Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies - Schedule of Letters of Credit (Details)

v3.19.2
Commitments and Contingencies - Schedule of Letters of Credit (Details) - Letter of Credit - USD ($)
$ in Thousands
Jun. 30, 2019
Dec. 31, 2018
Line of Credit Facility [Line Items]    
Total letters of credit $ 8,742 $ 8,437
Insurance programs    
Line of Credit Facility [Line Items]    
Total letters of credit 4,105 4,105
Environmental remediation    
Line of Credit Facility [Line Items]    
Total letters of credit 4,182 3,877
Rail car commitments    
Line of Credit Facility [Line Items]    
Total letters of credit $ 455 $ 455