Loans Receivable - Aging of the Loans Receivable Balance (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans receivable	13.50%	14.60%
Current loans receivable	86.50%	85.40%
Balance of Credit Card Loans on Nonaccrual Status	$ 1,954	$ 2,110
30-59 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans receivable	6.30%	6.90%
60-89 days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans receivable	3.10%	3.40%
90 or more days past due
Financing Receivable, Recorded Investment, Past Due [Line Items]
Past due loans receivable	4.10%	4.30%
Balance of Loans Receivable 90 or More Days Past Due and Still Accruing Interest and Fees	$ 0	$ 0