Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
	Oct. 31, 2012	Oct. 31, 2011
Cash flows from operating activities:
Net income	$ 7,435,000	$ 12,601,000
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization of property, plant and equipment	2,025,000	2,420,000
Amortization of intangible assets with finite lives	1,582,000	1,719,000
Amortization of stock-based compensation	745,000	873,000
Deferred financing costs	352,000	366,000
Change in fair value of contingent earn-out liability	(2,378,000)	0
Loss on disposal of property, plant and equipment	9,000	0
Provision for (benefit from) allowance for doubtful accounts	211,000	(55,000)
Provision for excess and obsolete inventory	671,000	565,000
Excess income tax benefit from stock-based award exercises	0	(19,000)
Deferred income tax expense (benefit)	1,058,000	(476,000)
Changes in assets and liabilities:
Accounts receivable	9,104,000	(3,616,000)
Inventories	3,042,000	(3,380,000)
Prepaid expenses and other current assets	198,000	407,000
Other assets	(40,000)	(18,000)
Accounts payable	(6,757,000)	(4,870,000)
Accrued expenses and other current liabilities	(7,273,000)	(6,466,000)
Customer advances and deposits	(2,586,000)	(2,074,000)
Other liabilities	518,000	225,000
Interest payable	1,500,000	1,500,000
Income taxes payable	2,462,000	(474,000)
Net cash provided by (used in) operating activities	11,878,000	(772,000)
Cash flows from investing activities:
Purchases of property, plant and equipment	(1,063,000)	(1,443,000)
Net cash used in investing activities	(1,063,000)	(1,443,000)
Cash flows from financing activities:
Repurchases of common stock	0	(78,651,000)
Cash dividends paid	(4,773,000)	(6,100,000)
Proceeds from exercises of stock options	323,000	2,241,000
Proceeds from issuance of employee stock purchase plan shares	248,000	287,000
Excess income tax benefit from stock-based award exercises	0	19,000
Payment of contingent consideration related to business acquisition	(1,000)	(63,000)
Net cash used in financing activities	(4,203,000)	(82,267,000)
Net increase (decrease) in cash and cash equivalents	6,612,000	(84,482,000)
Cash and cash equivalents at beginning of period	367,894,000	558,804,000
Cash and cash equivalents at end of period	374,506,000	474,322,000
Cash paid during the period for:
Interest	87,000	95,000
Income taxes	570,000	2,459,000
Non cash investing and financing activities:
Cash dividends declared	4,784,000	6,102,000
Accrued repurchases of common stock	$ 0	$ 4,502,000