Related Parties (Details) - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Related Parties        
Cash payments $ 0.3   $ 0.3  
Accounts Receivable 0.1   $ 0.1  
Option to extend     false  
Other income 0.3   $ 0.4  
Flagship | Services agreement        
Related Parties        
Payment of general and administrative expenses   $ 0.3   $ 0.5
Cash payments   $ 0.2   $ 0.4
Amount due to related party $ 0.0   $ 0.0