Consolidated Statement of Changes in Equity - USD ($) $ in Millions	Total	Cumulative effect, period of adoption, adjustment	Total	Total Cumulative effect, period of adoption, adjustment	Common Shares	Common Stock and Capital Surplus	Retained Earnings	Retained Earnings Cumulative effect, period of adoption, adjustment	Accumulated Other Comprehensive Inc. (Loss)	Noncontrolling Interests
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	$ 6,269	$ 7	$ 6,269	$ 7		$ 1,397	$ 4,009	$ 7	$ 863	$ 0
Beginning Balance, shares at Dec. 31, 2019					90,303,686
Beginning Balance at Dec. 31, 2019	6,269	$ 7	6,269	$ 7		1,397	4,009	$ 7	863	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss) attributable to parent	732		732				732
Net income (loss), including portion attributable to nonredeemable noncontrolling interest	734									2
Other comprehensive income (loss)	416		414						414	0
Other comprehensive income (loss), including portion attributable to noncontrolling interest	414
Dividends	(336)		(336)				(336)
Shares issued:
Exercise of stock options, shares					328,471
Exercise of stock options	14		14			14
Restricted stock awards, shares					227,867
Restricted stock awards	0		0			0
Other benefit plans, shares					143,270
Other benefit plans	10		10			10
Dividend reinvestment plan, shares					18,690
Dividend reinvestment plan	2		2			2
Stock-based compensation expense	20		20			20
Shares acquired and retired, shares					(4,531,394)
Shares acquired and retired	(313)		(313)			(70)	(243)
Shares exchanged — benefit plans, shares					(101,663)
Shares exchanged — benefit plans	(11)		(11)			(2)	(9)
Forfeitures of restricted stock, shares					(43,681)
Other	(21)		(19)			(4)	(11)		(4)	(2)
Ending Balance, shares at Dec. 31, 2020					86,345,246
Ending Balance at Dec. 31, 2020	6,789		6,789			1,367	4,149		1,273	0
Beginning Balance, redeemable noncontrolling interests at Dec. 31, 2019	0
Redeemable Noncontrolling Interest, Equity, Carrying Amount [Abstract]
Net income (loss) attributable to redeemable noncontrolling interest	(13)
Other comprehensive income (loss), net of tax attributable to redeemable noncontrolling interests	2
Other	11
Ending Balance, redeemable noncontrolling interests at Dec. 31, 2020	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	6,789		6,789			1,367	4,149		1,273	0
Net income (loss) attributable to parent	1,995		1,995				1,995
Net income (loss), including portion attributable to nonredeemable noncontrolling interest	1,995									0
Other comprehensive income (loss)	(1,154)		(1,154)						(1,154)	0
Other comprehensive income (loss), including portion attributable to noncontrolling interest	(1,154)
Dividends	(2,382)		(2,382)				(2,382)
Shares issued:
Exercise of stock options, shares					1,208,964
Exercise of stock options	59		59			59
Restricted stock awards, shares					207,020
Restricted stock awards	0		0			0
Other benefit plans, shares					81,286
Other benefit plans	10		10			10
Dividend reinvestment plan, shares					69,095
Dividend reinvestment plan	8		8			8
Stock-based compensation expense	16		16			16
Shares acquired and retired, shares					(2,777,684)
Shares acquired and retired	(319)		(319)			(44)	(275)
Shares exchanged — benefit plans, shares					(92,209)
Shares exchanged — benefit plans	$ (10)		(10)			(1)	(9)
Forfeitures of restricted stock, shares					(120,753)
Ending Balance, shares at Dec. 31, 2021	84,920,965				84,920,965
Ending Balance at Dec. 31, 2021	$ 5,012		5,012			1,415	3,478		119	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	5,012		5,012			1,415	3,478		119	0
Net income (loss) attributable to parent	898		898				898
Net income (loss), including portion attributable to nonredeemable noncontrolling interest	898									0
Other comprehensive income (loss)	(662)		(662)						(662)	0
Other comprehensive income (loss), including portion attributable to noncontrolling interest	(662)
Dividends	$ (1,217)		(1,217)				(1,217)
Shares issued:
Exercise of stock options, shares	182,054				182,054
Exercise of stock options	$ 7		7			7
Restricted stock awards, shares					151,080
Restricted stock awards	0		0			0
Other benefit plans, shares					78,460
Other benefit plans	10		10			10
Dividend reinvestment plan, shares					33,794
Dividend reinvestment plan	4		4			4
Stock-based compensation expense	19		19			19
Shares acquired and retired, shares					(89,368)
Shares acquired and retired	(11)		(11)			(1)	(10)
Shares exchanged — benefit plans, shares					(57,420)
Shares exchanged — benefit plans	$ (8)		(8)			(1)	(7)
Forfeitures of restricted stock, shares					(15,559)
Ending Balance, shares at Dec. 31, 2022	85,204,006				85,204,006
Ending Balance at Dec. 31, 2022	$ 4,052		4,052			1,453	3,142		(543)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	$ 4,052		$ 4,052			$ 1,453	$ 3,142		$ (543)	$ 0