Note 9 - Pension Plans - Information on Plan Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Defined Benefit Plan, Fair Value of Plan Assets	$ 28,282	$ 28,714	$ 30,114
Cash and Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets	136	121
Equity Securities [Member]
Defined Benefit Plan, Fair Value of Plan Assets	314	351
Fixed Income Funds [Member]
Defined Benefit Plan, Fair Value of Plan Assets	1,261	1,321
Mutual Fund [Member]
Defined Benefit Plan, Fair Value of Plan Assets	26,571	26,921
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	14,834	15,224
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets	136	121
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan, Fair Value of Plan Assets	314	351
Fair Value, Inputs, Level 1 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan, Fair Value of Plan Assets	1,203	1,225
Fair Value, Inputs, Level 1 [Member] | Mutual Fund [Member]
Defined Benefit Plan, Fair Value of Plan Assets	13,181	13,527
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	13,448	13,490
Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets
Fair Value, Inputs, Level 2 [Member] | Equity Securities [Member]
Defined Benefit Plan, Fair Value of Plan Assets
Fair Value, Inputs, Level 2 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan, Fair Value of Plan Assets	58	96
Fair Value, Inputs, Level 2 [Member] | Mutual Fund [Member]
Defined Benefit Plan, Fair Value of Plan Assets	$ 13,390	$ 13,394