Components of Postretirement Benefit Liabilities (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Beginning of year	$ 14,376	$ 12,493
Service cost for benefits earned during the period	726	622	515
Interest cost on accumulated post retirement benefit	564	554	568
Net benefit payments and expense	(263)	(271)
Actuarial loss	716	978
Accumulated postretirement benefit obligation	16,119	14,376	12,493
Liabilities:
Current liabilities	397	493
Non-currrent liabilities	15,722	13,883
Total post retirement benefit liability recognized in statement of financial position	16,119	14,376
Components included in accumulated other comprehensive income (loss):
Unrecognized net gain (loss)	(492)	205
Cumulative net periodic benefit cost (in excess of employer contribution)	$ 15,627	$ 14,581