Intangible Assets and Goodwill (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended			3 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 ERA Mining Machinery Limited	Mar. 31, 2012 Caterpillar Tohoku Limited	Jun. 30, 2012 Customer Relationships	Sep. 30, 2012 Customer Relationships	Dec. 31, 2011 Customer Relationships	Sep. 30, 2012 Intellectual Property	Dec. 31, 2011 Intellectual Property	Sep. 30, 2012 Other	Dec. 31, 2011 Other
Intangible assets
Weighted Amortizable Life (in years)			14 years		13 years				15 years	15 years	12 years	11 years	10 years	11 years
Gross Carrying Amount	$ 4,871		$ 4,871		$ 4,904				$ 2,827	$ 2,811	$ 1,744	$ 1,794	$ 300	$ 299
Accumulated Amortization	(723)		(723)		(554)				(330)	(213)	(303)	(244)	(90)	(97)
Net	4,148		4,148		4,350				2,497	2,598	1,441	1,550	210	202
Indefinite-lived intangible assets in process research & development	18		18		18
Total intangible assets, net	4,166		4,166		4,368
Total intangible assets, gross carrying amount	4,889		4,889		4,922
Finite-lived intangible assets acquired						194	8
Assets classified to held for sale, intangible assets									100
Accumulated amortization on held for sale intangible assets									4
Impaired finite-lived intangible assets, gross								51
Imparied finite-lived intangible assets, accumulated amortization								29
Impairment of Intangible Assets, Finite-lived								22
Amortization expense	101	91	294	135
2012	390		390
2013	383		383
2014	377		377
2015	372		372
2016	364		364
Thereafter	$ 2,574		$ 2,574