Income Taxes - Tax Effects of Temporary Difference (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Deferred tax assets
Credits and net operating loss carryforwards	$ 3,287	$ 3,749	$ 3,975
Share-based compensation expense	1,134	1,332	1,441
Accrued compensation	934	1,211	895
Reserves and allowances	1,231	1,018	439
Capital loss carryforward	0	428	424
Other, net	1,021	645	729
Gross deferred tax assets	7,607	8,383	7,903
Valuation allowance	0	(428)	(424)
Total deferred tax assets	7,607	7,955	7,479
Deferred tax liabilities
Property, plant and equipment	(1,256)	(1,111)	(458)
Total deferred tax liabilities	(1,256)	(1,111)	(458)
Net deferred tax assets	$ 6,351	$ 6,844	$ 7,021