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			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]
Issuance of common stock			0
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)
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			75
Net income (loss)	423			423
Preferred stock dividends declared				(80)
Common stock dividends declared				(257)
Other comprehensive income (loss), net of tax	1,197				1,197
Balance as of end-of-period at Sep. 30, 2025	10,452	986	5,574	7,731	(3,839)
Balance as of beginning-of-period at Jun. 30, 2025		986	5,545	7,409	(4,392)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock			0
Stock compensation/issued for benefit plans			29
Net income (loss)	445			445
Preferred stock dividends declared				(34)
Common stock dividends declared				(89)
Other comprehensive income (loss), net of tax	553				553
Balance as of end-of-period at Sep. 30, 2025	$ 10,452	$ 986	$ 5,574	$ 7,731	$ (3,839)