Note 12 - Pension and Other Postretirement Benefit Plans - For the Directors' Plan, the Change in Benefit Obligation and Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Projected benefit obligation at beginning of year	$ 22,764	$ 24,097
Interest cost	902	889
Actuarial gain	130	(1,208)
Benefits paid	(1,027)	(1,014)
Projected benefit obligation at end of year	22,769	22,764	$ 24,097
Market value of assets at beginning of year	19,924	20,509
Market value of plan assets at end of year	20,146	19,924	20,509
Accrued pension cost included in other liabilities	(2,623)	(2,840)
Directors' Plan [Member]
Projected benefit obligation at beginning of year	2,530	2,663
Service cost	42	45	54
Interest cost	97	95	116
Actuarial gain	(63)	(129)
Benefits paid	(144)	(144)
Projected benefit obligation at end of year	2,462	2,530	2,663
Market value of assets at beginning of year	0	0
Defined Benefit Plan, Contributions by Employer	144	144
Market value of plan assets at end of year	0	0	$ 0
Accrued pension cost included in other liabilities	$ (2,462)	$ (2,530)