Consolidated Statements of Shareholders' Equity - USD ($) $ in Millions		Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income (loss)	Treasury stock	Cumulative effect, period of adoption, adjustment	Cumulative effect, period of adoption, adjustment Common stock	Cumulative effect, period of adoption, adjustment Additional paid-in capital	Cumulative effect, period of adoption, adjustment Retained earnings	Cumulative effect, period of adoption, adjustment Accumulated other comprehensive income (loss)	Cumulative effect, period of adoption, adjustment Treasury stock	Cumulative effect, period of adoption, adjusted balance	Cumulative effect, period of adoption, adjusted balance Common stock	Cumulative effect, period of adoption, adjusted balance Additional paid-in capital	Cumulative effect, period of adoption, adjusted balance Retained earnings	Cumulative effect, period of adoption, adjusted balance Accumulated other comprehensive income (loss)	Cumulative effect, period of adoption, adjusted balance Treasury stock
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		1,745
Balance, end of period at Jun. 30, 2019		28,241	135	2,247	33,130	6,364	(13,635)
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)
Balance, beginning of period at Dec. 31, 2019		28,959	135	2,313	34,291	6,615	(14,395)							$ 29,751	$ 135	$ 2,313	$ 34,235	$ 7,463	$ (14,395)
Balance, beginning of period (Accounting Standards Update 2016-13) at Dec. 31, 2019	[1]							$ (56)	$ 0	$ 0	$ (56)	$ 0	$ 0
Balance, beginning of period (Accounting Standards Update 2019-04) at Dec. 31, 2019	[1]							848	0	0	0	848	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		566	0	0	566	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes		80	0	0	0	80	0
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments		(3,353)	0	0	0	(3,353)	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		0	0	0	0	0	0
Dividends to shareholders		(202)	0	0	(202)	0	0
Exercise of stock options		5	0	5	0	0	0
Share-based compensation		7	0	7	0	0	0
Purchases of treasury stock		(476)	0	0	0	0	(476)
Treasury stock reissued		26	0	9	0	0	17
Balance, end of period at Mar. 31, 2020		26,402	135	2,334	34,599	4,188	(14,854)
Balance, beginning of period at Dec. 31, 2019		28,959	135	2,313	34,291	6,615	(14,395)							$ 29,751	$ 135	$ 2,313	$ 34,235	$ 7,463	$ (14,395)
Balance, beginning of period (Accounting Standards Update 2016-13) at Dec. 31, 2019	[1]							(56)	0	0	(56)	0	0
Balance, beginning of period (Accounting Standards Update 2019-04) at Dec. 31, 2019	[1]							$ 848	$ 0	$ 0	$ 0	$ 848	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		1,370
Balance, end of period at Jun. 30, 2020		29,420	135	2,358	35,204	6,750	(15,027)
Balance, beginning of period at Mar. 31, 2020		26,402	135	2,334	34,599	4,188	(14,854)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings		805	0	0	805	0	0
Unrealized foreign currency translation gains (losses) during period, net of income taxes		74	0	0	0	74	0
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments		2,489	0	0	0	2,489	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		0	0	0	0	0	0
Dividends to shareholders		(200)	0	0	(200)	0	0
Exercise of stock options		1	0	1	0	0	0
Share-based compensation		16	0	16	0	0	0
Purchases of treasury stock		(189)	0	0	0	0	(189)
Treasury stock reissued		23	0	7	0	0	16
Balance, end of period at Jun. 30, 2020		$ 29,420	$ 135	$ 2,358	$ 35,204	$ 6,750	$ (15,027)

[1] See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2020.