Annual report pursuant to Section 13 and 15(d)

SEGMENT INFORMATION - Financial Information by Geographic Area (Details)

v3.19.3.a.u2
SEGMENT INFORMATION - Financial Information by Geographic Area (Details) - USD ($)
$ in Millions
3 Months Ended 12 Months Ended
Dec. 31, 2019
Sep. 30, 2019
Jun. 30, 2019
Mar. 31, 2019
Dec. 31, 2018
Sep. 30, 2018
Jun. 30, 2018
Mar. 31, 2018
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenue $ 905.8 $ 875.7 $ 880.0 $ 846.1 $ 835.3 $ 834.2 $ 876.9 $ 865.7 $ 3,507.6 $ 3,412.1 $ 3,362.2
Percentage of operating revenues                 100.00% 100.00% 100.00%
Long-lived assets 6,699.6       6,250.9       $ 6,699.6 $ 6,250.9  
Percentage of consolidated long-lived assets                 100.00% 100.00%  
U.S.                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenue                 $ 2,543.2 $ 2,405.1 $ 2,379.7
Percentage of operating revenues                 73.00% 71.00% 71.00%
Long-lived assets 3,911.5       3,457.0       $ 3,911.5 $ 3,457.0  
Percentage of consolidated long-lived assets                 58.00% 55.00%  
U.K.                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenue                 $ 303.8 $ 316.4 $ 311.2
Percentage of operating revenues                 9.00% 9.00% 9.00%
Long-lived assets 312.8       289.0       $ 312.8 $ 289.0  
Percentage of consolidated long-lived assets                 5.00% 5.00%  
Australia                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenue                 $ 289.9 $ 321.2 $ 304.0
Percentage of operating revenues                 5.00% 9.00% 9.00%
Long-lived assets 1,918.6       2,009.7       $ 1,918.6 $ 2,009.7  
Percentage of consolidated long-lived assets                 29.00% 32.00%  
Canada                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenue                 $ 170.0 $ 158.5 $ 148.9
Percentage of operating revenues                 8.00% 5.00% 4.00%
Long-lived assets 128.0       105.7       $ 128.0 $ 105.7  
Percentage of consolidated long-lived assets                 2.00% 2.00%  
Other                      
Revenues from External Customers and Long-Lived Assets [Line Items]                      
Operating revenue                 $ 200.7 $ 210.9 $ 218.4
Percentage of operating revenues                 5.00% 6.00% 7.00%
Long-lived assets $ 428.7       $ 389.5       $ 428.7 $ 389.5  
Percentage of consolidated long-lived assets                 6.00% 6.00%