Condensed Consolidated Statements of Cash Flows (USD $)	6 Months Ended
	Jan. 31, 2012	Jan. 31, 2011
Cash flows from operating activities:
Net income	$ 18,422,000	$ 41,752,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, plant and equipment	4,781,000	6,620,000
Amortization of intangible assets with finite lives	3,411,000	3,891,000
Amortization of stock-based compensation	1,909,000	2,859,000
Deferred financing costs	746,000	699,000
Loss (gain) on disposal of property, plant and equipment	2,000	(1,000)
(Benefit from) provision for allowance for doubtful accounts	(50,000)	315,000
Provision for excess and obsolete inventory	1,616,000	932,000
Excess income tax benefit from stock-based award exercises	(82,000)	(113,000)
Deferred income tax (benefit) expense	(1,953,000)	358,000
Changes in assets and liabilities, net of effects of acquisition:
Accounts receivable	9,949,000	54,661,000
Inventories	(5,007,000)	(7,350,000)
Prepaid expenses and other current assets	(255,000)	1,520,000
Other assets	(23,000)	711,000
Accounts payable	(4,833,000)	(54,453,000)
Accrued expenses and other current liabilities	(9,003,000)	(11,075,000)
Customer advances and deposits	(2,963,000)	6,087,000
Other liabilities	446,000	350,000
Interest payable	22,000	0
Income taxes payable	(5,935,000)	(3,523,000)
Net cash provided by operating activities	11,200,000	44,240,000
Cash flows from investing activities:
Purchases of property, plant and equipment	(2,660,000)	(3,350,000)
Purchases of other intangibles with finite lives	0	(50,000)
Payments for business acquisitions	0	(2,550,000)
Net cash used in investing activities	(2,660,000)	(5,950,000)
Cash flows from financing activities:
Repurchases of common stock	(157,745,000)	(46,804,000)
Cash dividends paid	(12,202,000)	(6,915,000)
Proceeds from exercises of stock options	2,587,000	1,012,000
Proceeds from issuance of employee stock purchase plan shares	556,000	587,000
Excess income tax benefit from stock-based award exercises	82,000	113,000
Payment of contingent consideration related to business acquisition	(157,000)	0
Origination fees related to line of credit	(249,000)	(539,000)
Net cash used in financing activities	(167,128,000)	(52,546,000)
Net decrease in cash and cash equivalents	(158,588,000)	(14,256,000)
Cash and cash equivalents at beginning of period	558,804,000	607,594,000
Cash and cash equivalents at end of period	400,216,000	593,338,000
Cash paid during the period for:
Interest	3,193,000	3,215,000
Income taxes	12,481,000	24,204,000
Non cash investing and financing activities:
Business acquisition liabilities	0	4,103,000
Cash dividends declared	$ 5,352,000	$ 6,699,000