Receivables - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Accounts, Notes, Loans and Financing Receivable [Line Items]
Aggregate carrying value	$ 11,399	$ 11,504	$ 332	$ 11,815	$ 674
Deferred origination fees	63	63		63		$ 159
Net unamortized premium on our receivables	45	45		45		76
Secured financing	1,012	1,012		1,012		1,489
Receivables, collateralizing long-term debt	$ 1,915	$ 1,915		$ 1,915		$ 2,999