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, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2012	Oct. 31, 2011	Jul. 31, 2013		Jul. 31, 2012		Jul. 31, 2011
Segment Reporting Information [Line Items]
Net sales	$ 632,594	$ 619,371	$ 596,036	$ 588,947	$ 656,833	$ 647,237	$ 580,883	$ 608,295	$ 2,436,948		$ 2,493,248		$ 2,294,029
Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									1,504,188		1,570,140		1,440,495
Industrial Products [Member]
Segment Reporting Information [Line Items]
Net sales									932,760		923,108		853,534
Off-Road Products [Member] | Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									358,834		376,870		327,557
On-Road Products [Member] | Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									128,446		163,934		127,107
Aftermarket Products [Member] | Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									900,419	[1]	907,306	[1]	861,393	[1]
Retrofit Emissions Products [Member] | Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									12,298		15,354		19,555
Aerospace and Defense Products [Member] | Engine Products [Member]
Segment Reporting Information [Line Items]
Net sales									104,191		106,676		104,883
Industrial Filtration Solutions Products [Member] | Industrial Products [Member]
Segment Reporting Information [Line Items]
Net sales									529,751		553,453		507,646
Gas Turbine Products [Member] | Industrial Products [Member]
Segment Reporting Information [Line Items]
Net sales									232,922		180,669		154,726
Special Applications Products [Member] | Industrial Products [Member]
Segment Reporting Information [Line Items]
Net sales									$ 170,087		$ 188,986		$ 191,162

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