Amounts Charged To Expense For Stock-based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	$ 2,015		$ 793		$ 5,336		$ 2,462
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	1,818		775		5,004		2,254
Directors restricted stock grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	170	[1]	64	[1]	290	[1]	184	[1]
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	27		1		42		124
Stock appreciation rights
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation			$ (47)	[2]			$ (100)	[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 stockholders, 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 has no current plans to issue stock appreciation rights under the 2005 Amended and Restated Stock Incentive Plan.