Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014 CallCentre Branches States ATM Segment	Dec. 31, 2012	Dec. 31, 2013
Accounting Policies [Line Items]
Consolidated total assets of the Company	$ 93,821,000,000		$ 92,934,000,000
Number of retail branches	994
Number of telephone banking call center services group	1
Number of automated teller machines	1,287
Number of States with Automated Teller Machines	12
Number of Business Groups	2
Number of days to designate the loan as nonaccrual for commercial loan payment due period	90 days
Number of days to designate commercial loans will be charged off in full or charged down to the fair value of the underlying collateral payment due period	180 days
Second lien home equity loan with associated first lien due period	120 days or more
Number of days to designate charge-off policy for credit card loans and similar unsecured products taking effect, payment due period	180 days
Number of days to designate the loan as nonaccrual for consumer payment due period	120 days
Number of days to designate the charge-off policy for most consumer loans taking effect, payment due period	120 days
Number of days to designate home equity and residential mortgage loans to get charged down to the fair value of the underlying collateral payment due period	180 days
Maximum level for the impaired loans' outstanding balance leading to a further analysis to determine the probable loss content and assign a specific allowance to the loan	2,500,000
Nonperforming loans, collectively evaluated for impairment	57,066,000,000		54,083,000,000
Liability for credit losses on lending-related commitments	40,000,000		42,000,000
Minimum percentage for an input to be significant of the total fair value of a particular asset or liability	10.00%
Threshold percentage by which amortized cost is greater than fair value to be considered as other-than-temporary	20.00%
Threshold period by which amortized cost is greater than fair value to be considered as other-than-temporary	6 months
Percentage of principal investment	53.00%		57.00%
Fair value of principal investments held in private companies	406,000,000		554,000,000
Fair value at end of year	417,000,000		386,000,000
Accumulated depreciation and amortization on premises and equipment, total	1,300,000,000		1,200,000,000
Internally Developed Software, net of accumulated amortization	64,000,000		60,000,000
Capitalized Computer Software Amortization Maximum Period Allowable	5 years
Vesting period for compensation cost	4 years	3 years
Amortization period of stock-based compensation awards	5 years	4 years
Rate at which employee stock options granted to be exercisable	25.00%
Minimum [Member]
Accounting Policies [Line Items]
Intangible assets useful life	1 year 7 months 6 days
Maximum [Member]
Accounting Policies [Line Items]
Nonperforming loans, collectively evaluated for impairment	2,500,000
Intangible assets useful life	30 years
Options expiration years	10 years
RE Commercial [Member]
Accounting Policies [Line Items]
Fair value at end of year	323,000,000		332,000,000
Allowance for Loans and Leases Receivable [Member]
Accounting Policies [Line Items]
Liability for credit losses on lending-related commitments	$ 36,000,000		$ 37,000,000
Equity Method Investments [Member]
Accounting Policies [Line Items]
Economic interest in unconsolidated investments in voting rights entities, minimum	20.00%
Economic interest in unconsolidated investments in voting rights entities, maximum	50.00%
Cost Method Investments [Member]
Accounting Policies [Line Items]
Economic interest in unconsolidated investments in voting rights entities, Ownership less than	20.00%