Note 3 - Comprehensive Income (Details) - Changes in the Components of Accumulated Other Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period			$ 5,360
Other comprehensive income (loss)	$ (3,580)	$ 2,874	(1,274)	$ 6,409
Balance, end of period	4,086		4,086
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	7,654	2,442	5,281	(1,004)
Other comprehensive income (loss) before reclassifications	(2,971)	2,941	(550)	6,407
Amounts reclassified from accumulated other comprehensive income	(606)	(67)	(654)	(87)
Other comprehensive income (loss)	(3,577)	2,874	(1,204)	6,320
Balance, end of period	4,077	5,316	4,077	5,316
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	12	100	79	11
Other comprehensive income (loss) before reclassifications	0	2	(65)	94
Amounts reclassified from accumulated other comprehensive income	(3)	(2)	(5)	(5)
Other comprehensive income (loss)	(3)	0	(70)	89
Balance, end of period	9	100	9	100
AOCI Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance, beginning of period	7,666	2,542	5,360	(993)
Other comprehensive income (loss) before reclassifications	(2,971)	2,943	(615)	6,501
Amounts reclassified from accumulated other comprehensive income	(609)	(69)	(659)	(92)
Other comprehensive income (loss)	(3,580)	2,874	(1,274)	6,409
Balance, end of period	$ 4,086	$ 5,416	$ 4,086	$ 5,416