Note 13 - Postretirement Medical Benefits (Tables) - Postretirement Health Coverage [Member]

12 Months Ended

Dec. 31, 2016

Notes Tables

Schedule of Changes in Projected Benefit Obligations [Table Text Block]

(In thousands)	2016			2015
Change in Benefit Obligation
Obligation at beginning of year	$	16,204		$	14,792
Service cost		637			739
Interest cost		683			649
Actuarial (gain) loss		(660	)		313
Participant contributions		153			129
Benefit payments		(462	)		(418	)
Obligation at end of year	$	16,555		$	16,204

Schedule of Net Benefit Costs [Table Text Block]

(In thousands)	2016			2015
Service cost	$	637		$	739
Interest cost		683			649
Recognized prior service cost		50			51
Amortization of net actuarial loss		-			42
Net periodic benefit cost	$	1,370		$	1,481
Major assumptions:
Discount rate used to determine net periodic benefit cost		4.34	%		3.92	%
Discount rate used to determine benefit obligation as of year end		4.12			4.34
Retiree participation rate (Plan 1)		100.00			100.00
Retiree participation rate (Plan 2)		72.00			72.00

Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block]

(In thousands)	1% Increase		1% Decrease
Effect on total of service and interest cost components of net periodic postretirement health care benefit cost	$	335	$	(250	)
Effect on accumulated postretirement benefit obligation		3,366		(2,612	)

Schedule of Expected Benefit Payments [Table Text Block]

(In thousands)	Postretirement Medical Benefits
2017	$	416
2018		451
2019		481
2020		516
2021		573
2022-2026		3,507
Total	$	5,944

Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]

(In thousands)	2016			2015
Unrecognized net actuarial (gain) loss	$	(93	)	$	566
Unrecognized prior service cost		75			125
Total	$	(18	)	$	691

Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year [Table Text Block]

(In thousands)	Postretirement Medical Benefits
Unrecognized prior service cost	$	49
Total	$	49