v3.19.3.a.u2
Acquisitions and divestments - Pro forma (Details) - Koma Kulshan Associates - USD ($)
$ in Millions
5 Months Ended 12 Months Ended
Dec. 31, 2018
Dec. 31, 2018
Jul. 27, 2018
Step acquisition      
Gain as a result of remeasuring to fair value of 50% equity interest immediately prior to the business combination   $ 7.2  
Intangible assets     $ 24.8
Deferred tax liabilities and deferred tax expense assumed at step acquisition     $ 0.5
Business Acquisition, Pro Forma Information [Abstract]      
Revenue contributed $ 1.1    
Net income contributed $ 0.0