Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance as of beginning-of-period at Dec. 31, 2023		$ 986	$ 4,605	$ 4,778	$ (3,476)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock			0
Stock compensation/issued for benefit plans			36
Net income (loss)	$ 2,116			2,116
Preferred stock dividends declared				(46)
Common stock dividends declared				(157)
Other comprehensive income (loss), net of tax	(893)				(893)
Balance as of end-of-period at Jun. 30, 2024	7,949	986	4,641	6,691	(4,369)
Balance as of beginning-of-period at Mar. 31, 2024		986	4,624	5,887	(3,951)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock			0
Stock compensation/issued for benefit plans			17
Net income (loss)	895			895
Preferred stock dividends declared				(11)
Common stock dividends declared				(80)
Other comprehensive income (loss), net of tax	(418)				(418)
Balance as of end-of-period at Jun. 30, 2024	7,949	986	4,641	6,691	(4,369)
Balance as of beginning-of-period at Dec. 31, 2024	8,269	986	4,674	7,645	(5,036)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock			825
Stock compensation/issued for benefit plans			46
Net income (loss)	(23)			(23)
Preferred stock dividends declared				(46)
Common stock dividends declared				(167)
Other comprehensive income (loss), net of tax	644				644
Balance as of end-of-period at Jun. 30, 2025	9,548	986	5,545	7,409	(4,392)
Balance as of beginning-of-period at Mar. 31, 2025		986	4,703	6,810	(4,306)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock			825
Stock compensation/issued for benefit plans			17
Net income (loss)	699			699
Preferred stock dividends declared				(11)
Common stock dividends declared				(89)
Other comprehensive income (loss), net of tax	(86)				(86)
Balance as of end-of-period at Jun. 30, 2025	$ 9,548	$ 986	$ 5,545	$ 7,409	$ (4,392)