Loans and Finance Receivables Held for Investment and Allowance for Credit Losses (Narrative) (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Apr. 01, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and finance receivables	$ 1,227,811,000		$ 1,227,811,000			$ 1,169,407,000
Originations of loans held for investment, modified			0	$ 801,000
Proceeds from sale of previously charged-off loans	0	$ 200,000	0	900,000
Allowance for loan losses for non-delinquent loans	71,300,000		71,300,000			85,700,000
Allowance for loan losses for delinquent loans	76,700,000		76,700,000			54,300,000
Unused lines of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Off-balance sheet credit exposure	290,300,000		290,300,000			264,200,000
Reserve for Off-balance Sheet Activities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Related accrual for unfunded loan commitments	6,200,000		6,200,000			$ 5,900,000
Financial Institutions Borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originations of loans held for investment, modified	$ 102,400,000	$ 112,100,000	$ 309,500,000	$ 360,600,000
On Deck Capital Canada
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and finance receivables					$ 36,800,000