Segment Reporting (Summary Of Segment Detail) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Segment Reporting Information [Line Items]
Net sales	$ 656,833	$ 647,237	$ 580,883	$ 608,295	$ 625,450	$ 594,565	$ 537,105	$ 536,909	$ 2,493,248	$ 2,294,029	$ 1,877,064
Depreciation and amortization									61,165	60,491	59,232
Equity earnings in unconsolidated affiliates									4,735	4,105	2,019
Earnings before income taxes									370,780	312,263	230,176
Assets	1,730,082				1,726,093				1,730,082	1,726,093	1,499,506
Equity investments in unconsolidated affiliates	20,126				19,177				20,126	19,177	15,485
Capital expenditures, net of acquired businesses									78,139	60,633	43,149
Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									1,570,140	1,440,495	1,126,007
Depreciation and amortization									36,646	36,338	33,433
Equity earnings in unconsolidated affiliates									3,966	3,302	1,859
Earnings before income taxes									227,941	211,255	155,833
Assets	845,176				888,080				845,176	888,080	702,300
Equity investments in unconsolidated affiliates	17,304				16,619				17,304	16,619	14,860
Capital expenditures, net of acquired businesses									46,816	36,423	24,355
Industrial Products [Member]
Segment Reporting Information [Line Items]
Net sales									923,108	853,534	751,057
Depreciation and amortization									18,852	19,396	20,935
Equity earnings in unconsolidated affiliates									769	803	160
Earnings before income taxes									149,249	123,871	91,084
Assets	520,739				519,730				520,739	519,730	477,154
Equity investments in unconsolidated affiliates	2,822				2,558				2,822	2,558	625
Capital expenditures, net of acquired businesses									24,083	19,442	15,250
Corporate & Unallocated [Member]
Segment Reporting Information [Line Items]
Depreciation and amortization									5,667	4,757	4,864
Earnings before income taxes									(6,410)	(22,863)	(16,741)
Assets	364,167				318,283				364,167	318,283	320,052
Capital expenditures, net of acquired businesses									$ 7,240	$ 4,768	$ 3,544