Note 11 - Accumulated Other Comprehensive (Loss) - AOCI Reclass (Details) - USD ($) $ in Thousands	3 Months Ended												12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	[1]	Dec. 31, 2015	[1]	Sep. 30, 2015	[1]	Jun. 30, 2015	[1]	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Other income (expense), net													$ 2,328	$ (915)	$ 4,077
Recognized actuarial loss													216,541	217,451	236,802
Income before Income Tax Provision													28,900	23,489	30,430
Tax impact													(7,552)	(8,748)	(6,690)
Total reclassifications for the year	$ 9,294	$ 5,100	$ 3,935	$ 3,019	$ 6,197		$ 2,286		$ 3,273		$ 2,985		21,348	14,741	23,740
Reclassification out of Accumulated Other Comprehensive Income [Member]
Income before Income Tax Provision													(337)	(892)	(2,052)
Tax impact													112	575	691
Total reclassifications for the year													(225)	(317)	(1,361)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Other income (expense), net													201	(1)	30
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Other-than-Temporary Impairment Attributable to Parent [Member]
Other income (expense), net													(151)	(454)	(1,903)
Reclassification out of Accumulated Other Comprehensive Income [Member] | Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Recognized actuarial loss													$ (387)	$ (437)	$ (179)

[1] During the fiscal year ended March 31, 2016, we recorded out-of-period adjustments that increased the income tax provision by a net amount of $1.4 million. See Note 16, "Income Taxes" in the Notes to Consolidated Financial Statements in Item 8 of this Annual Report on Form 10-K for further discussion of an out-of-period adjustment during the quarter ended December 31, 2015.