Note 6 - Other Comprehensive Income (Detail) - Components of Other Comprehensive Income (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Unrealized holding gains on securities available for sale arising during the period before tax	$ 1,544	$ 4,839
Unrealized holding gains on securities available for sale arising during the period, tax expense (benefit)	(687)	(2,154)
Unrealized holding gains on securities available for sale arising during the period net of tax	857	2,685
Reclassification adjustment for securities gains included in net income before tax	(132)	(879)
Reclassification adjustment for securities gains included in net income, tax expense (benefit)	59	391
Reclassification adjustment for securities gains included in net income net of tax	(73)	(488)
Total securities available for sale before tax	1,412	3,960
Total securities available for sale, tax expense (benefit)	(628)	(1,763)
Total securities available for sale net of tax	784	2,197
Reclassification adjustment for amortization of prior service cost before tax	10	10
Reclassification adjustment for amortization of prior service cost, tax expense (benefit)	(5)	(5)
Reclassification adjustment for amortization of prior service cost net of tax	5	5
Reclassification adjustment for amortization of net actuarial losses before tax	1,023	816
Reclassification adjustment for amortization of net actuarial losses, tax expense (benefit)	(455)	(363)
Reclassification adjustment for amortization of net actuarial losses net of tax	568	453
Total retirement plans and post-retirement life insurance before tax	1,033	826
Total retirement plans and post-retirement life insurance, tax expense (benefit)	(460)	(368)
Total retirement plans and post-retirement life insurance net of tax	573	458
Total other comprehensive income before tax	2,445	4,786
Total other comprehensive income, tax expense (benefit)	(1,088)	(2,131)
Total other comprehensive income net of tax	$ 1,357	$ 2,655