Debt (Details) (USD $)	3 Months Ended
	Oct. 31, 2012	Jul. 31, 2012	Oct. 31, 2011	Jul. 31, 2012 Manufacturing [Member]	Oct. 31, 2011 Manufacturing [Member]	Jul. 31, 2012 Financial Services [Member]	Oct. 31, 2011 Financial Services [Member]	Jul. 31, 2012 Senior Notes [Member] Manufacturing [Member]	Nov. 02, 2011 Senior Notes [Member] Manufacturing [Member]	Oct. 31, 2011 Senior Notes [Member] Manufacturing [Member]	Jul. 31, 2012 Convertible Subordinated Debt [Member] Manufacturing [Member]	Oct. 31, 2011 Convertible Subordinated Debt [Member] Manufacturing [Member]	Jul. 31, 2012 Debt Of Majority-Owned Dealerships [Member] Manufacturing [Member]	Oct. 31, 2011 Debt Of Majority-Owned Dealerships [Member] Manufacturing [Member]	Jul. 31, 2012 Financing Arrangements and Capital Lease Obligations [Member] Manufacturing [Member]	Oct. 31, 2011 Financing Arrangements and Capital Lease Obligations [Member] Manufacturing [Member]	Jul. 31, 2012 Tax Exempt Bond [Member] Manufacturing [Member]	Oct. 31, 2011 Tax Exempt Bond [Member] Manufacturing [Member]	Jul. 31, 2012 Promissory Note [Member] Manufacturing [Member]	Oct. 31, 2011 Promissory Note [Member] Manufacturing [Member]	Jul. 31, 2012 Asset-Based Credit Facility [Member] Manufacturing [Member]	Jun. 05, 2012 Asset-Based Credit Facility [Member] Manufacturing [Member]	Nov. 30, 2011 Asset-Based Credit Facility [Member] Manufacturing [Member]	Oct. 31, 2011 Asset-Based Credit Facility [Member] Manufacturing [Member]	Jul. 31, 2012 Other [Member] Manufacturing [Member]	Oct. 31, 2011 Other [Member] Manufacturing [Member]	Jul. 31, 2012 Asset-Backed Debt [Member] Financial Services [Member]	Oct. 31, 2011 Asset-Backed Debt [Member] Financial Services [Member]	Jul. 31, 2012 Bank Revolvers [Member] Financial Services [Member]	Oct. 31, 2011 Bank Revolvers [Member] Financial Services [Member]	Jul. 31, 2012 Commercial Paper [Member] Financial Services [Member]	Oct. 31, 2011 Commercial Paper [Member] Financial Services [Member]	Jul. 31, 2012 Borrowings Secured By Operating and Finance Leases [Member] Financial Services [Member]	Oct. 31, 2011 Borrowings Secured By Operating and Finance Leases [Member] Financial Services [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Commitment Fee Amount	$ 1,000,000,000	$ 1,000,000,000
Debt instrument early redemption amount								100,000,000	50,000,000	50,000,000
Debt Instrument, Interest Rate, Stated Percentage								8.25%									6.50%
Long-term Debt				2,146,000,000	1,980,000,000	2,266,000,000	2,876,000,000	872,000,000		967,000,000	514,000,000	497,000,000	75,000,000	94,000,000	146,000,000	118,000,000	225,000,000	225,000,000	33,000,000	40,000,000	238,000,000	138,000,000	100,000,000	0	43,000,000	39,000,000	1,299,000,000	1,664,000,000	857,000,000	1,072,000,000	53,000,000	70,000,000	57,000,000	70,000,000
Less: Current portion		1,416,000,000	1,379,000,000	356,000,000	99,000,000	1,060,000,000	1,280,000,000
Net long-term debt		$ 2,996,000,000	$ 3,477,000,000	$ 1,790,000,000	$ 1,881,000,000	$ 1,206,000,000	$ 1,596,000,000