Contingencies - Additional Information (Details) - USD ($)		1 Months Ended	3 Months Ended
	Apr. 12, 2016	Apr. 30, 2016	Mar. 31, 2016	Sep. 30, 2015	Jun. 30, 2015	Sep. 30, 2014	Sep. 30, 2011	Nov. 30, 2011
Pending Litigation | New Idria Mercury Mine | E P A Notice Letter
Loss Contingencies [Line Items]
Expense recognized							$ 1,900,000
Payments charged against the reserve			$ 1,300,000
Estimate of EPA's interim removal project costs				$ 1,600,000				$ 500,000
Accrued balance				$ 1,300,000
Total contingency accrued			1,900,000
Pending Litigation | Guadelupe River Watershed | Natural Resource Damage Claim
Loss Contingencies [Line Items]
Expense recognized			800,000
Payments charged against the reserve			500,000
Accrued balance			300,000
Settled Litigation | Patent Infringement Against Orbis Corp | Loss From Patent Infringement
Loss Contingencies [Line Items]
Accrued balance						$ 3,000,000
Loss Contingency, Range of Possible Loss, Maximum			$ 3,100,000
Contingency accrual reversal					$ 3,000,000
Subsequent Event | Pending Litigation | Guadelupe River Watershed | Natural Resource Damage Claim
Loss Contingencies [Line Items]
Original estimated project costs		$ 1,600,000
Revised estimated project costs, Low Estimate		3,300,000
Revised estimated project costs, High Estimate		$ 4,400,000
Subsequent Event | Pending Litigation | Patent Infringement Against Orbis Corp | Loss From Patent Infringement
Loss Contingencies [Line Items]
Plaintiff counter claim amount	$ 1,500,000