Receivables, net - TDR Loans (Detail) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Financing Receivable, Modifications [Line Items]
Unpaid principal balance subject to reduction		$ 740	$ 549
TDR Loans held for investment, recorded at the lower of amortized cost or FV less cost to sell		250	517
First lien [Member]
Financing Receivable, Modifications [Line Items]
Carrying value of TDR Loans	[1],[2]	870	9,630
Unpaid balance of TDR loans	[1],[2]	1,003	9,931
Credit loss reserves for TDR loans	[3]	95	1,738
Second lien [Member]
Financing Receivable, Modifications [Line Items]
Carrying value of TDR Loans	[1],[2]	652	915
Unpaid balance of TDR loans	[1],[2]	732	1,050
Credit loss reserves for TDR loans	[3]	135	244
Receivables Held For Sale [Member] | Real Estate Secured [Member]
Financing Receivable, Modifications [Line Items]
Carrying value of TDR Loans	[2],[4]	6,044	650
Unpaid balance of TDR loans	[2],[4]	7,317	1,004
Real estate secured [Member]
Financing Receivable, Modifications [Line Items]
Carrying value of TDR Loans	[2]	7,566	11,195
Unpaid balance of TDR loans	[2]	9,052	11,985
Credit loss reserves for TDR loans	[3],[4]	$ 230	$ 1,982

[1] At December 31, 2015 and December 31, 2014, the carrying value of TDR Loans held for investment totaling $250 million and $517 million, respectively, are recorded at the lower of amortized cost or fair value of the collateral less cost to sell.

[2] At December 31, 2015 and December 31, 2014, the unpaid principal balance reflected above includes $740 million and $549 million, respectively, which have received a reduction in the unpaid principal balance as part of an account management action.

[3] Included in credit loss reserves.

[4] There are no credit loss reserves associated with receivables classified as held for sale as they are carried at the lower of amortized cost or fair value.