Consolidated Statements of Cash Flows (USD $)	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
Cash flows from operating activities:
Net income	$ 67,895,000	$ 60,630,000	$ 47,525,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, plant and equipment	14,253,000	11,773,000	12,503,000
Amortization of acquired in-process research and development	0	0	6,200,000
Amortization of intangible assets with finite lives	8,091,000	7,294,000	7,592,000
Amortization of stock-based compensation	5,357,000	8,716,000	9,576,000
Amortization of fair value inventory step-up	0	0	1,520,000
Impairment of goodwill	0	13,249,000	0
Deferred financing costs	1,391,000	1,386,000	3,784,000
Loss on disposal of property, plant and equipment	7,000	116,000	62,000
Provision for (benefit from) allowance for doubtful accounts	244,000	219,000	(864,000)
Provision for excess and obsolete inventory	4,091,000	7,744,000	5,692,000
Excess income tax benefit from stock-based award exercises	(225,000)	(250,000)	(2,530,000)
Deferred income tax expense (benefit)	761,000	(7,311,000)	(1,354,000)
Changes in assets and liabilities, net of effects of acquisitions and sale of certain assets and liabilities:
Accounts receivable	64,795,000	(56,582,000)	13,319,000
Inventories	(5,224,000)	12,015,000	13,395,000
Prepaid expenses and other current assets	1,606,000	4,789,000	(7,175,000)
Other assets	737,000	(1,340,000)	72,000
Accounts payable	(54,343,000)	58,611,000	(17,862,000)
Accrued expenses and other current liabilities	(4,866,000)	484,000	(11,356,000)
Customer advances and deposits	(1,927,000)	(6,684,000)	1,071,000
Other liabilities	789,000	235,000	283,000
Interest payable	0	113,000	368,000
Income taxes payable	(6,072,000)	9,313,000	6,714,000
Net cash provided by operating activities	97,360,000	124,520,000	88,535,000
Cash flows from investing activities:
Purchases of property, plant and equipment	(7,138,000)	(7,402,000)	(13,487,000)
Purchases of other intangibles with finite lives	(50,000)	(113,000)	(100,000)
Proceeds from sale of certain assets and liabilities	0	2,038,000	0
Payments for business acquisitions, net of cash acquired	(2,850,000)	0	(205,360,000)
Net cash used in investing activities	(10,038,000)	(5,477,000)	(218,947,000)
Cash flows from financing activities:
Repurchases of common stock	(119,617,000)	0	0
Cash dividends paid	(20,135,000)	0	0
Proceeds from exercises of stock options	2,838,000	1,671,000	8,284,000
Proceeds from issuance of employee stock purchase plan shares	1,140,000	1,306,000	1,306,000
Excess income tax benefit from stock-based award exercises	225,000	250,000	2,530,000
Payment of contingent consideration related to business acquisition	(24,000)	0	0
Principal payments on other obligations	0	0	(108,000)
Origination fees associated with line of credit	(539,000)	(8,000)	(876,000)
(Transaction costs) net proceeds related to issuance of convertible senior notes	0	(118,000)	194,659,000
Net cash (used in) provided by financing activities	(136,112,000)	3,101,000	205,795,000
Net (decrease) increase in cash and cash equivalents	(48,790,000)	122,144,000	75,383,000
Cash and cash equivalents at beginning of period	607,594,000	485,450,000	410,067,000
Cash and cash equivalents at end of period	558,804,000	607,594,000	485,450,000
Cash paid during the period for:
Interest	6,407,000	6,219,000	2,109,000
Income taxes	39,498,000	35,107,000	20,787,000
Non-cash investing and financing activities:
Accrued business acquisition payments	4,170,000	1,350,000	0
Cash dividends declared	6,100,000	0	0
Accrued repurchases of common stock	2,001,000	0	0
Common stock issued in exchange for 2.0% convertible senior notes	$ 0	$ 0	$ 105,000,000