Interest Rate Swap Agreements - Summary of interest rate swap agreements (Details 1) (Interest Rate Swap, USD $)	3 Months Ended		6 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fixed rate of interest 1.00%
Derivatives, Fair Value [Line Items]
Date Entered	Jun. 01, 2012	Jun. 01, 2012	Jul. 01, 2012	Jun. 01, 2012
Effective Date	Jun. 13, 2012	Jun. 13, 2012	Jun. 13, 2012	Jun. 13, 2012
Notional Amount	$ 25,000,000	$ 25,000,000	$ 25,000,000	$ 25,000,000
Fixed Rate Of Interest	1.00%	1.00%	1.00%	1.00%
Maturity Date	Jun. 13, 2017	Jun. 13, 2017	Jun. 13, 2017	Jun. 13, 2017
Fixed rate of interest 0.87%
Derivatives, Fair Value [Line Items]
Date Entered	Jul. 30, 2012	Jul. 30, 2012	Jul. 30, 2012	Jul. 30, 2012
Effective Date	Aug. 13, 2012	Aug. 13, 2012	Aug. 13, 2012	Aug. 13, 2012
Notional Amount	$ 25,000,000	$ 25,000,000	$ 25,000,000	$ 25,000,000
Fixed Rate Of Interest	0.87%	0.87%	0.87%	0.87%
Maturity Date	Aug. 14, 2017	Aug. 14, 2017	Aug. 14, 2017	Aug. 14, 2017