Common, Preferred and Treasury Stock (Share Acitivity within Common, Preferred and Treasury Stock) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Values
Beginning Balance	$ 15,870	$ 15,665	$ 14,626
Shares acquired for treasury	(661)	(850)	(654)
Issuance of preferred stock			297
Issuance of preferred stock	0	0	297
Impact of stock transactions under stock compensation plans, net	80	75	60
Other	1	(2)	0
Ending Balance	16,232	15,870	15,665	$ 14,626
4.90% fixed-to-floating non-cumulative Series J perpetual preferred stock
Values
Issuance of preferred stock			297
Series I Preferred Stock
Values
Issuance of preferred stock				441
Preferred stock Series H
Values
Issuance of preferred stock				593
Common stock
Values
Beginning Balance	2,051	2,051	2,051
Ending Balance	$ 2,051	$ 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	923,892,581
Preferred Stock
Values
Beginning Balance	$ 1,331	$ 1,331	$ 1,034
Issuance of preferred stock			297
Ending Balance	$ 1,331	$ 1,331	$ 1,331	$ 1,034
Shares
Beginning balance	54,000	54,000	42,000
Ending balance	54,000	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
Treasury Stock
Values
Beginning Balance	$ (2,764)	$ (1,972)	$ (1,295)
Shares acquired for treasury	(668)	(847)	(726)
Impact of stock transactions under stock compensation plans, net	(4)	52	47
Other	3	3	2
Ending Balance	$ (3,433)	$ (2,764)	$ (1,972)	$ (1,295)
Shares
Beginning balance	138,812,267	99,845,629	68,586,836
Shares acquired for treasury	34,633,221	42,607,855	34,799,873
Impact of stock transactions under stock compensation plans, net	42,357	(3,593,406)	(3,493,671)
Other	(74,563)	(47,811)	(47,409)
Ending balance	173,413,282	138,812,267	99,845,629	68,586,836