Statements of Changes in Shareholder's Equity (Unaudited) - MEC - USD ($) $ in Millions	Total	Additional Paid-in Capital	Retained Earnings	MEC	MEC Common Stock	MEC Additional Paid-in Capital	MEC Retained Earnings
Balance at Dec. 31, 2021				$ 8,960	$ 0	$ 561	$ 8,399
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 2,768			451			451
Other equity transactions	(5)	$ 1	$ (12)
Balance at Jun. 30, 2022				9,411	0	561	8,850
Balance at Mar. 31, 2022				9,204	0	561	8,643
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	2,897			207			207
Other equity transactions	(10)	$ 1	$ (11)
Balance at Jun. 30, 2022				9,411	0	561	8,850
Balance at Dec. 31, 2022	46,832			9,645	0	561	9,084
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	2,064			478			478
Dividends declared				(100)			(100)
Other equity transactions	(8)			1			1
Balance at Jun. 30, 2023	49,183			10,024	0	561	9,463
Balance at Mar. 31, 2023				9,788	0	561	9,227
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,075			236			236
Other equity transactions	(8)
Balance at Jun. 30, 2023	$ 49,183			$ 10,024	$ 0	$ 561	$ 9,463