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, 2022		$ 986	$ 4,544	$ 5,924	$ (6,352)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation/issued for benefit plans			47
Net income (loss)	$ 483			483
Preferred stock dividends declared				(71)
Common stock dividends declared				(234)
Other comprehensive income (loss), net of tax	(2,128)				(2,128)
Balance as of end-of-period at Sep. 30, 2023	3,199	986	4,591	6,102	(8,480)
Balance as of beginning-of-period at Jun. 30, 2023		986	4,575	5,362	(5,104)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation/issued for benefit plans			16
Net income (loss)	853			853
Preferred stock dividends declared				(34)
Common stock dividends declared				(79)
Other comprehensive income (loss), net of tax	(3,376)				(3,376)
Balance as of end-of-period at Sep. 30, 2023	3,199	986	4,591	6,102	(8,480)
Balance as of beginning-of-period 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			55
Net income (loss)	1,588			1,588
Preferred stock dividends declared				(80)
Common stock dividends declared				(237)
Other comprehensive income (loss), net of tax	794				794
Balance as of end-of-period at Sep. 30, 2024	9,013	986	4,660	6,049	(2,682)
Balance as of beginning-of-period at Jun. 30, 2024		986	4,641	6,691	(4,369)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation/issued for benefit plans			19
Net income (loss)	(528)			(528)
Preferred stock dividends declared				(34)
Common stock dividends declared				(80)
Other comprehensive income (loss), net of tax	1,687				1,687
Balance as of end-of-period at Sep. 30, 2024	$ 9,013	$ 986	$ 4,660	$ 6,049	$ (2,682)