Note 13 - Accumulated Other Comprehensive Income - Amounts Reclassified Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Other expense		$ (4,923)	$ (4,536)
Total before tax		17,514	15,176
Tax benefit		(5,254)	(5,615)
Net income		12,260	9,561
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Other expense	[1]	(151)	(192)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Prior Service Attributable to Parent [Member]
Other expense	[1]	11	11
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Total before tax		(140)	(181)
Tax benefit		60	78
Net income		$ (80)	$ (103)

[1] These accumulated other comprehensive income components are included in the computation of net periodic pension cost (See Note 9 of the Notes to Consolidated Financial Statements "Pension and Other Postretirement Benefit Plans".)