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, 2014		$ 21,843	$ 27,251	$ 880	$ (25,138)
Shareholders' Equity [Rollforward]
Employee share-based compensation		87
Compensation amortization under share-based plans and other changes		109
Net income	$ 1,645		1,645
Dividends			(372)
Other comprehensive income (loss)	(711)			(711)
Treasury stock acquired - share repurchase authorization					(1,400)
Net shares acquired related to employee share-based compensation plans					(73)
Shareholders' equity, end of period at Jun. 30, 2015	24,121	22,039	28,524	169	(26,611)
Balance, beginning of year at Dec. 31, 2014						322.2
Common shares outstanding
Treasury stock acquired - share repurchase authorization						(13.5)
Net shares issued under employee share-based compensation plans						2.5
Balance, end of period at Jun. 30, 2015						311.2
Shareholders' equity, beginning of year at Dec. 31, 2015	23,598	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 (loss)	1,122			1,122
Treasury stock acquired - share repurchase authorization	(1,100)				(1,100)
Net shares acquired related to employee share-based compensation plans	(59)				(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					295.9
Common shares outstanding
Treasury stock acquired - share repurchase authorization	(10.0)					(10.0)
Net shares issued under employee share-based compensation plans						2.4
Balance, end of period at Jun. 30, 2016	288.3					288.3