Note 2 - Accumulated Other Comprehensive Income (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reclassification of Tax Effects from AOCI
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent		35.00%	35.00%	35.00%
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Retained Earnings [Member]
Reclassification of Tax Effects from AOCI		$ 633
AOCI Attributable to Parent [Member]
Reclassification of Tax Effects from AOCI		(633)
ASU 2018-02 [Member] | Retained Earnings [Member]
Reclassification of Tax Effects from AOCI		633
ASU 2018-02 [Member] | AOCI Attributable to Parent [Member]
Reclassification of Tax Effects from AOCI		$ (633)