Share Acitivity within Common, Preferred and Treasury Stock (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Values
Beginning Balance	$ 15,665	$ 14,626	$ 13,764
Shares acquired for treasury	(850)	(654)	(1,320)
Issuance of preferred stock		297	1,034
Issuance of preferred shares		297	1,034
Impact of stock transactions under stock compensation plans, net	75	60	60
Other	(2)		(1)
Ending Balance	15,870	15,665	14,626
4.90% fixed-to-floating non-cumulative Series J perpetual preferred stock
Values
Issuance of preferred shares		297
Series I Preferred Stock
Values
Issuance of preferred shares			441
Preferred stock Series H
Values
Issuance of preferred shares			$ 593
Series G Preferred Stock
Shares
Redemption of preferred shares, Series G			16,442
Common Stock
Values
Beginning Balance	2,051	2,051	$ 2,051
Ending Balance	$ 2,051	$ 2,051	$ 2,051
Shares
Beginning balance	923,892,581	923,892,581	923,892,581
Ending balance	923,892,581	923,892,581	923,892,581
Preferred Stock
Values
Beginning Balance	$ 1,331	$ 1,034	$ 398
Issuance of preferred stock		297	1,034
Redemption of preferred shares, Series G			(398)
Ending Balance	$ 1,331	$ 1,331	$ 1,034
Shares
Beginning balance	54,000	42,000	16,450
Ending balance	54,000	54,000	42,000
Preferred Stock | 4.90% fixed-to-floating non-cumulative Series J perpetual preferred stock
Shares
Issuance of preferred stock		12,000
Preferred Stock | Series I Preferred Stock
Shares
Issuance of preferred stock			18,000
Preferred Stock | Preferred stock Series H
Shares
Issuance of preferred stock			24,000
Preferred Stock | Series G Preferred Stock
Shares
Redemption of preferred shares, Series G			(16,450)
Treasury Stock
Values
Beginning Balance	$ (1,972)	$ (1,295)	$ (634)
Shares acquired for treasury	(847)	(726)	(1,242)
Redemption of preferred shares, Series G			540
Impact of stock transactions under stock compensation plans, net	52	47	38
Other	3	2	3
Ending Balance	$ (2,764)	$ (1,972)	$ (1,295)
Shares
Beginning balance	99,845,629	68,586,836	41,740,524
Shares acquired for treasury	42,607,855	34,799,873	65,516,126
Redemption of preferred shares, Series G			(35,529,018)
Impact of stock transactions under stock compensation plans, net	(3,593,406)	(3,493,671)	(3,697,042)
Other	(47,811)	(47,409)	556,246
Ending balance	138,812,267	99,845,629	68,586,836