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		105
Compensation amortization under share-based plans and other changes		151
Net income	$ 2,573		2,573
Dividends			(561)
Other comprehensive income (loss)	(848)			(848)
Treasury stock acquired - share repurchase authorization					(2,150)
Net shares acquired related to employee share-based compensation plans					(73)
Shareholders' equity, end of period at Sep. 30, 2015	24,033	22,099	29,263	32	(27,361)
Balance, beginning of year at Dec. 31, 2014						322.2
Common shares outstanding
Treasury stock acquired - share repurchase authorization						(20.8)
Net shares issued under employee share-based compensation plans						2.8
Balance, end of period at Sep. 30, 2015						304.2
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		123
Compensation amortization under share-based plans and other changes		124
Net income	2,071		2,071
Dividends			(571)
Other			(2)
Other comprehensive income (loss)	817			817
Treasury stock acquired - share repurchase authorization	(1,650)				(1,650)
Net shares acquired related to employee share-based compensation plans	(71)				(71)
Shareholders' equity, end of period at Sep. 30, 2016	$ 24,439	$ 22,419	$ 31,443	$ 660	$ (30,083)
Balance, beginning of year at Dec. 31, 2015	295.9					295.9
Common shares outstanding
Treasury stock acquired - share repurchase authorization	(14.7)					(14.7)
Net shares issued under employee share-based compensation plans						2.9
Balance, end of period at Sep. 30, 2016	284.1					284.1