Annual report pursuant to Section 13 and 15(d)

Equity-Based Compensation - Option-Pricing Formula (Details)

v3.8.0.1
Equity-Based Compensation - Option-Pricing Formula (Details)
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Schedule of stock options      
Risk-free interest rate, minimum 1.32% 0.71% 0.26%
Risk-free interest rate, maximum 2.41% 2.51% 2.42%
Expected volatility, minimum 38.00% 38.00% 32.00%
Expected volatility, maximum 55.00% 64.00% 64.00%
Expected dividend yield 0.00% 0.00% 0.00%
Minimum      
Schedule of stock options      
Expected term 3 years 1 year 1 year
Maximum      
Schedule of stock options      
Expected term 10 years 10 years 10 years