Purchased Receivables - Narrative (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) segment purchased_receivable	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($) purchased_receivable
Purchased Receivables [Abstract]
Term of purchased receivables (less than)	1 year
Number of classes of purchased receivables | segment	1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Restructured purchased receivables	$ 25,528,000		$ 23,800,000
Charge-offs	$ 1,104,000	$ 279,000
Purchased Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of purchased receivables past due | purchased_receivable	0		0
Restructured purchased receivables	$ 0		$ 0
Charge-offs	$ 0	$ 0