Interest Rate Swap Agreements - Summary of variable rates received and fixed rates paid under swap (Details 2) (Interest Rate Swap)	3 Months Ended	9 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013
Interest Rate Swap
Derivative [Line Items]
Variable rate received	0.16%	0.17%	0.15%	0.18%
Fixed rate paid	0.94%	0.94%	0.94%	0.94%

Average variable interest rate related to the group of interest rate derivatives.

No definition available.

Name:	nick_DerivativeAverageVariableInterestRateReceived
Namespace Prefix:	nick_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration