Amounts Charged To Expense For Stock-based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012		Mar. 31, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	$ 1,246		$ 1,067
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	1,212		948
Directors restricted stock grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	60	[1]	60	[1]
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	(26)		55
Stock appreciation rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation			$ 4	[2]

[1] Relates to non-employee directors serving on the Parent Company's Board of Directors, all of whom have been elected by the Company's shareholders, as well as non-employee directors serving on NUAL's Board of Directors.

[2] All outstanding stock appreciation rights were exercised during 2011. The Company will no longer issue awards from the Stock Appreciation Rights Plan as a result of the 2005 Amended and Restated Stock Incentive Plan.