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Employee Benefit Plans (Details) - USD ($)
$ in Millions
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Compensation and Retirement Disclosure [Abstract]        
Annual discretionary employer matching contributions (as a percent)     3.00%  
Employer matching contributions $ 0.7 $ 0.5 $ 1.5 $ 1.5