Contingencies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Site Contingency [Line Items]
Statutory period	20 years
Possible royalty repayment	$ 4,100,000
Accrual for environmental loss contingencies	9,100,000	$ 9,700,000
Loss contingency, range of possible loss, minimum	0
Loss contingency, range of possible loss, maximum	5,300,000
Picton, Ontario Facility
Site Contingency [Line Items]
Increase due to charge to establish a liability for environmental investigation and remediation activities	$ 1,500,000	$ 3,300,000