Note 9 - Pension Plans - Information on Plan Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017
Defined Benefit Plan, Fair Value of Plan Assets	$ 28,860	$ 28,282
Cash and Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets	616	136
Equity Securities [Member]
Defined Benefit Plan, Fair Value of Plan Assets		314
Fixed Income Funds [Member]
Defined Benefit Plan, Fair Value of Plan Assets	1,021	1,261
Mutual Fund [Member]
Defined Benefit Plan, Fair Value of Plan Assets	27,223	26,571
Fair Value, Inputs, Level 1 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	15,219	14,834
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Defined Benefit Plan, Fair Value of Plan Assets	616	136
Fair Value, Inputs, Level 1 [Member] | Equity Securities [Member]
Defined Benefit Plan, Fair Value of Plan Assets		314
Fair Value, Inputs, Level 1 [Member] | Fixed Income Funds [Member]
Defined Benefit Plan, Fair Value of Plan Assets	964	1,203
Fair Value, Inputs, Level 1 [Member] | Mutual Fund [Member]
Defined Benefit Plan, Fair Value of Plan Assets	13,639	13,181
Fair Value, Inputs, Level 2 [Member]
Defined Benefit Plan, Fair Value of Plan Assets	13,641	13,448
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	57	58
Fair Value, Inputs, Level 2 [Member] | Mutual Fund [Member]
Defined Benefit Plan, Fair Value of Plan Assets	$ 13,584	$ 13,390