Goodwill and Other Intangible Assets - Changes in the Carrying Amounts of Other Intangible Assets (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015		Jun. 30, 2014		Dec. 31, 2014	Dec. 31, 2013
Amortization of Intangible Assets and Impairment of Goodwill		$ 7	$ 4	$ 13		$ 7
Servicing Asset at Fair Value, Amount		1,393		1,393				$ 1,206
Amortization	[1]			(3)		(7)
Origination of Mortgage Servicing Rights (MSRs)				130		68
Servicing Assets at Fair Value, Purchased				109		76
Due to changes in inputs or assumptions	[2]			72		(107)
Servicing Asset at Fair Value, Other Changes in Fair Value	[3]			(109)		(78)
Servicing Asset at Fair Value, Disposals				(2)
Intangible Assets, Written off Related to Sale of Business Unit						(9)
Ending Balance		1,416	1,277	1,416		1,277
Mortgage Servicing Rights, Fair Value [Member]
Servicing Asset at Fair Value, Amount		1,393	1,259	1,393		1,259		$ 1,206	$ 1,300
Amortization				0		0
Origination of Mortgage Servicing Rights (MSRs)				117		68
Servicing Assets at Fair Value, Purchased				109		76
Due to changes in inputs or assumptions				72	[1]	(107)	[2]
Servicing Asset at Fair Value, Other Changes in Fair Value	[3]			(109)		(78)
Servicing Asset at Fair Value, Disposals				(2)
Intangible Assets, Written off Related to Sale of Business Unit						0
Other Intangible Assets [Member]
Amortization	[1]			(3)		(7)
Origination of Mortgage Servicing Rights (MSRs)				13		0
Servicing Assets at Fair Value, Purchased				0		0
Due to changes in inputs or assumptions				0		0
Servicing Asset at Fair Value, Other Changes in Fair Value				0		0
Servicing Asset at Fair Value, Disposals				0
Intangible Assets, Written off Related to Sale of Business Unit						(9)
Ending Balance		23	18	23		18
Community Development Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member]
Amortization of Intangible Assets and Impairment of Goodwill		$ 5	$ 3	$ 10		$ 5

[1] Does not include amortization of tax credits for non-qualified community development investments, which totaled $10 million reflected in amortization on the Company's Consolidated Statements of Income and $5 million reflected in other noninterest expense on the Company's Consolidated Statements of Income for the six months ended June 30, 2015 and 2014, respectively. See Note 8, "Certain Transfers of Financial Assets and Variable Interest Entities," for additional information.

[2] Primarily reflects changes in option adjusted spreads and prepayment speed assumptions, due to changes in interest rates.

[3] Represents changes due to the collection of expected cash flows, net of accretion, due to the passage of time.