Interest Rate Swap Agreements - Summary of variable rates received and fixed rates paid under swap (Details 1) - Interest Rate Swap		1 Months Ended	12 Months Ended
	Jun. 04, 2012	Jul. 30, 2012	Mar. 31, 2018	Mar. 31, 2017
Derivative [Line Items]
Average variable rate received			1.05%	0.58%
Average fixed rate paid	1.00%	0.87%	0.91%	0.94%