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Goodwill and Intangible Assets - Intangible Assets Subject to Amortization (Details) - USD ($)
$ in Millions
Mar. 31, 2021
Dec. 31, 2020
Acquired Finite-Lived Intangible Assets [Line Items]    
Cost $ 30.5 $ 39.6
Carrying Value 25.4 34.6
Pipeline space    
Acquired Finite-Lived Intangible Assets [Line Items]    
Cost 39.6 39.6
Carrying Value 34.4 34.6
Intangible lease liability    
Acquired Finite-Lived Intangible Assets [Line Items]    
Cost 9.1 0.0
Carrying Value $ 9.0 $ 0.0