Quarterly report pursuant to Section 13 or 15(d)

Summary of Significant Accounting Policies - Fair Value Measurements (Details)

v3.19.2
Summary of Significant Accounting Policies - Fair Value Measurements (Details)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2019
USD ($)
Jun. 30, 2018
USD ($)
Jun. 30, 2019
USD ($)
Jun. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Aggregate maximum payout amount $ 153.0   $ 153.0    
Level 3          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Contingent consideration 75.0   75.0   $ 70.8
Change in the fair value of contingent consideration liabilities 4.4 $ (6.3) 4.3 $ (6.3)  
Level 3 | Acquisition Without Maximum Earn-out          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Contingent consideration $ 1.0   $ 1.0    
Volatility | Level 3 | Minimum          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Contingent consideration liability, measurement input 0.222   0.222    
Volatility | Level 3 | Maximum          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Contingent consideration liability, measurement input 0.300   0.300    
Discount Rate | Level 3 | Minimum          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Contingent consideration liability, measurement input 0.021   0.021    
Discount Rate | Level 3 | Maximum          
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]          
Contingent consideration liability, measurement input 0.039   0.039