Note 13 - Employee Retirement Plans (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Cap on Contribution Toward Future Retiree Medical Coverage	120.00%
Percentage of Cost to Be Paid by Employees for Retiree Medical Upon Retirement	100.00%
Defined Benefit Plan, Accumulated Benefit Obligation	$ 3,600,000	$ 3,500,000
Grading Sources	4
Defined Benefit Plan, Number of Years RP 2000 Mortality Table is Used			7
Credit Risk of Plan Assets, Long Duration Corporate Bonds	58.00%
Currency Fluctuations, Assets Invested in Non US Investments	12.00%
Liquidity Risk, Long Term Investments in Private Equity and Real Estate	10.00%
Defined Contribution Plan, Cost Recognized	$ 56,000	53,000	$ 62,000
Equity Securities [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	20.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	25.00%
Bond Investments [Member]
Defined Benefit Plan, Target Plan Asset Allocations	60.00%
Private Equity and Real Estate [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	5.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	15.00%
Commodities [Member]
Defined Benefit Plan, Target Plan Asset Allocations Range Minimum	0.00%
Defined Benefit Plan, Target Plan Asset Allocations Range Maximum	5.00%
Maximum [Member]
Number of Bonds	375
Percent to Yield	40.00%
Minimum [Member]
Number of Bonds	350
Percent to Yield	10.00%
United States Pension Plan of US Entity [Member]
Defined Benefit Plan, Voluntary Contributions by Employer	$ 73,000	65,000
United States Pension Plan of US Entity [Member] | Maximum [Member]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	0
Foreign Pension Plan [Member]
Defined Benefit Plan, Voluntary Contributions by Employer	16,000	$ 35,000
Foreign Pension Plan [Member] | Maximum [Member]
Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year	23,000
Pension Plan [Member]
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)	6,000
Defined Benefit Plan, Cash Flows Determination Approach, Change in Service and Interest Costs	(23,000)
Other Postretirement Benefit Plan [Member]
Defined Benefit Plan, Future Amortization of Prior Service Cost (Credit)	(3,000)
Defined Benefit Plan, Future Amortization of Gain (Loss)	1,000
Defined Benefit Plan, Cash Flows Determination Approach, Change in Service and Interest Costs	$ (5,000)