Composition of the Company's Loan Portfolio (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 133,112	[1]	$ 127,877	[1]
Loans Held for Sale	3,232	[2],[3]	1,699	[2]
Commercial Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	73,392		64,310
Residential Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	38,775		43,190
Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	20,945		20,377
Commercial and Industrial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	65,440		57,974
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	6,741		5,481
Commercial Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	1,211		855
Residential Guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	632		3,416
Residential Nonguaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	23,443	[4],[5],[6]	24,412	[4],[5],[7]
Home Equity Line of Credit [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	14,264	[4]	14,809	[4]
Residential Construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	436	[4]	553	[4]
Federally Guaranteed Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	4,827		5,545
Consumer Other Direct [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	4,573	[8]	2,829	[8]
Consumer Indirect [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	10,644	[8]	11,272	[8]
Consumer Credit Card Financing Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	901	[8]	731	[8]
Loans Held For Investment [Member] | Federally Guaranteed Student Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans held for investment	$ 4,827

[1] Includes noncontrolling interest of $108 million and $119 million at December 31, 2014 and December 31, 2013, respectively.

[2] Includes debt of consolidated VIEs of $302 million and $597 million at December 31, 2014 and December 31, 2013, respectively, of which $0 million and $256 million are carried at fair value at December 31, 2014 and December 31, 2013, respectively.

[3] Includes $1.9 billion and $1.4 billion of LHFS carried at fair value at December 31, 2014 and 2013, respectively.

[4] Excludes $632 million and $3.4 billion of guaranteed residential loans at December 31, 2014 and 2013, respectively.

[5] Includes $272 million and $302 million of LHFI carried at fair value at December 31, 2014 and 2013, respectively.

[6] Includes $272 million of loans carried at fair value, the majority of which were accruing current.

[7] Includes $302 million of loans carried at fair value, the majority of which were accruing current.

[8] Excludes $4.8 billion and $5.5 billion of guaranteed student loans at December 31, 2014 and 2013, respectively.