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Note 6 - Commitments and Contingencies (Details Textual) $ in Millions	1 Months Ended			9 Months Ended
	Jan. 31, 2015 USD ($)	Jul. 31, 2014 USD ($)	Jun. 30, 2007 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)	Jun. 30, 2014 USD ($)
Portland Harbor Natural Resources Trustee Council [Member]
Loss Contingency Accrual, Payments	$ 0.2	$ 0.2
Loss Contingency, Accrual, Current						$ 0.4
Voluntary Cleanup Program [Member] | Minimum [Member]
Loss Contingency, Estimate of Possible Loss				$ 0.2
Voluntary Cleanup Program [Member] | Maximum [Member]
Loss Contingency, Estimate of Possible Loss				2.4
Voluntary Cleanup Program [Member] | Estimated [Member]
Accrual for Environmental Loss Contingencies				0.3
Minimum [Member]
Estimated Cost of Epa Selected Remedy				790.0
Maximum [Member]
Estimated Cost of Epa Selected Remedy				$ 2,500.0
Estimated Time to Complete Selected Epa Remedy				18 years
Litigation Settlement, Amount			$ 0.2
Amount Spent To Complete Work Specified In Work Plans				$ 0.2	$ 0.1
Number Of Potentially Responsible Parties				100
Insurance Recoveries	$ 2.6
Letters of Credit Outstanding, Amount				$ 2.1

X

- Definition

Amount spent to complete work specified in work plans for source control work.

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The estimated cost of the remedy selected by EPA.

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Number of potentially responsible parties for Portland Harbor Superfund site.

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Total costs accrued as of the balance sheet date for environmental loss contingencies.

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