XML 81 R61.htm IDEA: XBRL DOCUMENT v3.19.2
Revenue recognition - Narrative (Details)
$ in Millions
6 Months Ended
Jun. 30, 2019
USD ($)
segment
Dec. 31, 2018
USD ($)
Revenue from Contract with Customer [Abstract]    
Number of operating segments | segment 1  
Revenue, remaining performance obligation, amount $ 533.2  
Revenue, remaining performance obligation, expected timing of satisfaction, period 24 months  
Deferred costs, current $ 26.5 $ 1.2