 0 0
Level 3 | Investment funds    
Assets:    
Equity securities 0 0
Level 3 | Money market mutual funds    
Assets:    
Money market mutual funds 0 0
Commodity derivatives    
Assets:    
Derivative asset, offset (6) (8)
Liabilities:    
Derivative liability, offset 58 83
Commodity derivatives | Level 1    
Assets:    
Derivative asset, gross 0 0
Liabilities:    
Commodity derivatives (13) (13)
Commodity derivatives | Level 2    
Assets:    
Derivative asset, gross 44 47
Liabilities:    
Commodity derivatives (134) (169)
Commodity derivatives | Level 3    
Assets:    
Derivative asset, gross 3 2
Liabilities:    
Commodity derivatives (68) (56)
MEC    
Assets:    
Assets, fair value 1,698 1,620
Liabilities:    
Cash collateral receivable 2 5
MEC | U.S. government obligations    
Assets:    
Debt securities 303 284
MEC | Corporate obligations    
Assets:    
Debt securities 127 133
MEC | Municipal obligations    
Assets:    
Debt securities 1 2
MEC | U.S. companies    
Assets:    
Equity securities 560 548
MEC | International companies    
Assets:    
Equity securities 7 9
MEC | Investment funds    
Assets:    
Equity securities 15 20
MEC | Money market mutual funds    
Assets:    
Money market mutual funds 680 622
MEC | Level 1    
Assets:    
Assets, fair value 1,565 1,483
MEC | Level 1 | U.S. government obligations    
Assets:    
Debt securities 303 284
MEC | Level 1 | Corporate obligations    
Assets:    
Debt securities 0 0
MEC | Level 1 | Municipal obligations    
Assets:    
Debt securities 0 0
MEC | Level 1 | U.S. companies    
Assets:    
Equity securities 560 548
MEC | Level 1 | International companies    
Assets:    
Equity securities 7 9
MEC | Level 1 | Investment funds    
Assets:    
Equity securities 15 20
MEC | Level 1 | Money market mutual funds    
Assets:    
Money market mutual funds 680 622
MEC | Level 2    
Assets:    
Assets, fair value 133 138
MEC | Level 2 | U.S. government obligations    
Assets:    
Debt securities 0 0
MEC | Level 2 | Corporate obligations    
Assets:    
Debt securities 127 133
MEC | Level 2 | Municipal obligations    
Assets:    
Debt securities 1 2
MEC | Level 2 | U.S. companies    
Assets:    
Equity securities 0 0
MEC | Level 2 | International companies    
Assets:    
Equity securities 0 0
MEC | Level 2 | Investment funds    
Assets:    
Equity securities 0  
MEC | Level 2 | Money market mutual funds    
Assets:    
Money market mutual funds 0 0
MEC | Level 3    
Assets:    
Assets, fair value 3 1
MEC | Level 3 | U.S. government obligations    
Assets:    
Debt securities 0 0
MEC | Level 3 | Corporate obligations    
Assets:    
Debt securities 0 0
MEC | Level 3 | Municipal obligations    
Assets:    
Debt securities 0 0
MEC | Level 3 | U.S. companies    
Assets:    
Equity securities 0 0
MEC | Level 3 | International companies    
Assets:    
Equity securities 0 0
MEC | Level 3 | Investment funds    
Assets:    
Equity securities 0  
MEC | Level 3 | Money market mutual funds    
Assets:    
Money market mutual funds 0 0
MEC | Commodity derivatives    
Assets:    
Derivative asset, gross 5 2
Derivative asset, offset (3) (2)
Liabilities:    
Commodity derivatives (15) (14)
Derivative liability, offset 5 7
MEC | Commodity derivatives | Level 1    
Assets:    
Derivative asset, gross 0 0
Liabilities:    
Commodity derivatives 0 0
MEC | Commodity derivatives | Level 2    
Assets:    
Derivative asset, gross 5 3
Liabilities:    
Commodity derivatives (15) (18)
MEC | Commodity derivatives | Level 3    
Assets:    
Derivative asset, gross 3 1
Liabilities:    
Commodity derivatives $ (5) $ (3)