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Equity Incentive Plans - Schedule of Fair Value of Common Shares to be Issued Under the 2016 ESPP (Details) - 2016 Employee Stock Purchase Plan
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Dividend yield 0.00% 0.00%
Risk-free interest rate, minimum 1.07% 0.60%
Risk-free interest rate, maximum 1.45%  
Expected life 6 months 6 months 21 days
Expected volatility, minimum 27.00% 33.90%
Expected volatility, maximum 44.30%