Segment Reporting (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended																12 Months Ended
	Oct. 31, 2011 segments		Jul. 31, 2011		Apr. 30, 2011		Jan. 31, 2011		Oct. 31, 2010		Jul. 31, 2010		Apr. 30, 2010		Jan. 31, 2010		Oct. 31, 2011 segments		Oct. 31, 2010		Oct. 31, 2009
Segment Reporting Information [Line Items]
Number Of Segments	4																4
External sales and revenues, net																	$ 13,958		$ 12,145		$ 11,569
Intersegment sales and revenues																	0		0		0
Sales and revenues, net	4,323	[1],[2]	3,537	[2]	3,355		2,743		3,372	[1],[3]	3,221	[1]	2,743	[1]	2,809	[1]	13,958		12,145		11,569
Net income attributable to NIC	255	[1],[2],[4]	1,400	[2],[4]	74	[4]	(6)	[4]	44	[1],[3],[4]	117	[1],[4]	43	[1],[4]	19	[1],[4]	1,723		223		320
Income tax benefit (expense)																	1,458		(23)		(37)
Segment profit (loss)																	265		246		357
Depreciation and amortization																	328		316		344
Interest expense																	247		253		251
Equity in income (loss) of non-consolidated affiliates																	(71)		(50)		46
Segment assets	12,291								9,730								12,291		9,730		10,028
Capital expenditures																	429	[5]	234		151	[5]
Truck [Member]
Segment Reporting Information [Line Items]
External sales and revenues, net																	9,690	[6]	8,205	[6]	7,294
Intersegment sales and revenues																	48	[6]	2	[6]	3
Sales and revenues, net																	9,738	[6]	8,207	[6]	7,297
Net income attributable to NIC																	336	[6]	424	[6]	147
Income tax benefit (expense)																	0	[6]	0	[6]	0
Segment profit (loss)																	336	[6]	424	[6]	147
Depreciation and amortization																	151	[6]	160	[6]	178
Interest expense																	0	[6]	0	[6]	0
Equity in income (loss) of non-consolidated affiliates																	(73)	[6]	(51)	[6]	(5)
Segment assets	2,771	[6]							2,457	[6]							2,771	[6]	2,457	[6]	2,660
Capital expenditures																	83	[5],[6]	82	[6]	65	[5]
Engine [Member]
Segment Reporting Information [Line Items]
External sales and revenues, net																	2,101	[6],[7]	2,031	[6]	2,031
Intersegment sales and revenues																	1,690	[6],[7]	955	[6]	659
Sales and revenues, net																	3,791	[6],[7]	2,986	[6]	2,690
Net income attributable to NIC																	84	[6],[7]	51	[6]	253
Income tax benefit (expense)																	0	[6],[7]	0	[6]	0
Segment profit (loss)																	84	[6],[7]	51	[6]	253
Depreciation and amortization																	120	[6],[7]	106	[6]	118
Interest expense																	0	[6],[7]	0	[6]	0
Equity in income (loss) of non-consolidated affiliates																	(4)	[6],[7]	(2)	[6]	45
Segment assets	1,849	[6],[7]							1,715	[6]							1,849	[6],[7]	1,715	[6]	1,517
Capital expenditures																	172	[5],[6],[7]	116	[6]	56	[5]
Gain On Extinguishment of Liability Related to Asset Previously Held Under Capital Lease																	10
Parts [Member]
Segment Reporting Information [Line Items]
Number Of Regional Parts Distribution Centers	11																11
External sales and revenues, net																	1,967		1,690		1,975
Intersegment sales and revenues																	188		195		198
Sales and revenues, net																	2,155		1,885		2,173
Net income attributable to NIC																	287		266		436
Income tax benefit (expense)																	0		0		0
Segment profit (loss)																	287		266		436
Depreciation and amortization																	9		7		7
Interest expense																	0		0		0
Equity in income (loss) of non-consolidated affiliates																	6		3		6
Segment assets	700								811								700		811		664
Capital expenditures																	19	[5]	8		13	[5]
Financial Services [Member]
Segment Reporting Information [Line Items]
Financing Fees And Revenue Reimbursement	11
External sales and revenues, net																	200	[8]	219	[8]	269	[8]
Intersegment sales and revenues																	91	[8]	90	[8]	79	[8]
Sales and revenues, net																	291	[8]	309	[8]	348	[8]
Net income attributable to NIC																	129	[8]	95	[8]	40	[8]
Income tax benefit (expense)																	0	[8]	0	[8]	0	[8]
Segment profit (loss)																	129	[8]	95	[8]	40	[8]
Depreciation and amortization																	28	[8]	28	[8]	25	[8]
Interest expense																	109	[8]	113	[8]	161	[8]
Equity in income (loss) of non-consolidated affiliates																	0	[8]	0	[8]	0	[8]
Segment assets	3,580	[8]							3,497	[8]							3,580	[8]	3,497	[8]	4,136	[8]
Capital expenditures																	2	[5],[8]	2	[8]	3	[5],[8]
Interest revenues																	285		270		304
Corporate and Eliminations [Member]
Segment Reporting Information [Line Items]
External sales and revenues, net																	0		0		0
Intersegment sales and revenues																	(2,017)		(1,242)		(939)
Sales and revenues, net																	(2,017)		(1,242)		(939)
Net income attributable to NIC																	887		(613)		(556)
Income tax benefit (expense)																	1,458		(23)		(37)
Segment profit (loss)																	(571)		(590)		(519)
Depreciation and amortization																	20		15		16
Interest expense																	138		140		90
Equity in income (loss) of non-consolidated affiliates																	0		0		0
Segment assets	3,391								1,250								3,391		1,250		1,051
Capital expenditures																	$ 153	[5]	$ 26		$ 14	[5]

[1] Starting with the first quarter of 2011, the Company changed its method of accruing for certain incentive compensation, specifically relating to cash bonuses, for interim reporting purposes from a ratable method to a performance-based method. The Company believes that the performance-based method is preferable because it links the accrual of incentive compensation with the achievement of performance. This change did not have an impact on our annual financial results. We have revised our previously reported Quarterly Condensed Consolidated Statements of Operations and Financial Data on a retrospective basis to reflect this change in principle based on information that would have been available as of our previous filing.

[2] In the fourth quarter of 2011, certain out-of-period adjustments were recorded related to the partial release of the Company's income tax valuation allowance. The adjustments of approximately $61 million primarily related to the classification of a deferred tax item and resulted in the Company recognizing an additional income tax benefit. The Company should have recognized the income tax benefit for this amount in the third quarter of 2011 with the release of a portion of the Company's income tax valuation allowance. Correcting the error was not material to any of the related periods.

[3] In the fourth quarter of 2010, we recorded out-of-period adjustments of $10 million. See Note 1, Summary of significant accounting policies.

[4] We record adjustments to our product warranty accrual to reflect changes in our estimate of warranty costs for products sold in prior periods. Such adjustments typically occur when claims experience deviates from historic and expected trends.

[5] Exclusive of purchases of equipment leased to others.

[6] See Note 2, Restructurings and impairments, for further discussion.

[7] In 2011, the Engine segment recognized a $10 million gain on the extinguishment of a liability related to an equipment financing transaction. Previously, such gains were not material and were recorded in Corporate.

[8] Total sales and revenues in the Financial Services segment include interest revenues of $285 million, $270 million, and $304 million for 2011, 2010, and 2009, respectively.