Remediation Obligations (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Environmental Loss Contingencies, Time Frame of Disbursements	15 years
Accrual for Environmental Loss Contingencies	$ 46,668	$ 46,362
Accrued Environmental Loss Contingencies, Current	7,880	7,880
Accrued Environmental Loss Contingencies, Noncurrent	$ 38,788	$ 38,482