Employee Benefit Plans (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost for benefits earned during the period	$ 156	$ 128	$ 311	$ 257
Interest cost on accumulated postretirement benefit	138	142	277	284
Other components	1	(4)	2	(8)
Net periodic postretirement benefit cost	$ 295	$ 266	$ 590	$ 533