Business and Summary of Significant Accounting Policies - Credit Quality Indicators (Details)	Dec. 31, 2019	Dec. 31, 2018
FICO Score, Less than 600
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage of loan portfolio per FICO score	6.70%	3.70%
FICO Score, 600 to 699
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage of loan portfolio per FICO score	80.10%	77.90%
FICO Score, Greater than 700
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage of loan portfolio per FICO score	13.20%	18.40%