Amounts Charged to Expense for Stock-based Compensation (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	$ 4,267		$ 175		$ 8,910		$ 3,902
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	4,081		17		8,450		3,491
Directors restricted stock grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	100	[1]	103	[1]	300	[1]	309	[1]
Employee stock purchase plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock based compensation	$ 86		$ 55		$ 160		$ 102

[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 .