Segment Reporting (Summary Of Segment Detail) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012	Jul. 31, 2012
Segment Reporting Information [Line Items]
Net sales	$ 596,036	$ 580,883	$ 1,184,983	$ 1,189,178
Earnings before income taxes	70,849	76,419	147,527	168,436
Assets	1,718,668	1,681,389	1,718,668	1,681,389	1,730,082
Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales	353,840	370,834	724,500	764,559
Earnings before income taxes	39,025	48,418	86,449	108,296
Assets	808,349	861,191	808,349	861,191
Industrial Products [Member]
Segment Reporting Information [Line Items]
Net sales	242,196	210,049	460,483	424,619
Earnings before income taxes	32,592	30,597	65,154	64,896
Assets	550,565	506,618	550,565	506,618
Corporate & Unallocated [Member]
Segment Reporting Information [Line Items]
Earnings before income taxes	(768)	(2,596)	(4,076)	(4,756)
Assets	$ 359,754	$ 313,580	$ 359,754	$ 313,580