Related Party Transactions	6 Months Ended
Related Party Transactions	Jun. 30, 2015
Related Party Transactions [Abstract]
Related party transactions	Related Party Transactions Transactions with Stockholders In October 2011, as part of the acquisition of ALG, the Company entered into various data licensing and transition services agreements with Dealertrack, a former significant stockholder of the Company. In the first quarter of 2014, Dealertrack divested its holdings in the Company and was no longer a related party. Costs under these agreements included in cost of revenue for the six months ended June 30, 2014 were $0.4 million. Service Provider An executive officer of the Company is an officer of a firm that provides marketing services to the Company. For the three months ended June 30, 2015 and 2014, the Company recorded sales and marketing expense of $2.8 million and $1.3 million, respectively, related to this marketing firm. For the six months ended June 30, 2015 and 2014, the Company recorded sales and marketing expenses of $4.1 million and $1.6 million, respectively. At June 30, 2015 and December 31, 2014, the Company recorded $1.8 million and $0.9 million in prepaid expenses related to this marketing firm. At June 30, 2015, the Company recorded $0.6 million in other current assets for deposits paid to this marketing firm. The Company had no other current assets related to this marketing firm at December 31, 2014. The Company had amounts due to this marketing firm of $0.2 million at June 30, 2015. No amounts were due to this marketing firm at December 31, 2014. Additionally, for the three and six months ended June 30, 2015, the Company capitalized as property and equipment amounts paid to this marketing firm of $0.6 million. No amounts paid to this marketing firm were capitalized for the three and six months ended June 30, 2014. Transactions with USAA A former member of the Company’s board of directors is the current Head of Corporate Development at USAA, the largest stockholder and most significant affinity marketing partner of the Company. The Company has entered into arrangements with USAA to operate its Auto Buying Program. The Company has amounts due from USAA at June 30, 2015 and December 31, 2014 of $2.0 million and $1.9 million, respectively. In addition, the Company has amounts due to USAA at June 30, 2015 and December 31, 2014 of $4.2 million and $4.7 million, respectively. The Company recorded sales and marketing expense of $3.5 million and $3.2 million for the three months ended June 30, 2015 and 2014, respectively, related to service arrangements entered into with USAA, including non-cash expense associated with warrants to purchase shares of common stock (Note 8). The Company recorded sales and marketing expenses of $6.1 million and $6.2 million for the six months ended June 30, 2015 and 2014, respectively.

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.