Income Taxes (Narrative) (Details) (USD $) In Thousands	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010	Jul. 31, 2009
Income Taxes
Current federal tax expense, ending balance	$ 48,943	$ 55,462	$ (2,563)
Current federal tax expense benefit period decrease	6,519	58,025
Decrease in income taxes due to reduction in pre-tax income	6,568
Increase in income taxes due to increase in pre-tax income		51,800
Increase (decrease) in pretax income	(18,766)	147,998
Current federal tax expense increase due to disallowed executive compensation		1,578
Increases in various temporary items	1,207	5,902
Decrease in current federal tax expense due to disallowed executive compensation	1,578
Increase (decrease) in current federal tax expense due to domestic manufacturing deduction	(1,491)	(3,325)
Decrease in unrecognized tax benefits related to lapses in the statute of limitations		3,027
Increase (decrease) in federal tax expenses due to nondeductible goodwill		(3,235)
Decrease in current state tax expense due to decrease in unrecognized tax benefits	2,329
Current state tax expense	250	9,337	3,304
Current state and local tax expense benefit period increase (decrease)	(9,087)	6,033
Current state and local tax expenses increase (decrease) due to pre-tax income	(657)	6,956
Current state tax expense decrease due to disallowed executive compensation	212
Current state tax expense increase due to disallowed executive compensation		212
Current state tax expense increase decrease in various temporary items	232	635
Decrease in current state tax expense due to blended tax rate	3,731
Increase (decrease) in unrecognized tax benefits		1,096
Decrease in current state tax expenses result of nondeductible goodwill		472
Income before income taxes includes foreign income (loss)	0	(8,154)	(2,659)
Increase (decrease) in net deferred tax assets	29,966	3,227
Net deferred tax assets, ending balance	16,729	46,695
Decrease in deferred tax assets due to increased intangibles liability	32,647
Decrease in deferred tax assets due to increased liability in property basis	3,614
Decrease in deferred tax assets offset by increase in deferred compensation	1,117
Decrease in deferred tax assets offset by increase in accrued expenses	1,850
Increase in deferred tax asset due to increase in product warranty reserves		3,622
Increase in deferred tax asset due to employee benefits		1,491
Decrease in deferred tax asset for unrecognized tax benefits		1,653
Capital loss carry forward expected to be realized	38	1,843
Increase in liability for unrecognized tax benefits due to federal benefit			11,031
Unrecognized tax benefits that, if recognized, would affect the company's income tax rate	21,453	20,719	19,944
Total amount of liabilities accrued for interest and penalties related to unrecognized tax benefits	12,533	13,326	17,100
Total amount of interest and penalties recognized	(995)	(2,200)	1,320
Expected decrease in unrecognized tax benefits due to resolution of uncertain tax positions	3,515
Expected decrease in interest due to resolution of uncertain tax positions	761
Expected decrease in penalties due to resolution of uncertain tax positions	$ 29