Amounts Charged to Expense for Stock-based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	$ 460		$ 5,905		$ 8,731
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	139	[1]	5,551	[1]	8,793	[1]
Directors restricted stock grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	248	[2]	210	[2]	180	[2]
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	173		221		178
Stock appreciation rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	$ (100)	[3]	$ (77)	[3]	$ (420)	[3]

[1] The reduction in stock grant expense includes the reversal of previously recognized expense related to performance based awards that are not expected to vest.

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

[3] All issued 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.