Commitments and Contingencies (Tables)

6 Months Ended

Jun. 30, 2016

Commitments and Contingencies Disclosure [Abstract]

Summary of Environmental Liability Associated with Potsdam

A summary of the changes to the environmental remediation liability associated with the Potsdam environmental remediation liability follows:

	Six Months Ended June 30,
	2016		2015
Beginning balance	$	5,221	$	5,142
Accretion expense		—		40
Ending balance	$	5,221	$	5,182