Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common Stock	Preferred Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings
Balance at beginning of period at Dec. 31, 2021	$ 13,794	$ 0	$ 0	$ 8,692	$ (1,273)	$ 6,375
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	962					962
Other comprehensive income (loss)	238				238
Stock-based compensation	10			10
Balance at end of period at Mar. 31, 2022	15,004	0	0	8,701	(1,034)	7,337
Balance at beginning of period at Dec. 31, 2021	13,794	0	0	8,692	(1,273)	6,375
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	2,479
Other comprehensive income (loss)	(130)
Balance at end of period at Sep. 30, 2022	15,091	0	0	8,723	(1,402)	7,770
Balance at beginning of period at Mar. 31, 2022	15,004	0	0	8,701	(1,034)	7,337
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	829					829
Other comprehensive income (loss)	(192)				(192)
Stock-based compensation	11			11
Dividends paid (Note 10)	(750)					(750)
Dividends declared on preferred stock (Note 10)	(59)					(59)
Balance at end of period at Jun. 30, 2022	14,844	0	0	8,713	(1,226)	7,357
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	688					688
Other comprehensive income (loss)	(176)				(176)
Stock-based compensation	10			10
Dividends paid (Note 10)	(275)					(275)
Balance at end of period at Sep. 30, 2022	15,091	0	0	8,723	(1,402)	7,770
Balance at beginning of period at Dec. 31, 2022	15,010	0	0	8,742	(1,373)	7,641
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	584					584
Other comprehensive income (loss)	49				49
Stock-based compensation	7			7
Dividends paid (Note 10)	(450)					(450)
Balance at end of period at Mar. 31, 2023	15,201	0	0	8,749	(1,323)	7,775
Balance at beginning of period at Dec. 31, 2022	15,010	0	0	8,742	(1,373)	7,641
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,713
Other comprehensive income (loss)	70
Balance at end of period at Sep. 30, 2023	15,412	0	0	8,770	(1,302)	7,944
Balance at beginning of period at Mar. 31, 2023	15,201	0	0	8,749	(1,323)	7,775
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	571					571
Other comprehensive income (loss)	11				11
Stock-based compensation	11			11
Dividends paid (Note 10)	(450)					(450)
Dividends declared on preferred stock (Note 10)	(59)					(59)
Balance at end of period at Jun. 30, 2023	15,284	0	0	8,760	(1,312)	7,837
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	558					558
Other comprehensive income (loss)	10				10
Stock-based compensation	10			10
Dividends paid (Note 10)	(450)					(450)
Balance at end of period at Sep. 30, 2023	$ 15,412	$ 0	$ 0	$ 8,770	$ (1,302)	$ 7,944