XML 70 R59.htm IDEA: XBRL DOCUMENT v3.19.2
Related Party Transactions - Narrative (Details)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2019
USD ($)
joint_venture
Displays
Jun. 30, 2018
USD ($)
Jun. 30, 2019
USD ($)
joint_venture
Displays
Jun. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
Related Party Transaction [Line Items]          
Equity method investment, ownership percentage 50.00%   50.00%    
Equity method investments | $ $ 16.5   $ 16.5   $ 16.1
Management fee revenue | $ $ 2.2 $ 1.9 $ 3.9 $ 3.5  
Transit shelter joint ventures          
Related Party Transaction [Line Items]          
Equity method investment, number of investments | joint_venture 2   2    
Acquired businesses          
Related Party Transaction [Line Items]          
Equity method investment, number of investments | joint_venture 4   4    
Equity method investment, number of displays | Displays 11   11