Servicing Activities (Schedule Of Total Serviced Automobile Loans Outstanding) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Automobile Serviced Assets [Line Items]
Servicing fees	$ 13	$ 10
Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Servicing fees	13	$ 10
Total Primary Serviced Assets	118,581		$ 119,808
Consumer Loan [Member] | On-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	62,819		64,067
Commercial Loan [Member] | On-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	34,325		34,895
Operating Leases [Member] | On-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	14,690		15,965
Other Assets [Member] | On-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	67		72
Securitizations [Member] | Off-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	3,168		2,550
Whole-Loan Transactions [Member] | Off-Balance Sheet Loans [Member] | Automobile Loan [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	$ 3,512		$ 2,259