CONSOLIDATED STATEMENT OF CHANGES IN EQUITY (UNAUDITED) - USD ($) $ in Millions	Total	Preferred stock	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss
Balance at beginning of period at Dec. 31, 2022		$ 265
Balance at beginning of period, common equity at Dec. 31, 2022			$ 0	$ 12,740	$ 1,683	$ (2,575)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee benefit plans				(4)
Net income	$ 217				217
Other comprehensive income (loss), net of tax	365					365
Balance at end of period, common equity at Mar. 31, 2023	12,426		0	12,736	1,900	(2,210)
Balance at end of period at Mar. 31, 2023	12,691	265
Balance at beginning of period at Dec. 31, 2023	11,639	265
Balance at beginning of period, common equity at Dec. 31, 2023	11,374		0	12,740	560	(1,926)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Employee benefit plans				0
Net income	225				225
Other comprehensive income (loss), net of tax	(108)					(108)
Balance at end of period, common equity at Mar. 31, 2024	11,491		$ 0	$ 12,740	$ 785	$ (2,034)
Balance at end of period at Mar. 31, 2024	$ 11,756	$ 265