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Employee benefit plan	12 Months Ended
Employee benefit plan	Dec. 31, 2017
Retirement Benefits [Abstract]
Employee benefit plan	Employee benefit plan The Company has established a defined contribution employee retirement plan ("Plan") in accordance with Section 401(k) of the Internal Revenue Code. Expenses related to the Plan were $1.0 million, $0.9 million and $0.8 million in 2017, 2016 and 2015, respectively.