Defined Contribution Plan	12 Months Ended
Dec. 31, 2018
Compensation And Retirement Disclosure [Abstract]
Defined Contribution Plan	10. Defined Contribution Plan In September 2016, the Company began to sponsor a 401(k) retirement plan in which substantially all of its full-time employees are eligible to participate. Participants may contribute a percentage of their annual compensation to this plan, subject to statutory limitations. During the years ended December 31, 2018, 2017, 2016, the Company provided $0.2 million, $0.1 million, and $0.1 million, respectively, in contributions to the plan.

The entire disclosure for an entity's employee compensation and benefit plans, including, but not limited to, postemployment and postretirement benefit plans, defined benefit pension plans, defined contribution plans, non-qualified and supplemental benefit plans, deferred compensation, share-based compensation, life insurance, severance, health care, unemployment and other benefit plans.

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