Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions		Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle, net of income taxes	[1]	$ 0	$ 0	$ 0	$ (226)	$ 226	$ 0
Balance, beginning 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		717	0	0	717	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes		447	0	0	0	447	0
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments	[1]	(984)	0	0	0	(984)	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		(34)	0	0	0	(34)	0
Dividends to shareholders		(203)	0	0	(203)	0	0
Exercise of stock options		14	0	14	0	0	0
Share-based compensation		10	0	10	0	0	0
Purchases of treasury stock		(309)	0	0	0	0	(309)
Treasury stock reissued		29	0	13	0	0	16
Balance, end of period at Mar. 31, 2018		24,287	135	2,089	30,183	3,685	(11,805)
Balance, beginning 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		2,395
Balance, end of period at Sep. 30, 2018		23,234	135	2,151	31,461	1,909	(12,422)
Balance, beginning of period at Mar. 31, 2018		24,287	135	2,089	30,183	3,685	(11,805)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		832	0	0	832	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes		(138)	0	0	0	(138)	0
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments	[1]	(730)	0	0	0	(730)	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		34	0	0	0	34	0
Dividends to shareholders		(206)	0	0	(206)	0	0
Exercise of stock options		7	0	7	0	0	0
Share-based compensation		15	0	15	0	0	0
Purchases of treasury stock		(306)	0	0	0	0	(306)
Treasury stock reissued		4	0	6	0	0	(2)
Balance, end of period at Jun. 30, 2018		23,800	135	2,117	30,809	2,852	(12,113)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		845	0	0	845	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes		(347)	0	0	0	(347)	0
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments	[1]	(596)	0	0	0	(596)	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		1	0	0	0	1	0
Dividends to shareholders		(193)	0	0	(193)	0	0
Exercise of stock options		9	0	9	0	0	0
Share-based compensation		14	0	14	0	0	0
Purchases of treasury stock		(324)	0	0	0	0	(324)
Treasury stock reissued		26	0	11	0	0	15
Balance, end of period at Sep. 30, 2018		23,234	135	2,151	31,461	1,909	(12,422)
Balance, beginning of period at Dec. 31, 2018		23,462	135	2,177	31,788	2,151	(12,789)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		928	0	0	928	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes		(1)	0	0	0	(1)	0
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments		2,327	0	0	0	2,327	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		6	0	0	0	6	0
Dividends to shareholders		(203)	0	0	(203)	0	0
Exercise of stock options		11	0	11	0	0	0
Share-based compensation		8	0	8	0	0	0
Purchases of treasury stock		(517)	0	0	0	0	(517)
Treasury stock reissued		30	0	12	0	0	18
Balance, end of period at Mar. 31, 2019		26,049	135	2,208	32,513	4,481	(13,288)
Balance, beginning of period at Dec. 31, 2018		23,462	135	2,177	31,788	2,151	(12,789)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		2,523
Balance, end of period at Sep. 30, 2019		29,438	135	2,277	33,710	7,251	(13,935)
Balance, beginning of period at Mar. 31, 2019		26,049	135	2,208	32,513	4,481	(13,288)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		817	0	0	817	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes		393	0	0	0	393	0
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments		1,494	0	0	0	1,494	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		(3)	0	0	0	(3)	0
Dividends to shareholders		(200)	0	0	(200)	0	0
Exercise of stock options		12	0	12	0	0	0
Share-based compensation		15	0	15	0	0	0
Purchases of treasury stock		(358)	0	0	0	0	(358)
Treasury stock reissued		23	0	12	0	0	11
Balance, end of period at Jun. 30, 2019		28,241	135	2,247	33,130	6,364	(13,635)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		777	0	0	777	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes		(24)	0	0	0	(24)	0
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments		915	0	0	0	915	0
Unrealized gains (losses) on derivatives during period, net of income taxes		(6)	0	0	0	(6)	0
Pension liability adjustment during period, net of income taxes		2	0	0	0	2	0
Dividends to shareholders		(197)	0	0	(197)	0	0
Exercise of stock options		3	0	3	0	0	0
Share-based compensation		15	0	15	0	0	0
Purchases of treasury stock		(311)	0	0	0	0	(311)
Treasury stock reissued		23	0	12	0	0	11
Balance, end of period at Sep. 30, 2019		$ 29,438	$ 135	$ 2,277	$ 33,710	$ 7,251	$ (13,935)

[1] See Note 1 of the Notes to the Consolidated Financial Statements in the Company's 2018 Annual Report on Form 10-K