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Commitments and Contingencies (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 1994
Jun. 30, 2019
Dec. 31, 2018
Loss Contingencies [Line Items]      
Letter of credit amount outstanding   $ 29.3 $ 29.6
Collective-bargaining arrangement, percentage of participants   58.00%  
Collective-bargaining arrangement, percentage of participants expiring in 2018     2.00%
Kansas Breach of Settlement Agreement      
Loss Contingencies [Line Items]      
Litigation settlement $ 58.7    
Surety Bond      
Loss Contingencies [Line Items]      
Outstanding surety bond   $ 2.7 $ 2.7