Finance Receivables and Loans, Net Finance Receivables and Loans, Net (Commercial Criticized Exposure) (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Commercial Criticized Finance Receivables and Loans	$ 1.000	$ 1.000
5500 Retail, Auto Dealers and Gasoline Stations [Member]
Concentration Risk [Line Items]
Commercial Criticized Finance Receivables and Loans	0.763	0.812
7380 Services, Miscellaneous Business Services [Member]
Concentration Risk [Line Items]
Commercial Criticized Finance Receivables and Loans	0.067	0.063
8071 Services, Medical Laboratories [Member]
Concentration Risk [Line Items]
Commercial Criticized Finance Receivables and Loans	0.049	0.023
810000 to 819999 Other Services (except Public Administration) [Member]
Concentration Risk [Line Items]
Commercial Criticized Finance Receivables and Loans	$ 0.121	$ 0.102