Quarterly report pursuant to Section 13 or 15(d)

Remediation Obligations (Details)

v3.7.0.1
Remediation Obligations (Details) - USD ($)
$ in Thousands
3 Months Ended
Mar. 31, 2017
Dec. 31, 2016
Commitments and Contingencies Disclosure [Abstract]    
Environmental Loss Contingencies, Time Frame of Disbursements 15 years  
Accrual for Environmental Loss Contingencies $ 45,630 $ 45,636
Accrued Environmental Loss Contingencies, Current 4,237 4,237
Accrued Environmental Loss Contingencies, Noncurrent $ 41,393 $ 41,399