Annual report pursuant to Section 13 and 15(d)

Fair Value Measurements - Valuation Inputs (Details)

v3.8.0.1
Fair Value Measurements - Valuation Inputs (Details) - Contingent Consideration - Recurring
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Discount rates 16.30%  
Volatility rates 24.00% 29.90%
Risk free rate of return 1.60% 0.70%
Minimum    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Discount rates   14.80%
Maximum    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Discount rates   27.80%