Credit Loss Reserves - Summarizes Changes in Credit Loss Reserves by Product/Class and Related Receivable Balance by Product - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Financing Receivable, Allowance for Credit Losses [Line Items]
Initial lower of amortized cost or fair value adjustment		$ 8		$ 25	$ 220
Out of period adjustment to net charge-offs		(12)		(12)
Write-offs	[1],[2]	32	$ 1,898	111	2,045
Excludes Credit loss reserves for TDR Loans that are carried at the lower of amortized cost or fair value		9	10	9	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		213	256	213	256
Real Estate Secured Receivable Portfolio [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Write-offs		4	1,578	24	1,593
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
First and Second Mortgage [Member] | Fair Value [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Initial lower of amortized cost or fair value adjustment		$ 6	$ 220	$ 19	$ 220

[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 six months ended June 30, 2016 and 2015 and, accordingly, we recognized the existing credit loss reserves on these receivables as additional charge-off totaling $4 million and $24 million during the three and six months ended June 30, 2016, compared with $1,578 million and $1,593 million during the three and six months ended June 30, 2015, respectively.

[2] The provision for credit losses and charge-offs for real estate secured receivables during the three and six months ended June 30, 2016 include $6 million and $19 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 six months ended June 30, 2015, the provision for credit losses and charge-offs included $220 million and $220 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 three and six months ended June 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 six months ended June 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.