Loans and Finance Receivables Held for Investment and Allowance for Credit Losses (Narrative) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Apr. 01, 2019	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and finance receivables	$ 1,207,609,000		$ 1,207,609,000			$ 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		700,000
Allowance for loan losses for non-delinquent loans	70,500,000		70,500,000			85,700,000
Allowance for loan losses for delinquent loans	75,300,000		75,300,000			54,300,000
Unused lines of Credit
Accounts, Notes, Loans and Financing Receivable [Line Items]
Off-balance sheet credit exposure	282,200,000		282,200,000			264,200,000
Reserve for Off-balance Sheet Activities
Accounts, Notes, Loans and Financing Receivable [Line Items]
Related accrual for unfunded loan commitments	6,300,000		6,300,000			$ 5,900,000
Financial Institutions Borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Originations of loans held for investment, modified	$ 95,500,000	$ 109,300,000	$ 207,100,000	$ 248,500,000
On Deck Capital Canada
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans and finance receivables					$ 37,500,000