Revenue from Contracts with Customers - Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Disaggregation of Revenue [Line Items]
Service fee and commission income	$ 11,772	$ 8,860	$ 21,587	$ 18,511
Extended Warranty | IWS | Vehicle service agreement fees
Disaggregation of Revenue [Line Items]
Service fee and commission income	4,551	4,226	9,030	8,615
Extended Warranty | IWS | GAP commissions
Disaggregation of Revenue [Line Items]
Service fee and commission income	226	200	484	392
Extended Warranty | Trinity | Maintenance support service fees
Disaggregation of Revenue [Line Items]
Service fee and commission income	1,732	1,962	3,700	4,935
Extended Warranty | Trinity | Warranty product commissions
Disaggregation of Revenue [Line Items]
Service fee and commission income	817	736	1,399	1,232
Extended Warranty | PWSC | Homebuilder warranty service fees
Disaggregation of Revenue [Line Items]
Service fee and commission income	1,475	1,548	2,898	2,975
Extended Warranty | PWSC | Homebuilder warranty commissions
Disaggregation of Revenue [Line Items]
Service fee and commission income	198	188	409	362
Extended Warranty | Geminus | Vehicle service agreement fees
Disaggregation of Revenue [Line Items]
Service fee and commission income	2,757	0	3,644	0
Extended Warranty | Geminus | GAP commissions
Disaggregation of Revenue [Line Items]
Service fee and commission income	$ 16	$ 0	$ 23	$ 0