Servicing Activities (Schedule Of Total Serviced Automobile Loans Outstanding) (Details) (Automobile Member, USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	$ 115,391	$ 111,589
On-Balance Sheet Loans [Member] | Consumer Loans Auto Financing Receivable [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	58,085	56,417
On-Balance Sheet Loans [Member] | Commercial Automobile [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	34,022	33,803
On-Balance Sheet Loans [Member] | Operating Leases [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	19,510	17,680
On-Balance Sheet Loans [Member] | Operations Held-For-Sale [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	55	54
Off-Balance Sheet Loans [Member] | Securitizations [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	2,832	887
Off-Balance Sheet Loans [Member] | Whole-Loan Transactions [Member]
Automobile Serviced Assets [Line Items]
Total Primary Serviced Assets	$ 887	$ 2,748