Related Party Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Related Party Transactions
Related party prepaid expenses- current	$ 101		$ 101		$ 906
Receivable from related party	1,078		1,078		1,865
Payable to related party	5,267		5,267		4,954
Dealertrack | Cost of revenue
Related Party Transactions
Costs under related party agreements				$ 400
Marketing firm with related officer
Related Party Transactions
Amounts due to related party	200		200		200
Marketing firm with related officer | Sales and marketing
Related Party Transactions
Costs under related party agreements	2,700	$ 1,000	6,800	2,600
USAA
Related Party Transactions
Receivable from related party	1,100		1,100		1,900
Payable to related party	5,300		5,300		$ 4,700
USAA | Sales and marketing
Related Party Transactions
Costs under related party agreements	5,000	5,700	11,000	11,900
Amounts paid to marketing firm
Related Party Transactions
Property, Plant and Equipment, Additions	$ 200	$ 0	$ 800	$ 0