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, 2020	$ 13,598	$ 0	$ 0	$ 8,642	$ (1,309)	$ 6,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	878					878
Other comprehensive income (loss)	(23)				(23)
Stock-based compensation	8			8
Dividends paid (Note 10)	(661)					(661)
Balance at end of period at Mar. 31, 2021	13,800	0	0	8,650	(1,332)	6,482
Balance at beginning of period at Dec. 31, 2020	13,598	0	0	8,642	(1,309)	6,265
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	2,058
Other comprehensive income (loss)	103
Balance at end of period at Jun. 30, 2021	14,465	0	0	8,668	(1,206)	7,003
Balance at beginning of period at Mar. 31, 2021	13,800	0	0	8,650	(1,332)	6,482
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,180					1,180
Other comprehensive income (loss)	126				126
Stock-based compensation	18			18
Dividends paid (Note 10)	(600)					(600)
Dividends declared on preferred stock (Note 10)	(59)					(59)
Balance at end of period at Jun. 30, 2021	14,465	0	0	8,668	(1,206)	7,003
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)	1,791
Other comprehensive income (loss)	46
Dividends declared on preferred stock (Note 10)	(59)
Balance at end of period at Jun. 30, 2022	14,844	0	0	8,713	(1,226)	7,357
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