Quarterly Information (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2012	Oct. 31, 2011	Oct. 31, 2010
Quarterly Financial Information [Line Items]
Revenues	$ 1,090,001	$ 1,079,235	$ 1,057,244	$ 1,073,785	$ 1,081,343	$ 1,076,247	$ 1,060,083	$ 1,029,169	$ 4,300,265	$ 4,246,842	$ 3,495,747
Gross profit	121,585	107,607	109,328	107,365	121,751	123,403	115,560	104,864
Income from continuing operations	27,705	12,626	11,747	10,640	18,182	27,911	14,200	8,405	62,718	68,698	63,870
Loss from discontinued operations	(42)	(49)	(35)	(10)	(134)	(36)	(8)	(15)	(136)	(194)	251
Net income	$ 27,663	$ 12,577	$ 11,712	$ 10,630	$ 18,048	$ 27,875	$ 14,192	$ 8,390	$ 62,582	$ 68,504	$ 64,121
Net income per common share-Basic
Income from continuing operations	$ 0.50	$ 0.23	$ 0.22	$ 0.20	$ 0.34	$ 0.52	$ 0.27	$ 0.16	$ 1.16	$ 1.29	$ 1.23
Loss from discontinued operations
Net income per common share-Basic	$ 0.50	$ 0.23	$ 0.22	$ 0.20	$ 0.34	$ 0.52	$ 0.27	$ 0.16	$ 1.16	$ 1.29	$ 1.23
Net income per common share-Diluted
Income from continuing operations	$ 0.50	$ 0.23	$ 0.21	$ 0.20	$ 0.33	$ 0.51	$ 0.26	$ 0.16	$ 1.14	$ 1.27	$ 1.21
Loss from discontinued operations
Net income per common share-Diluted	$ 0.50	$ 0.23	$ 0.21	$ 0.20	$ 0.33	$ 0.51	$ 0.26	$ 0.16	$ 1.14	$ 1.27	$ 1.21