Note 12 - Employee Benefit and Retirement Plans (Details Textual) - USD ($)			12 Months Ended
	Dec. 31, 2016	Dec. 31, 2013	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2016	Jan. 01, 2017
Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment					$ (6,900,000)
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate	3.77%						4.31%
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	$ 4,200,000				4,170,000
Pension Cost (Reversal of Cost)				2,700,000	3,900,000	22,200,000
Defined Contribution Plan, Employer Discretionary Contribution Amount				1,800,000	1,300,000	$ 800,000
Fair Value of the Company's Common Stock				4,800,000	$ 6,900,000
Post Retirement Medical and Life Insurance Plan [Member]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year				$ 338,000
UNITED STATES
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate				4.27%	3.92%	3.77%
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment					$ 4,170,000
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Expected Long Term Return on Assets				5.00%	5.00%	5.50%
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year				$ 4,500,000
UNITED STATES | Pension Plan [Member]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year				$ 4,500,000
UNITED STATES | Post Retirement Medical and Life Insurance Plan [Member]
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate				4.27%	3.92%	3.77%
UNITED STATES | Scenario, Forecast [Member]
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Expected Long Term Return on Assets			5.00%
UNITED KINGDOM
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate				2.80%	2.73%	3.00%
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Expected Long Term Return on Assets				3.01%	3.59%	4.77%
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year				$ 1,000,000
UNITED KINGDOM | Pension Plan [Member]
Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year				$ 1,000,000
UNITED KINGDOM | Scenario, Forecast [Member]
Defined Benefit Plan Assumptions Used Calculating Benefit Obligation Expected Long Term Return on Assets			3.00%
Maximum [Member]
Fixed Contribution Toward Medical Premium for Retirees 65 and Older		$ 28.50
Maximum [Member] | Equity Securities [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				70.00%
Maximum [Member] | Company Stock [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				20.00%
Maximum [Member] | Cash and Debt Securities [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				60.00%
Minimum [Member]
Fixed Contribution Toward Medical Premium for Retirees 65 and Older		$ 23
Minimum [Member] | Equity Securities [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				40.00%
Minimum [Member] | Company Stock [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				10.00%
Minimum [Member] | Cash and Debt Securities [Member]
Defined Benefit Plan, Plan Assets, Target Allocation, Percentage				30.00%