Note 3 - Accumulated Other Comprehensive Income - Amounts Reclassified out of Accumulated Other Comprehensive Income by Component (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Unrealized gains on available for sale investment securities	$ 185,000	$ 48,000	$ 199,000	$ 155,000
Income tax benefit (expense)	(65,000)	(17,000)	(70,000)	(54,000)
Net income	120,000	31,000	129,000	101,000
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Income tax benefit (expense)	5,000	8,000	10,000	16,000
Net income	(9,000)	(15,000)	(18,000)	(30,000)
Prior service costs	(12,000)	(12,000)	(25,000)	(25,000)
Actuarial losses	(2,000)	(11,000)	(3,000)	(21,000)
	(14,000)	(23,000)	(28,000)	(46,000)
Reclassification out of Accumulated Other Comprehensive Income [Member]
Net income	111,000	16,000	111,000	71,000
Income tax benefit (expense)	(1,235,000)	(1,369,000)	(3,950,000)	(2,774,000)
Net income	3,556,000	3,332,000	9,736,000	7,181,000
	$ 4,791,000	$ 4,871,000	$ 13,686,000	$ 10,350,000