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-year at Dec. 31, 2022		$ 986	$ 4,544	$ 5,924	$ (6,352)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation/issued for benefit plans			16
Net income (loss)	$ (881)			(881)
Preferred stock dividends declared				(25)
Common stock dividends declared				(78)
Other comprehensive income (loss), net of tax	2,598				2,598
Balance as of end-of-period at Mar. 31, 2023	6,732	986	4,560	4,940	(3,754)
Balance as of beginning-of-year at Dec. 31, 2023	6,893	986	4,605	4,778	(3,476)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation/issued for benefit plans			19
Net income (loss)	1,222			1,222
Preferred stock dividends declared				(34)
Common stock dividends declared				(79)
Other comprehensive income (loss), net of tax	(475)				(475)
Balance as of end-of-period at Mar. 31, 2024	$ 7,546	$ 986	$ 4,624	$ 5,887	$ (3,951)