Segment Reporting (Net Sales By Product Within Engine Products Segment And Industrial Products Segment) (Details) (USD $) In Thousands	3 Months Ended								12 Months Ended
	Jul. 31, 2011	Apr. 30, 2011	Jan. 31, 2011	Oct. 31, 2010	Jul. 31, 2010	Apr. 30, 2010	Jan. 31, 2010	Oct. 31, 2009	Jul. 31, 2011		Jul. 31, 2010		Jul. 31, 2009
Net sales	$ 625,450	$ 594,565	$ 537,105	$ 536,909	$ 515,243	$ 497,619	$ 436,122	$ 428,080	$ 2,294,029		$ 1,877,064		$ 1,868,629
Engine Products [Member] | Off-Road Products [Member]
Net sales									327,557		222,329		243,691
Engine Products [Member] | Aerospace And Defense Products [Member]
Net sales									104,883		111,977		119,094
Engine Products [Member] | On-Road Products [Member]
Net sales									127,107		81,874		71,958
Engine Products [Member] | Aftermarket Products [Member]
Net sales									861,393	[1]	691,899	[1]	561,846	[1]
Engine Products [Member] | Retrofit Emissions Products [Member]
Net sales									19,555		17,928		31,096
Industrial Products [Member] | Industrial Filtration Solutions Products [Member]
Net sales									507,646		423,050		477,908
Industrial Products [Member] | Gas Turbine Products [Member]
Net sales									154,726		150,131		206,760
Industrial Products [Member] | Special Applications Products [Member]
Net sales									191,162		177,876		156,276
Engine Products [Member]
Net sales									1,440,495		1,126,007		1,027,685
Industrial Products [Member]
Net sales									853,534		751,057		840,944
Corporate & Unallocated [Member]
Net sales

[1] Includes replacement part sales to the Company's OEM Customers.