Finance Receivables - Allowance for Loan Losses (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	$ 27
Provision for loan losses	604	475
Balance at end of period	31	27
Post-Acquisition Portfolio [Member] | Consumer Finance Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	497	345
Provision for loan losses	613	432
Charge-offs	(914)	(638)
Recoveries	470	356
Foreign currency translation	(11)	2
Balance at end of period	655	497
Post-Acquisition Portfolio [Member] | North America Segment [Member] | Consumer Finance Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	468	345	179
Provision for loan losses	468	380	298
Charge-offs	(776)	(584)	(304)
Recoveries	417	327	172
Foreign currency translation	0	0	0
Balance at end of period	577	468	345
Post-Acquisition Portfolio [Member] | International Segment [Member] | Consumer Finance Receivables [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance at beginning of period	29	0
Provision for loan losses	145	52
Charge-offs	(138)	(54)
Recoveries	53	29
Foreign currency translation	(11)	2
Balance at end of period	$ 78	$ 29