Receivables Held for Sale - Additional Information (Detail) - USD ($)		1 Months Ended	3 Months Ended	12 Months Ended
		Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Recorded Investment, Past Due [Line Items]
Receivables held for sale	[1],[2]			$ 5,674,000,000	$ 8,265,000,000
Aggregate unpaid balance				8,577,000,000	11,796,000,000	$ 1,390,000,000
Aggregate carrying value		$ 7,814,000,000		8,429,000,000	12,183,000,000	1,080,000,000
Initial lower of amortized cost or fair value adjustment		$ 541,000,000		587,000,000	234,000,000
Severance and loan review costs			$ 31,000,000
Provision for Credit Losses [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Initial lower of amortized cost or fair value adjustment	[3]			576,000,000	234,000,000	0
Other Revenue [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Initial lower of amortized cost or fair value adjustment	[4]			11,000,000	0	113,000,000
Subsequent to initial transfer to held for sale				201,000,000	130,000,000	(314,000,000)
Fair Value [Member] | Provision for Credit Losses [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Initial lower of amortized cost or fair value adjustment	[3]			576,000,000	234,000,000	0
Fair Value [Member] | Other Revenue [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Initial lower of amortized cost or fair value adjustment	[4]			11,000,000	0	113,000,000
Subsequent to initial transfer to held for sale				$ 263,000,000	$ 155,000,000	$ (457,000,000)

[1] At December 31, 2016, receivables held for sale includes $750 million of closed-end real estate secured receivables which are part of a collateralized funding transaction. These receivables will be sold when they are contractually released as collateral under the public trust and become available for sale. See Note 17, "Variable Interest Entities," for further discussion of our collateralized funding transactions.

[2] The receivable balances included in this table reflect the principal amount outstanding on the loan net of any charge-off recorded in accordance with our existing charge-off policies but exclude any basis adjustments to the loan such as unearned income, unamortized deferred fees and costs on originated loans, purchase accounting fair value adjustments and premiums or discounts on purchased receivables. Additionally, the balances in this table related to receivables which have been classified as held for sale have been reduced by the lower of amortized cost or fair value adjustment recorded as well as the credit loss reserves associated with these receivables prior to the transfer.

[3] Represents the portion of the initial lower of amortized cost or fair value adjustment attributable to credit factors which are recorded as provision for credit losses in the consolidated statement of income (loss).

[4] Represents the portion of the initial lower of amortized cost or fair value adjustment attributable to non-credit factors which are recorded as a component of total other revenues in the consolidated statement income (loss) as it reflects the impact on value caused by current marketplace conditions including changes in interest rates.