Share Acitivity within Common, Preferred and Treasury Stock (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended			1 Months Ended	12 Months Ended			12 Months Ended		1 Months Ended	6 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Jan. 25, 2011 Common Stock	Dec. 31, 2011 Common Stock	Dec. 31, 2013 Common Stock	Dec. 31, 2012 Common Stock	Dec. 31, 2013 Preferred Stock	Dec. 31, 2011 Preferred Stock	Feb. 02, 2011 Preferred Stock Series F Preferred Stock	Jul. 02, 2013 Preferred Stock Series G Preferred Stock	Dec. 31, 2013 Preferred Stock Series G Preferred Stock	Dec. 31, 2013 Preferred Stock Series H Preferred Stock	Dec. 31, 2013 Preferred Stock Preferred stock Series I	Dec. 31, 2013 Treasury Stock	Dec. 31, 2012 Treasury Stock	Dec. 31, 2011 Treasury Stock	Dec. 31, 2013 Treasury Stock Series G Preferred Stock
Values [Abstract]
Beginning balance	$ 13,716			$ 1,779	$ 1,779	$ 2,051	$ 2,051	$ 398	$ 3,654						$ 634	$ 64	$ 130
Issuance of common stock			1,648		272
Redemption of preferred shares, value			3,408						3,408			(398)						(540)
Accretion from dividends on preferred shares, Series F									153	153
Repurchase of treasury shares and related forward contract	(1,320)	(650)													(1,242)	(627)
Issuance of preferred shares	1,034												593	441
Impact of stock transactions under stock compensation plans, net	60	43	44												38	54	65
Other									(1)						(3)	(3)	(1)
Ending Balance	$ 14,589	$ 13,716			$ 2,051	$ 2,051	$ 2,051	$ 1,034	$ 398						$ 1,295	$ 634	$ 64
Shares [Abstract]
Beginning balance				801,504,188	801,504,188	923,892,581	923,892,581	16,450	152,771						41,740,524	4,088,145	5,231,666
Issuance of common stock					122,388,393
Treasury Stock Shares Acquired Cost Method															65,516,126	42,424,014
Issuance of preferred shares													24,000	18,000
Exchange of preferred shares, Series G									(1)
Redemption of preferred shares				121,428,572				(16,450)	(136,320)		16,442				(35,529,018)
Impact of stock transactions under stock compensation plans															(3,697,042)	(4,654,165)	(1,093,116)
Other															556,246	(117,470)	(50,405)
Ending balance					923,892,581	923,892,581	923,892,581	42,000	16,450						68,586,836	41,740,524	4,088,145