Interest Rate Swap Agreements - Summary of variable rates received and fixed rates paid under swap (Details 3) (Swap)	3 Months Ended
Jun. 30, 2013	Jun. 30, 2012
Swap
Derivative [Line Items]
Variable rate received	0.20%	0.24%
Fixed rate paid	0.94%	1.00%

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