LHFI by Credit Quality Indicator (Detail) - USD ($) $ in Millions		Jun. 30, 2015	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[1]	$ 132,538	$ 133,112
Financing Receivable, Recorded Investment, Nonaccrual Status	[2],[3]	481	634
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		65,713	65,440
Financing Receivable, Recorded Investment, Nonaccrual Status		140	151
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		6,058	6,741
Financing Receivable, Recorded Investment, Nonaccrual Status		17	21
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		6,058	6,741
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		1,530	1,211
Financing Receivable, Recorded Investment, Nonaccrual Status		1	1
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4],[5]	24,038	23,443
Financing Receivable, Recorded Investment, Nonaccrual Status		147	254
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4]	13,672	14,264
Financing Receivable, Recorded Investment, Nonaccrual Status		153	174
Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4]	401	436
Financing Receivable, Recorded Investment, Nonaccrual Status		18	27
Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6]	5,329	4,573
Financing Receivable, Recorded Investment, Nonaccrual Status		4	6
Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6]	9,834	10,644
Financing Receivable, Recorded Investment, Nonaccrual Status		1	0
Consumer Credit Card Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6]	937	901
Financing Receivable, Recorded Investment, Nonaccrual Status		0	0
Pass | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		64,190	64,228
Pass | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		5,934	6,586
Pass | Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		1,515	1,196
Criticized Accruing | Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		1,383	1,061
Criticized Accruing | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		107	134
Criticized Accruing | Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment		14	14
FICO Score 700 and Above [Member] | Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4]	19,582	18,780
FICO Score 700 and Above [Member] | Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4]	11,076	11,475
FICO Score 700 and Above [Member] | Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4]	324	347
FICO Score 700 and Above [Member] | Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6]	4,754	4,023
FICO Score 700 and Above [Member] | Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6]	7,066	7,661
FICO Score 700 and Above [Member] | Consumer Credit Card Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6]	661	639
FICO Score Between 620 and 699 | Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4]	3,298	3,369
FICO Score Between 620 and 699 | Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4]	1,878	1,991
FICO Score Between 620 and 699 | Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4]	62	70
FICO Score Between 620 and 699 | Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6]	520	476
FICO Score Between 620 and 699 | Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6]	2,181	2,335
FICO Score Between 620 and 699 | Consumer Credit Card Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6]	226	212
FICO Score Below 620 | Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4],[7]	1,158	1,294
FICO Score Below 620 | Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4],[7]	718	798
FICO Score Below 620 | Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[4],[7]	15	19
FICO Score Below 620 | Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6],[7]	55	74
FICO Score Below 620 | Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6],[7]	587	648
FICO Score Below 620 | Consumer Credit Card Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	[6],[7]	$ 50	$ 50

[1] Includes loans of consolidated VIEs of $266 million and $288 million at June 30, 2015 and December 31, 2014, respectively.

[2] Nonaccruing loans past due 90 days or more totaled $273 million. Nonaccruing loans past due fewer than 90 days include modified nonaccrual loans reported as TDRs and performing second lien loans which are classified as nonaccrual when the first lien loan is nonperforming.

[3] Nonaccruing restructured loans are included in total nonaccrual/NPLs.

[4] Excludes $625 million and $632 million of guaranteed residential loans at June 30, 2015 and December 31, 2014, respectively.

[5] Includes $263 million of loans carried at fair value, the majority of which were accruing current.

[6] Excludes $4.4 billion and $4.8 billion of guaranteed student loans at June 30, 2015 and December 31, 2014, respectively.

[7] For substantially all loans with refreshed FICO scores below 620, the borrower’s FICO score at the time of origination exceeded 620 but has since deteriorated as the loan has seasoned.