Purchased Receivables - Summary Of Components Of Net Purchased Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Purchased Receivables [Abstract]
Purchased receivables	$ 22,431	$ 20,662
Reserve for purchased receivable losses	(200)	(171)	$ (181)	$ (289)
Total	$ 22,231	$ 20,491