Inventories - Inventories (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Mar. 31, 2012
Inventories Net [Line Items]
Finished goods	$ 494	$ 512
Work in process	8,618	6,340
Purchased and manufactured parts	14,710	10,473
Inventories, gross	23,822	17,325
Reserve for slow moving and obsolescence	(3,039)	(2,694)
Total	$ 20,783	$ 14,631