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Related Party Transactions (Details) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Related Party Transactions
Receivable from related party	$ 195	$ 195		$ 349
USAA
Related Party Transactions
Receivable from related party	200	200		300
Due to related party	4,500	4,500		$ 5,300
USAA \| Sales and marketing
Related Party Transactions
Costs under related party agreements		5,500	$ 4,500
Accu-Trade
Related Party Transactions
Due to related party	$ 200	$ 200
Ownership percent	20.00%	20.00%
Accu-Trade \| Contra-revenue
Related Party Transactions
Costs under related party agreements	$ 200
Accu-Trade \| Cost of revenue
Related Party Transactions
Costs under related party agreements	$ 100