Assets and Liabilities Measured at Fair Value on a Recurring Basis (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012		Dec. 31, 2011		Sep. 30, 2011
Assets:
Available For Sale Securities	$ 14,559	[1]	$ 14,520	[1]	$ 15,385	[1]
Trading securities	205		177		189
Residential mortgage loans held for sale	1,741		2,751		1,593
Residential mortgage loans	76	[2]	65	[2]	62	[2]
Derivative assets	2,236		2,356		2,600
Total assets	18,817		19,869		19,829
Liabilities:
Derivative liabilities	1,072		1,344		1,505
Short positions	14		6		8
Total liabilities	1,086		1,350		1,513
US Treasury and Government
Assets:
Available For Sale Securities	41		171		202
US Government Agencies Debt Securities
Assets:
Available For Sale Securities	1,922		1,962		1,990
US States and Political Subdivisions Debt Securities
Assets:
Available For Sale Securities	211		101		105
Trading securities	11		9		12
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Assets:
Available For Sale Securities	8,986		10,284		11,017
Trading securities	14		11		20
Other Debt Securities
Assets:
Available For Sale Securities	3,164		1,812		1,573
Trading securities	13		13		15
Equity Securities, Other
Assets:
Available For Sale Securities	235	[1]	190	[1]	498	[1]
Trading securities	167		144		142
Interest Rate Contract
Assets:
Derivative assets	1,723		1,815		1,914
Liabilities:
Derivative liabilities	757		858		923
Foreign Exchange Contract
Assets:
Derivative assets	216		294		471
Liabilities:
Derivative liabilities	198		275		447
Equity Contract
Assets:
Derivative assets	198		113		103
Liabilities:
Derivative liabilities	22		81		30
Commodity Contract
Assets:
Derivative assets	99		134		112
Liabilities:
Derivative liabilities	95		130		105
Fair Value, Inputs, Level 1
Assets:
Available For Sale Securities	120	[1]	356	[1]	693	[1]
Trading securities	167		144		142
Derivative assets	8		8		3
Total assets	295		508		838
Liabilities:
Derivative liabilities	92		54		59
Short positions	11		2		7
Total liabilities	103		56		66
Fair Value, Inputs, Level 1 | US Treasury and Government
Assets:
Available For Sale Securities	41		171		202
Fair Value, Inputs, Level 1 | Equity Securities, Other
Assets:
Available For Sale Securities	79	[1]	185	[1]	491	[1]
Trading securities	167		144		142
Fair Value, Inputs, Level 1 | Interest Rate Contract
Assets:
Derivative assets	8		8		3
Liabilities:
Derivative liabilities	92		54		59
Fair Value, Inputs, Level 2
Assets:
Available For Sale Securities	14,439		14,164		14,692
Trading securities	37		32		46
Residential mortgage loans held for sale	1,741		2,751		1,593
Derivative assets	1,928		2,201		2,455
Total assets	18,145		19,148		18,786
Liabilities:
Derivative liabilities	955		1,207		1,414
Short positions	3		4		1
Total liabilities	958		1,211		1,415
Fair Value, Inputs, Level 2 | US Government Agencies Debt Securities
Assets:
Available For Sale Securities	1,922		1,962		1,990
Fair Value, Inputs, Level 2 | US States and Political Subdivisions Debt Securities
Assets:
Available For Sale Securities	211		101		105
Trading securities	10		8		11
Fair Value, Inputs, Level 2 | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Assets:
Available For Sale Securities	8,986		10,284		11,017
Trading securities	14		11		20
Fair Value, Inputs, Level 2 | Other Debt Securities
Assets:
Available For Sale Securities	3,164		1,812		1,573
Trading securities	13		13		15
Fair Value, Inputs, Level 2 | Equity Securities, Other
Assets:
Available For Sale Securities	156		5		7
Fair Value, Inputs, Level 2 | Interest Rate Contract
Assets:
Derivative assets	1,613		1,773		1,872
Liabilities:
Derivative liabilities	662		802		862
Fair Value, Inputs, Level 2 | Foreign Exchange Contract
Assets:
Derivative assets	216		294		471
Liabilities:
Derivative liabilities	198		275		447
Fair Value, Inputs, Level 2 | Commodity Contract
Assets:
Derivative assets	99		134		112
Liabilities:
Derivative liabilities	95		130		105
Fair Value, Inputs, Level 3
Assets:
Trading securities	1		1		1
Residential mortgage loans	76	[2]	65	[2]	62	[2]
Derivative assets	300		147		142
Total assets	377		213		205
Liabilities:
Derivative liabilities	25		83		32
Total liabilities	25		83		32
Fair Value, Inputs, Level 3 | US States and Political Subdivisions Debt Securities
Assets:
Trading securities	1		1		1
Fair Value, Inputs, Level 3 | Interest Rate Contract
Assets:
Derivative assets	102		34		39
Liabilities:
Derivative liabilities	3		2		2
Fair Value, Inputs, Level 3 | Equity Contract
Assets:
Derivative assets	198		113		103
Liabilities:
Derivative liabilities	$ 22		$ 81		$ 30

[1] Excludes FHLB and FRB restricted stock totaling $497 and $346, respectively, at September 30, 2012 and $497 and $345, respectively, at December 31, 2011 and September 30, 2011.

[2] Includes residential mortgage loans originated as held for sale and subsequently transferred to held for investment. During the three and nine months ended September 30, 2012, no assets or liabilities were transferred between Level 1 and Level 2