Retiree Benefits - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Oct. 26, 2012	Apr. 27, 2012	Oct. 26, 2012
Maximum percentage of participant's compensation matched by employer			6.00%
Additional defined benefit contribution percentage of eligible employee compensation, minimum			1.00%
Additional defined benefit contribution percentage of eligible employee compensation, maximum			5.00%
Defined benefit contribution plan expense			$ 5.6
Curtailment charges	10.4	1.1
Assumed annual rate of increase in the per capita cost of covered health care benefits			7.50%
Assumed percentage decrease in per capita cost of covered health care benefits rate			0.50%
Ultimate health care cost trend rate			5.00%
Year that rate reaches ultimate trend rate	2018		2018
Description of the change in the per capita cost of covered health care benefits rate			The per capita cost of covered health care benefits rate is assumed to decrease 0.5% per year to an ultimate rate of 5% by fiscal 2018, and remain at that level thereafter.
Increase in assumed health care cost trend rates each year			1.00%
Effect of one percentage point increase in the assumed health care cost trend rates on accumulated postretirement benefit obligation			1.0
Effect of one percentage point increase in the assumed health care cost trend rates on service cost and interest cost components			0.1
Effect of one percentage point decrease in the assumed health care cost trend rates on accumulated postretirement benefit obligation			0.9
Effect of one percentage point decrease in the assumed health care cost trend rates on service cost and interest cost components			0.1
Decrease in assumed health care cost trend rates each year			1.00%
U.S. Pension Plans [Member]
Investment goals			The plan's assets are invested to maintain funded ratios over the long-term while managing the risk that funded ratios fall meaningfully below 100%. While this objective is based on a long-term investment horizon, it is desirable that interim fluctuations in funded status should be limited by increasing correlation between assets and liabilities. The desired investment return objective is a long-term average annual real rate of return on assets that is approximately 3.75% greater than the assumed inflation rate. The target rate of return is based upon an analysis of historical returns supplemented with an economic and structural review for each asset class. There is no assurance that these objectives will be met.
Maximum funded ratios			100.00%
Percentage over the assumed inflation rate at which the annual real rate of return on assets is targeted			3.75%
Non-U.S. Pension Plans [Member]
Investment goals			The objectives of the non-U.S. plans are as follows the acquisition of suitable assets of appropriate liquidity which will generate income and capital growth and, together with new contributions from members and the employer, will meet the cost of the current and future benefits which the plan provides; to limit the risk of the assets failing to meet the liabilities over the long term and; to minimize the long term costs of the plan by maximizing the return on the assets.
Minimum [Member]
Percentage of participant salary deferral contributions matched by employer			25.00%
Expected contributions to employee pension plans for 2013	180		180
Maximum [Member]
Percentage of participant salary deferral contributions matched by employer			50.00%
Expected contributions to employee pension plans for 2013	190		190
Joy Global Pension Plan [Member]
Additional postretirement benefits	$ 1.0
Other Postretirement Benefits Plans [Member]
Description of plan amendment			In 1993, our Board of Directors approved a general approach that culminated in the elimination of all Company contributions towards postretirement health care benefits. Increases in costs paid by us were capped for certain plans beginning in 1994 extending through 1998 and Company contributions were eliminated as of January 11, 1999 for most employee groups, excluding Joy, certain early retirees, and specific discontinued operation groups. For Joy, based upon existing plan terms, future eligible retirees will participate in a premium cost-sharing arrangement which is based upon age as of March 1, 1993 and position at the time of retirement. Active employees under age 45 as of March 1, 1993 and any new hires after April 1, 1993 will be required to pay 100 of the applicable premium.
Maximum age of active employees required to pay all applicable premium for postretirement healthcare benefits			45
Percentage of premium for postretirement healthcare benefits required to be paid			100.00%