Consolidated Statement of Changes in Equity (Unaudited) - USD ($) $ in Millions	Total	Total	Common Shares	Common Stock and Capital Surplus	Retained Earnings	Accumulated Other Comp. Income	Noncontrolling interests	Cumulative effect adjustment in period of adoption Retained Earnings
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	$ 6,269	$ 6,269		$ 1,397	$ 4,009	$ 863	$ 0	$ 7
Beginning Balance, shares at Dec. 31, 2019			90,303,686
Beginning Balance at Dec. 31, 2019	6,269	6,269		1,397	4,009	863	0	$ 7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (losses) attributable to parent	40	40			40
Net earnings loss attributable to noncontrolling interests	(13)
Net earnings, including noncontrolling interests	27
Net earnings (losses) including portion attributable to nonredeemable noncontrolling interest	40						0
Other comprehensive income (loss), attributable to parent		366				366
Other comprehensive income (loss) including portion attributable to nonredeemable noncontrolling interest	366
Dividends	(120)	(120)			(120)
Shares issued:
Exercise of stock options, shares			229,208
Exercise of stock options	10	10		10
Restricted stock awards, shares			227,867
Other benefit plans, shares			105,318
Other benefit plans	7	7		7
Dividend reinvestment plan, shares			7,251
Dividend reinvestment plan	1	1		1
Stock-based compensation expense	15	15		15
Shares acquired and retired, shares			(3,468,107)
Shares acquired and retired	(233)	(233)		(54)	(179)
Shares exchanged — benefit plans, shares			(97,731)
Shares exchanged — benefit plans	(11)	(11)		(2)	(9)
Forfeitures of restricted stock, shares			(40,910)
Other	(11)	(11)		(4)	(11)	4	0
Ending Balance, shares at Sep. 30, 2020			87,266,582
Ending Balance at Sep. 30, 2020	6,340	6,340		1,370	3,737	1,233	0
Beginning Balance, Redeemable Noncontrolling Interests at Dec. 31, 2019	0
Redeemable Noncontrolling Interest, Equity, Carrying Amount [Abstract]
Net earnings attributable to redeemable noncontrolling interests	(13)
Other comprehensive income (loss) attributable to redeemable noncontrolling interests	2
Other	11
Ending Balance, Redeemable Noncontrolling Interests at Sep. 30, 2020	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	6,126	6,126		1,388	3,685	1,053	0
Beginning Balance, shares at Jun. 30, 2020			88,659,407
Beginning Balance at Jun. 30, 2020	6,126	6,126		1,388	3,685	1,053	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (losses) attributable to parent	164	164			164
Net earnings loss attributable to noncontrolling interests	0
Net earnings, including noncontrolling interests	164
Net earnings (losses) including portion attributable to nonredeemable noncontrolling interest	164						0
Other comprehensive income (loss), attributable to parent		176				176
Other comprehensive income (loss) including portion attributable to nonredeemable noncontrolling interest	176
Dividends	(39)	(39)			(39)
Shares issued:
Exercise of stock options, shares			19,865
Exercise of stock options	1	1		1
Restricted stock awards, shares			0
Other benefit plans, shares			38,822
Other benefit plans	2	2		2
Dividend reinvestment plan, shares			2,901
Dividend reinvestment plan	1	1		1
Stock-based compensation expense	5	5		5
Shares acquired and retired, shares			(1,447,588)
Shares acquired and retired	(96)	(96)		(23)	(73)
Shares exchanged — benefit plans, shares			(1,337)
Shares exchanged — benefit plans	0	0		0	0
Forfeitures of restricted stock, shares			(5,488)
Other, shares			0
Other	0			(4)	0	4	0
Ending Balance, shares at Sep. 30, 2020			87,266,582
Ending Balance at Sep. 30, 2020	6,340	6,340		1,370	3,737	1,233	0
Ending Balance, Redeemable Noncontrolling Interests at Sep. 30, 2020	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	6,340	6,340		1,370	3,737	1,233	0
Cumulative effect of accounting change	$ 6,789	6,789		1,367	4,149	1,273	0
Beginning Balance, shares at Dec. 31, 2020	86,345,246		86,345,246
Beginning Balance at Dec. 31, 2020	$ 6,789	6,789		1,367	4,149	1,273	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (losses) attributable to parent	1,640	1,640			1,640
Net earnings loss attributable to noncontrolling interests	0						0
Net earnings, including noncontrolling interests	1,640
Other comprehensive income (loss), attributable to parent		(1,113)				(1,113)
Other comprehensive income (loss) including portion attributable to nonredeemable noncontrolling interest	(1,113)
Dividends	(1,826)	(1,826)			(1,826)
Shares issued:
Exercise of stock options, shares			1,118,586
Exercise of stock options	55	55		55
Restricted stock awards, shares			207,020
Other benefit plans, shares			60,494
Other benefit plans	7	7		7
Dividend reinvestment plan, shares			42,926
Dividend reinvestment plan	5	5		5
Stock-based compensation expense	11	11		11
Shares acquired and retired, shares			(2,769,182)
Shares acquired and retired	(318)	(318)		(44)	(274)
Shares exchanged — benefit plans, shares			(91,926)
Shares exchanged — benefit plans	$ (10)	(10)		(1)	(9)
Forfeitures of restricted stock, shares			(118,156)
Ending Balance, shares at Sep. 30, 2021	84,795,008		84,795,008
Ending Balance at Sep. 30, 2021	$ 5,240	5,240		1,400	3,680	160	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	5,601	5,601		1,388	4,023	190	0
Beginning Balance, shares at Jun. 30, 2021			84,713,927
Beginning Balance at Jun. 30, 2021	5,601	5,601		1,388	4,023	190	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (losses) attributable to parent	219	219			219
Net earnings loss attributable to noncontrolling interests	0						0
Net earnings, including noncontrolling interests	219
Other comprehensive income (loss), attributable to parent		(30)				(30)
Other comprehensive income (loss) including portion attributable to nonredeemable noncontrolling interest	(30)
Dividends	(551)	(551)			(551)
Shares issued:
Exercise of stock options, shares			153,842
Exercise of stock options	6	6		6
Restricted stock awards, shares			0
Other benefit plans, shares			17,029
Other benefit plans	2	2		2
Dividend reinvestment plan, shares			6,272
Dividend reinvestment plan	1	1		1
Stock-based compensation expense	4	4		4
Shares acquired and retired, shares			(94,960)
Shares acquired and retired	(12)	(12)		(1)	(11)
Shares exchanged — benefit plans, shares			(562)
Shares exchanged — benefit plans	$ 0	0		0	0
Forfeitures of restricted stock, shares			(540)
Ending Balance, shares at Sep. 30, 2021	84,795,008		84,795,008
Ending Balance at Sep. 30, 2021	$ 5,240	5,240		1,400	3,680	160	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	$ 5,240	$ 5,240		$ 1,400	$ 3,680	$ 160	$ 0