Finance Receivables and Loans, Net Finance Receivables and Loans, Net (Consumer Concentration Risk by State and Foreign Geographic) (Details) - Consumer portfolio segment	Dec. 31, 2018	Dec. 31, 2017
Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	100.00%	100.00%
Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	100.00%	100.00%
California and Texas
Concentration Risk [Line Items]
Consumer Concentration Risk	25.40%	24.70%
California | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	8.40%	8.20%
California | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	36.90%	34.60%
Texas | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	12.80%	13.20%
Texas | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	6.20%	6.50%
Florida | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	8.80%	8.50%
Florida | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	4.70%	4.80%
Pennsylvania | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	4.50%	4.60%
Pennsylvania | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	1.40%	1.50%
Illinois | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	4.10%	4.20%
Illinois | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	3.00%	3.20%
Georgia | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	4.10%	4.20%
Georgia | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	2.80%	2.50%
North Carolina | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	3.90%	3.70%
North Carolina | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	1.70%	1.80%
New York | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	3.10%	3.00%
New York | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	2.40%	2.20%
Ohio | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	3.50%	3.40%
Ohio | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	0.40%	0.50%
New Jersey | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	2.70%	2.60%
New Jersey | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	2.10%	2.10%
United States, Other | Automobile loan
Concentration Risk [Line Items]
Consumer Concentration Risk	44.10%	44.40%
United States, Other | Residential mortgage
Concentration Risk [Line Items]
Consumer Concentration Risk	38.40%	40.30%