Fair Value Measurements - Assets and Liabilities Recorded as Fair Value on Nonrecurring Basis (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended										3 Months Ended				9 Months Ended																				3 Months Ended				9 Months Ended																				3 Months Ended				9 Months Ended																				3 Months Ended				9 Months Ended																				3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014 Level 1 [Member]	Dec. 31, 2013 Level 1 [Member]	Sep. 30, 2014 Level 2 [Member]	Dec. 31, 2013 Level 2 [Member]	Sep. 30, 2014 Level 3 [Member]	Dec. 31, 2013 Level 3 [Member]	Sep. 30, 2014 Estimate of Fair Value Measurement [Member]	Dec. 31, 2013 Estimate of Fair Value Measurement [Member]	Sep. 30, 2014 Residential Mortgage [Member]		Sep. 30, 2013 Residential Mortgage [Member]		Sep. 30, 2014 Residential Mortgage [Member]		Sep. 30, 2013 Residential Mortgage [Member]		Sep. 30, 2014 Residential Mortgage [Member] Level 1 [Member]		Dec. 31, 2013 Residential Mortgage [Member] Level 1 [Member]		Sep. 30, 2014 Residential Mortgage [Member] Level 2 [Member]		Dec. 31, 2013 Residential Mortgage [Member] Level 2 [Member]		Sep. 30, 2014 Residential Mortgage [Member] Level 3 [Member]		Dec. 31, 2013 Residential Mortgage [Member] Level 3 [Member]		Sep. 30, 2014 Residential Mortgage [Member] Estimate of Fair Value Measurement [Member]		Dec. 31, 2013 Residential Mortgage [Member] Estimate of Fair Value Measurement [Member]		Sep. 30, 2014 Impaired commercial loans [Member]		Sep. 30, 2013 Impaired commercial loans [Member]		Sep. 30, 2014 Impaired commercial loans [Member]		Sep. 30, 2013 Impaired commercial loans [Member]		Sep. 30, 2014 Impaired commercial loans [Member] Level 1 [Member]		Dec. 31, 2013 Impaired commercial loans [Member] Level 1 [Member]		Sep. 30, 2014 Impaired commercial loans [Member] Level 2 [Member]		Dec. 31, 2013 Impaired commercial loans [Member] Level 2 [Member]		Sep. 30, 2014 Impaired commercial loans [Member] Level 3 [Member]		Dec. 31, 2013 Impaired commercial loans [Member] Level 3 [Member]		Sep. 30, 2014 Impaired commercial loans [Member] Estimate of Fair Value Measurement [Member]		Dec. 31, 2013 Impaired commercial loans [Member] Estimate of Fair Value Measurement [Member]		Sep. 30, 2014 Impaired Consumer Loans [Member]		Sep. 30, 2013 Impaired Consumer Loans [Member]		Sep. 30, 2014 Impaired Consumer Loans [Member]		Sep. 30, 2013 Impaired Consumer Loans [Member]		Sep. 30, 2014 Impaired Consumer Loans [Member] Level 1 [Member]		Dec. 31, 2013 Impaired Consumer Loans [Member] Level 1 [Member]		Sep. 30, 2014 Impaired Consumer Loans [Member] Level 2 [Member]		Dec. 31, 2013 Impaired Consumer Loans [Member] Level 2 [Member]		Sep. 30, 2014 Impaired Consumer Loans [Member] Level 3 [Member]		Dec. 31, 2013 Impaired Consumer Loans [Member] Level 3 [Member]		Sep. 30, 2014 Impaired Consumer Loans [Member] Estimate of Fair Value Measurement [Member]		Dec. 31, 2013 Impaired Consumer Loans [Member] Estimate of Fair Value Measurement [Member]		Sep. 30, 2014 Real Estate Owned [Member]		Sep. 30, 2013 Real Estate Owned [Member]		Sep. 30, 2014 Real Estate Owned [Member]		Sep. 30, 2013 Real Estate Owned [Member]		Sep. 30, 2014 Real Estate Owned [Member] Level 1 [Member]		Dec. 31, 2013 Real Estate Owned [Member] Level 1 [Member]		Sep. 30, 2014 Real Estate Owned [Member] Level 2 [Member]		Dec. 31, 2013 Real Estate Owned [Member] Level 2 [Member]		Sep. 30, 2014 Real Estate Owned [Member] Level 3 [Member]		Dec. 31, 2013 Real Estate Owned [Member] Level 3 [Member]		Sep. 30, 2014 Real Estate Owned [Member] Estimate of Fair Value Measurement [Member]		Dec. 31, 2013 Real Estate Owned [Member] Estimate of Fair Value Measurement [Member]		Sep. 30, 2014 Commercial Loans Held for Sale [Member]	Sep. 30, 2014 Commercial Loans Held for Sale [Member]		Sep. 30, 2014 Commercial Loans Held for Sale [Member] Level 1 [Member]		Sep. 30, 2014 Commercial Loans Held for Sale [Member] Level 2 [Member]		Sep. 30, 2014 Commercial Loans Held for Sale [Member] Level 3 [Member]		Sep. 30, 2014 Commercial Loans Held for Sale [Member] Estimate of Fair Value Measurement [Member]
Fair Value, Assets and Liabilities Measured on a Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Nonrecurring					$ 0	$ 0	$ 241	$ 521	$ 40	$ 164	$ 281	$ 685									$ 0	[1]	$ 0	[1]	$ 3	[1]	$ 9	[1]	$ 21	[1]	$ 56	[1]	$ 24	[1]	$ 65	[1]									$ 0	[2]	$ 0	[2]	$ 0	[2]	$ 0	[2]	$ 19	[2]	$ 108	[2]	$ 19	[2]	$ 108	[2]									$ 0	[3]	$ 0	[3]	$ 139	[3]	$ 492	[3]	$ 0	[3]	$ 0	[3]	$ 139	[3]	$ 492	[3]									$ 0	[4]	$ 0	[4]	$ 19	[4]	$ 20	[4]	$ 0	[4]	$ 0	[4]	$ 19	[4]	$ 20	[4]				$ 0	[5]	$ 80	[5]	$ 0	[5]	$ 80	[5]
Total Gains (Losses)	$ (6)	$ (18)	$ (31)	$ (59)									$ (1)	[1]	$ (14)	[1]	$ (1)	[1]	$ (4)	[1]																	$ 3	[2]	$ 19	[2]	$ 6	[2]	$ 17	[2]																	$ (10)	[3]	$ (21)	[3]	$ (33)	[3]	$ (72)	[3]																	$ 2	[4]	$ (2)	[4]	$ 4	[4]	$ 0	[4]																	$ 0	$ (7)	[5]

[1] As of September 30, 2014 and December 31, 2013, the fair value of the loans held for sale was below cost. Certain residential mortgage loans held for sale have been classified as a Level 3 fair value measurement within the fair value hierarchy as the underlying real estate properties which determine fair value are illiquid assets as a result of market conditions and significant inputs in estimating fair value were unobservable. Additionally, the fair value of these properties is affected by, among other things, the location, the payment history and the completeness of the loan documentation.

[2] Certain commercial loans have undergone troubled debt restructurings and are considered impaired. As a matter of practical expedient, we measure the credit impairment of a collateral-dependent loan based on the fair value of the collateral asset. The collateral often involves real estate properties that are illiquid due to market conditions. As a result, these loans are classified as a Level 3 fair value measurement within the fair value hierarchy.

[3] Represents residential mortgage loans held for investment whose carrying amount was reduced during the periods presented based on the fair value of the underlying collateral.

[4] Real estate owned is required to be reported on the balance sheet net of transactions costs. The real estate owned amounts in the table above reflect the fair value unadjusted for transaction costs.

[5] As of September 30, 2014, the fair value of the loans held for sale was below cost.