Finance Receivables - Finance Receivables, net (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Finance receivables, net	$ 34,385	$ 33,000
North America Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Finance receivables, net	18,356	15,943
International Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Finance receivables, net	16,029	17,057
Consumer Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment, net of fees	25,931	24,389
Individually evaluated for impairment, net of fees	1,399	1,234
Total finance receivables	27,330	25,623
Less: allowance for loan losses - collective	(518)	(483)
Less: allowance for loan losses - specific	(203)	(172)
Total finance receivables, net	26,609	24,968
Consumer Finance Receivables [Member] | North America Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment, net of fees	14,091	12,127
Individually evaluated for impairment, net of fees	1,399	1,234
Total finance receivables	15,490	13,361
Less: allowance for loan losses - collective	(424)	(405)
Less: allowance for loan losses - specific	(203)	(172)
Total finance receivables, net	14,863	12,784
Consumer Finance Receivables [Member] | North America Segment [Member] | Post-Acquisition Portfolio [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and Leases Receivable, Deferred Income	164	245
Consumer Finance Receivables [Member] | International Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment, net of fees	11,840	12,262
Individually evaluated for impairment, net of fees	0	0
Total finance receivables	11,840	12,262
Less: allowance for loan losses - collective	(94)	(78)
Less: allowance for loan losses - specific	0	0
Total finance receivables, net	11,746	12,184
Loans and Leases Receivable, Gross, Consumer, Lease Financing	1,100	1,000
Commercial Finance Receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment, net of fees	7,758	7,983
Individually evaluated for impairment, net of fees	57	89
Total finance receivables	7,815	8,072	$ 7,114	$ 6,700
Less: allowance for loan losses - collective	(34)	(35)
Less: allowance for loan losses - specific	(5)	(5)
Total finance receivables, net	7,776	8,032
Commercial Finance Receivables [Member] | North America Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment, net of fees	3,515	3,180
Individually evaluated for impairment, net of fees	0	0
Total finance receivables	3,515	3,180	2,373	1,975
Less: allowance for loan losses - collective	(22)	(21)
Less: allowance for loan losses - specific	0	0
Total finance receivables, net	3,493	3,159
Commercial Finance Receivables [Member] | International Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Collectively evaluated for impairment, net of fees	4,243	4,803
Individually evaluated for impairment, net of fees	57	89
Total finance receivables	4,300	4,892	$ 4,741	$ 4,725
Less: allowance for loan losses - collective	(12)	(14)
Less: allowance for loan losses - specific	(5)	(5)
Total finance receivables, net	$ 4,283	$ 4,873