Note 16 - Employee Benefit Plans - Summaries of Changes in Benefit Obligations and Plan Assets and of Funded Status of Pension Plans (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Benefit obligation at beginning of year	$ 39,312	$ 40,958
Service cost	6	6
Interest cost on projected benefit obligation	1,518	1,675
Actuarial loss (gain)	1,278	(325)
Benefits paid	(2,935)	(3,002)
Benefit obligation at end of year	39,179	39,312
Change in plan assets:
Fair value of plan assets at beginning of year	33,838	35,126
Actual return on plan assets	3,495	1,714
Company contributions	0	0
Benefits paid	(2,935)	(3,002)
Fair value of plan assets at end of year	34,398	33,838
Underfunded status of the plans	(4,781)	(5,474)
Balance sheet assets (liabilities):
Other liabilities	(4,781)	(5,474)
Net amount recognized	(4,781)	(5,474)
Pension plans with accumulated benefit obligation in excess of plan assets:
Projected benefit obligation	26,327	39,312
Accumulated benefit obligation	26,327	39,309
Fair value of plan assets	$ 21,539	$ 33,838
Projected benefit obligation and net periodic pension cost assumptions:
Discount rate – projected benefit obligation	3.55%	4.05%
Discount rate – net periodic pension cost	4.05%	4.35%
Rate of compensation increase	4.00%	4.00%
Weighted average asset allocation	100.00%	100.00%
Equity Securities [Member]
Projected benefit obligation and net periodic pension cost assumptions:
Weighted average asset allocation	27.00%	25.00%
Debt Securities [Member]
Projected benefit obligation and net periodic pension cost assumptions:
Weighted average asset allocation	71.00%	73.00%
Other [Member]
Projected benefit obligation and net periodic pension cost assumptions:
Weighted average asset allocation	2.00%	2.00%
Minimum [Member]
Projected benefit obligation and net periodic pension cost assumptions:
Expected long-term rate of return on plan assets	5.15%	5.40%
Maximum [Member]
Projected benefit obligation and net periodic pension cost assumptions:
Expected long-term rate of return on plan assets	6.30%	6.75%

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

Name:	us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.