Loan Receivables and Allowance for Loan Losses - Credit Quality Indicators (Details)	Dec. 31, 2016	Dec. 31, 2015
661 or higher | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of class of loan receivable	72.60%	73.00%
661 or higher | Consumer installment loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of class of loan receivable	77.90%	77.70%
661 or higher | Commercial credit products
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of class of loan receivable	87.10%	86.80%
601 to 660 | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of class of loan receivable	19.70%	19.80%
601 to 660 | Consumer installment loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of class of loan receivable	16.30%	16.60%
601 to 660 | Commercial credit products
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of class of loan receivable	8.50%	8.70%
600 or less | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of class of loan receivable	7.70%	7.20%
600 or less | Consumer installment loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of class of loan receivable	5.80%	5.70%
600 or less | Commercial credit products
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of class of loan receivable	4.40%	4.50%