Selected Quarterly Financial Data (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Nov. 30, 2014	Aug. 31, 2014	May 31, 2014	Feb. 28, 2014	Nov. 30, 2013	Aug. 31, 2013	May 31, 2013	Feb. 28, 2013	Nov. 30, 2014	Nov. 30, 2013	Nov. 30, 2012
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 97,894us-gaap_SalesRevenueNet	$ 79,274us-gaap_SalesRevenueNet	$ 80,827us-gaap_SalesRevenueNet	$ 74,538us-gaap_SalesRevenueNet	$ 90,980us-gaap_SalesRevenueNet	$ 77,578us-gaap_SalesRevenueNet	$ 81,705us-gaap_SalesRevenueNet	$ 83,733us-gaap_SalesRevenueNet	$ 332,533us-gaap_SalesRevenueNet	$ 333,996us-gaap_SalesRevenueNet	$ 317,612us-gaap_SalesRevenueNet
Gross profit	86,755us-gaap_GrossProfit	71,413us-gaap_GrossProfit	73,449us-gaap_GrossProfit	66,657us-gaap_GrossProfit	82,885us-gaap_GrossProfit	69,059us-gaap_GrossProfit	73,216us-gaap_GrossProfit	73,854us-gaap_GrossProfit	298,274us-gaap_GrossProfit	299,014us-gaap_GrossProfit	281,298us-gaap_GrossProfit
Income from operations	27,027us-gaap_OperatingIncomeLoss	19,431us-gaap_OperatingIncomeLoss	20,280us-gaap_OperatingIncomeLoss	14,002us-gaap_OperatingIncomeLoss	23,900us-gaap_OperatingIncomeLoss	9,661us-gaap_OperatingIncomeLoss	14,386us-gaap_OperatingIncomeLoss	15,793us-gaap_OperatingIncomeLoss	80,740us-gaap_OperatingIncomeLoss	63,740us-gaap_OperatingIncomeLoss	67,789us-gaap_OperatingIncomeLoss
Income from continuing operations	14,464	11,095	12,799	11,100	14,618	7,204	8,142	9,813	49,458	39,777	44,954
Net Income	$ 14,464us-gaap_NetIncomeLoss	$ 11,095us-gaap_NetIncomeLoss	$ 12,799us-gaap_NetIncomeLoss	$ 11,100us-gaap_NetIncomeLoss	$ 15,036us-gaap_NetIncomeLoss	$ 24,843us-gaap_NetIncomeLoss	$ 3,910us-gaap_NetIncomeLoss	$ 31,118us-gaap_NetIncomeLoss	$ 49,458us-gaap_NetIncomeLoss	$ 74,907us-gaap_NetIncomeLoss	$ 47,444us-gaap_NetIncomeLoss
Basic earnings per share from continuing operations (in dollars per share)	$ 0.29	$ 0.22	$ 0.25	$ 0.22	$ 0.28	$ 0.13	$ 0.15	$ 0.17	$ 0.97	$ 0.73	$ 0.71
Diluted earnings per share from continuing operations (in dollars per share)	$ 0.28	$ 0.22	$ 0.25	$ 0.21	$ 0.28	$ 0.13	$ 0.15	$ 0.17	$ 0.96	$ 0.72	$ 0.71

Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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