Note 21 - Contingencies (Details Textual)	12 Months Ended
	Dec. 31, 2018 USD ($) mi² Subsidiary Site	Dec. 31, 2017 USD ($)
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 17,411,000	$ 17,511,000
Accrual for Environmental Loss Contingencies, Period Increase (Decrease)	1,055,000
Accrual for Environmental Loss Contingencies, Payments	1,155,000
Bayonne [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	608,000
Clifton and Carlstadt [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	1,827,000
Berrys Creek Site [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 9,647,000
Number of Subsidiaries Notice Received | Subsidiary | Subsidiary	2
Environmental Exit Costs, Reasonably Possible Losses, Estimated Share	2.40%
Maybrook Site [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 329,000
Harriman Site [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	3,365,000
Harriman Site [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Site Contingency Loss Exposure, Estimated Range	2,000,000
Harriman Site [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Site Contingency Loss Exposure, Estimated Range	7,000,000
Scientific Chemical Processing SCP Superfund Site [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 732,000
Number of Other Sites Named PRP of SCP Superfund Site | Site	130
Site Contingency, Recovery from Third Party of Environmental Remediation Cost	$ 468,000
Newark Bay Complex Litigation [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 0
Site Contingency Clean Up Plan, Miles of Clean Up | mi²	8.3
Amount of Estimated Cost to Clean Up Site that the Company is Not Exposed	$ 1,380,000,000
Other Non-current Liabilities [Member]
Loss Contingencies [Line Items]
Accrual for Environmental Loss Contingencies	$ 16,599,000	$ 16,976,000