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			$ 135	$ 1,908	$ 25,981	$ 2,630	$ (10,172)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options				28
Share-based compensation				24
Treasury stock reissued				20			30
Net earnings		$ 1,305			1,305
Dividends to shareholders					(344)
Unrealized foreign currency translation gains (losses) during period, net of income taxes						403
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments	[1]					368
Unrealized gains (losses) on derivatives during period, net of income taxes						1
Pension liability adjustment during period, net of income taxes						(1)
Purchases of treasury stock							(813)
Balance, end of period at Jun. 30, 2017		21,503	135	1,980	26,942	3,401	(10,955)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of change in accounting principle, net of income taxes | Accounting Standards Update 2016-01	[1]				0	0
Cumulative effect of change in accounting principle, net of income taxes | Accounting Standards Update 2018-02	[1]				0	0
Cumulative effect of change in accounting principle, net of income taxes | Accounting Standards Update 2016-01	[1]				148
Cumulative effect of change in accounting principle, net of income taxes | Accounting Standards Update 2018-02	[1]				(374)
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]
Exercise of stock options				21
Share-based compensation				25
Treasury stock reissued				19			14
Net earnings		1,550			1,550
Dividends to shareholders					(410)
Unrealized foreign currency translation gains (losses) during period, net of income taxes						309
Unrealized gains (losses) on fixed maturity securities during period, net of income taxes and reclassification adjustments	[1]					(1,714)
Unrealized gains (losses) on derivatives during period, net of income taxes						3
Pension liability adjustment during period, net of income taxes						0
Purchases of treasury stock							(615)
Balance, end of period at Jun. 30, 2018		$ 23,800	$ 135	$ 2,117	$ 30,809	$ 2,852	$ (12,113)

[1] See Note 1 of the Notes to the Consolidated Financial Statements for the adoption of accounting guidance on January 1, 2018.