Note 12 - Pension and Other Postretirement Benefit Plans - Postretirement Plan 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
Benefits paid	(1,027)	(1,014)
Market value of plan assets at end of year	20,146	19,924	20,509
Accrued pension liability included in other liabilities	(2,623)	(2,840)
Postretirement Plans [Member]
Projected benefit obligation at beginning of year	7,977	8,073
Service cost	359	382	358
Interest cost	320	300	253
Actuarial gain	(613)	(715)
Benefits paid	(65)	(63)
Projected benefit obligation at end of year	7,978	7,977	8,073
Market value of assets at beginning of year	0	0
Employer contributions	65	63
Benefits paid	(65)	(63)
Market value of plan assets at end of year	0	0	$ 0
Accrued pension liability included in other liabilities	$ (7,978)	$ (7,977)