Segment Reporting (Net Sales By Product Within Engine Products Segment And Industrial Products Segment) (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
Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									1,570,140		1,440,495		1,126,007
Industrial Products [Member]
Segment Reporting Information [Line Items]
Net sales									923,108		853,534		751,057
Off-Road Products [Member] | Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									376,870		327,557		222,329
On-Road Products [Member] | Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									163,934		127,107		81,874
Aftermarket Products [Member] | Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									907,306	[1]	861,393	[1]	691,899	[1]
Retrofit Emissions Products [Member] | Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									15,354		19,555		17,928
Aerospace and Defense Products [Member] | Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									106,676		104,883		111,977
Industrial Filtration Solutions Products [Member] | Industrial Products [Member]
Segment Reporting Information [Line Items]
Net sales									553,453		507,646		423,050
Gas Turbine Products [Member] | Industrial Products [Member]
Segment Reporting Information [Line Items]
Net sales									180,669		154,726		150,131
Special Applications Products [Member] | Industrial Products [Member]
Segment Reporting Information [Line Items]
Net sales									188,986		191,162		177,876
United States [Member]
Segment Reporting Information [Line Items]
Net sales									1,064,474		941,218		745,400
Europe [Member]
Segment Reporting Information [Line Items]
Net sales									678,619		653,275		545,803
Asia - Pacific [Member]
Segment Reporting Information [Line Items]
Net sales									572,163		540,874		460,470
Other [Member]
Segment Reporting Information [Line Items]
Net sales									$ 177,992		$ 158,662		$ 125,391

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