Credit Loss Reserves - Summarizes Changes in Credit Loss Reserves by Product/Class and Related Receivable Balance by Product - Additional Information (Detail) - USD ($) $ in Millions		1 Months Ended	3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Initial lower of amortized cost or fair value adjustment		$ 541	$ 562	$ 12	$ 587	$ 232
Out of period adjustment to net charge-offs					(12)
Write-offs	[1],[2]		827	90	938	2,135
Excludes Credit loss reserves for TDR Loans that are carried at the lower of amortized cost or fair value				10		10
TDR [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Excludes TDR loans that are carried at the lower of amortized cost or fair value				249		249
Real Estate Secured Receivable Portfolio [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Write-offs			244	24	268	1,617
Mortgage Receivable [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Release of provision associated with a correction to the reserve calculation for a segment of the portfolio					19
Provision for Credit Losses [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Initial lower of amortized cost or fair value adjustment	[3]		$ 557	$ 12	$ 576	$ 232

[1] For collateral dependent receivables that are transferred to held for sale, existing credit loss reserves at the time of transfer are recognized as a charge-off. We transferred to held for sale certain real estate secured receivables during the three and nine months ended September 30, 2016 and 2015 and, accordingly, we recognized the existing credit loss reserves on these receivables as additional charge-off totaling $244 million and $268 million during the three and nine months ended September 30, 2016, compared with $24 million and $1,617 million during the three and nine months ended September 30, 2015, respectively.

[2] The provision for credit losses and charge-offs for real estate secured receivables during the three and nine months ended September 30, 2016 include $557 million and $576 million, respectively, related to the lower of amortized cost or fair value adjustment attributable to credit factors for receivables transferred to held for sale. For the three and nine months ended September 30, 2015, the provision for credit losses and charge-offs included $12 million and $232 million, respectively, related to the lower of amortized cost or fair value adjustment attributable to credit factors for receivables transferred to held for sale. See Note 4, "Receivables Held for Sale," for additional information. During the nine months ended September 30, 2016, net charge-offs dollars were impacted by an out of period adjustment which decreased net charge-offs by $12 million in order to properly reflect charge-offs for receivables which received a partial forgiveness of principal as a result of an account modification in prior periods. The provision for credit losses for real estate secured receivables during the nine months ended September 30, 2015 was impacted by a release of approximately $19 million associated with a correction to our credit loss reserve calculation for a segment of our portfolio.

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