Related Party Transactions	12 Months Ended
Dec. 31, 2017
Related Party Transactions
Related Party Transactions	15. Related Party Transactions During the years ended December 31, 2016 and 2015, the Company subleased office space to an entity that was, upon execution of the sublease in 2011, a greater than 5% stockholder. The lease required the subtenant to reimburse the Company for the allocated cost of the office space subleased. The Company had no transactions with this related party during the year ended December 31, 2017, other than the repayment of a $0.1 million security deposit in connection with the expiration of the sublease in December 2016. For the years ended December 31, 2016 and 2015, the Company recorded $0.3 million and $0.3 million, respectively, as rental income from this related entity. The Company utilized the marketing and event planning services of a company that is partially owned by one of the Company's former executives. The Company had no transactions with this related party during the year ended December 31, 2017. The Company recorded $1.4 million and $1.7 million for the expenses incurred related to the services provided by this related party for the years ended December 31, 2016 and 2015, respectively. No material amounts were due to the related party or recorded in accounts payable on the consolidated balance sheets as of December 31, 2017 and 2016.

15. Related Party Transactions

During the years ended December 31, 2016 and 2015, the Company subleased office space to an entity that was, upon execution of the sublease in 2011, a greater than 5% stockholder. The lease required the subtenant to reimburse the Company for the allocated cost of the office space subleased. The Company had no transactions with this related party during the year ended December 31, 2017, other than the repayment of a $0.1 million security deposit in connection with the expiration of the sublease in December 2016. For the years ended December 31, 2016 and 2015, the Company recorded $0.3 million and $0.3 million, respectively, as rental income from this related entity.

The Company utilized the marketing and event planning services of a company that is partially owned by one of the Company's former executives. The Company had no transactions with this related party during the year ended December 31, 2017. The Company recorded $1.4 million and $1.7 million for the expenses incurred related to the services provided by this related party for the years ended December 31, 2016 and 2015, respectively. No material amounts were due to the related party or recorded in accounts payable on the consolidated balance sheets as of December 31, 2017 and 2016.