Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock
Balance, beginning of period at Dec. 31, 2016	$ 20,482	$ 135	$ 1,908	$ 25,981	$ 2,630	$ (10,172)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	4,604	0	0	4,604	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes	233	0	0	0	233	0
Unrealized gains (losses) on fixed maturity securities during the period, net of income taxes and reclassification adjustments	1,159	0	0	0	1,159	0
Unrealized gains (losses) on derivatives during period, net of income taxes	1	0	0	0	1	0
Pension liability adjustment during period, net of income taxes	5	0	0	0	5	0
Dividends to shareholders	(690)	0	0	(690)	0	0
Exercise of stock options	38	0	38	0	0	0
Share-based compensation	51	0	51	0	0	0
Purchases of treasury stock	(1,391)	0	0	0	0	(1,391)
Treasury stock reissued	106	0	55	0	0	51
Balance, end of period at Dec. 31, 2017	24,598	135	2,052	29,895	4,028	(11,512)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	2,920	0	0	2,920	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes	228	0	0	0	228	0
Unrealized gains (losses) on fixed maturity securities during the period, net of income taxes and reclassification adjustments	(2,316)	0	0	0	(2,316)	0
Unrealized gains (losses) on derivatives during period, net of income taxes	2	0	0	0	2	0
Pension liability adjustment during period, net of income taxes	(17)	0	0	0	(17)	0
Dividends to shareholders	(801)	0	0	(801)	0	0
Exercise of stock options	34	0	34	0	0	0
Share-based compensation	54	0	54	0	0	0
Purchases of treasury stock	(1,317)	0	0	0	0	(1,317)
Treasury stock reissued	77	0	37	0	0	40
Balance, end of period at Dec. 31, 2018	23,462	135	2,177	31,788	2,151	(12,789)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle, net of income taxes	0	0	0	(226)	226	0
Net earnings	3,304	0	0	3,304	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes	224	0	0	0	224	0
Unrealized gains (losses) on fixed maturity securities during the period, net of income taxes and reclassification adjustments	4,314	0	0	0	4,314	0
Unrealized gains (losses) on derivatives during period, net of income taxes	(9)	0	0	0	(9)	0
Pension liability adjustment during period, net of income taxes	(65)	0	0	0	(65)	0
Dividends to shareholders	(801)	0	0	(801)	0	0
Exercise of stock options	29	0	29	0	0	0
Share-based compensation	54	0	54	0	0	0
Purchases of treasury stock	(1,656)	0	0	0	0	(1,656)
Treasury stock reissued	103	0	53	0	0	50
Balance, end of period at Dec. 31, 2019	$ 28,959	$ 135	$ 2,313	$ 34,291	$ 6,615	$ (14,395)