XML 74 R59.htm IDEA: XBRL DOCUMENT v3.21.1
Schedule of Intangible Assets (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]    
Amortizable intangible assets, gross $ 123.5 $ 123.5
Accumulated intangible asset amortization (60.7) (54.0)
Amortizable intangible assets, net $ 62.8 69.5
Average useful life of finite-lived intangible assets 15 years  
Contract-Based Intangible Assets [Member]    
Finite-Lived Intangible Assets [Line Items]    
Amortizable intangible assets, gross $ 54.6 54.6
Accumulated intangible asset amortization (32.0) (29.9)
Amortizable intangible assets, net 22.6 24.7
Customer-Related Intangible Assets [Member]    
Finite-Lived Intangible Assets [Line Items]    
Amortizable intangible assets, gross 68.9 68.9
Accumulated intangible asset amortization (28.7) (24.1)
Amortizable intangible assets, net $ 40.2 $ 44.8