Consolidated Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common stock [Member]	Retained earnings [Member]	Accumulated other comprehensive income (loss), net of tax [Member]	Treasury stock, at cost [Member]	Common shares outstanding [Member]
Shareholders' equity, beginning of year at Dec. 31, 2015		$ 22,172	$ 29,945	$ (157)	$ (28,362)
Shareholders' Equity [Rollforward]
Employee share-based compensation		95
Compensation amortization under share-based plans and other changes		82
Net income	$ 1,355		1,355
Dividends			(378)
Other			(1)
Other comprehensive income	1,122			1,122
Treasury stock acquired - share repurchase authorization					(1,100)
Net shares acquired related to employee share-based compensation plans					(59)
Shareholders' equity, end of period at Jun. 30, 2016	24,714	22,349	30,921	965	(29,521)
Balance, beginning of year at Dec. 31, 2015						295.9
Common shares outstanding
Treasury stock acquired - share repurchase authorization						(10.0)
Net shares issued under employee share-based compensation plans						2.4
Balance, end of period at Jun. 30, 2016						288.3
Shareholders' equity, beginning of year at Dec. 31, 2016	23,221	22,614	32,196	(755)	(30,834)
Shareholders' Equity [Rollforward]
Employee share-based compensation		94
Compensation amortization under share-based plans and other changes		73
Net income	1,212		1,212
Dividends			(391)
Other			(1)
Other comprehensive income	411			411
Treasury stock acquired - share repurchase authorization	(700)				(700)
Net shares acquired related to employee share-based compensation plans	(61)				(61)
Shareholders' equity, end of period at Jun. 30, 2017	$ 23,858	$ 22,781	$ 33,016	$ (344)	$ (31,595)
Balance, beginning of year at Dec. 31, 2016	279.6					279.6
Common shares outstanding
Treasury stock acquired - share repurchase authorization	(5.7)					(5.7)
Net shares issued under employee share-based compensation plans						2.0
Balance, end of period at Jun. 30, 2017	275.9					275.9