Segments Information - Assets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Segments Information
Assets	$ 2,827,098	$ 2,561,477
Operating Segments
Segments Information
Assets	2,602,291	2,258,830
Corporate, Non-Segment
Segments Information
Assets	224,807	302,647
Consumer Services and Plans | Operating Segments
Segments Information
Assets	140,992	180,295
Dealership | Operating Segments
Segments Information
Assets	1,685,916	1,715,084
Retail | Operating Segments
Segments Information
Assets	$ 775,383	$ 363,451