Cat Financial Financing Activities (Details 3) (USD $) In Millions	Sep. 30, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance for Credit Losses:
Ending Balance - individually evaluated for impairment	$ 65	$ 79
Ending Balance - collectively evaluated for impairment	294	283
Ending Balance - allowance for credit losses	359	362	376
Recorded Investment in Finance Receivables:
Ending Balance - individually evaluated for impairment	604	641
Ending Balance - collectively evaluated for impairment	19,118	19,282
Ending Balance - recorded investment in finance receivables	19,722	19,923
Customer
Allowance for Credit Losses:
Ending Balance - individually evaluated for impairment	65	79
Ending Balance - collectively evaluated for impairment	288	278
Ending Balance - allowance for credit losses	353	357
Recorded Investment in Finance Receivables:
Ending Balance - individually evaluated for impairment	604	641
Ending Balance - collectively evaluated for impairment	16,686	17,339
Ending Balance - recorded investment in finance receivables	17,290	17,980
Customer | North America
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	5,472	6,448
Customer | North America | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	5,323	6,231
Customer | North America | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	149	217
Customer | Europe
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,304	2,510
Customer | Europe | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,192	2,421
Customer | Europe | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	112	89
Customer | Asia Pacific
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	4,163	3,529
Customer | Asia Pacific | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	4,124	3,498
Customer | Asia Pacific | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	39	31
Customer | Latin America
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,433	2,426
Customer | Latin America | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,317	2,287
Customer | Latin America | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	116	139
Customer | Global Power Finance
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,918	3,067
Customer | Global Power Finance | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,707	2,904
Customer | Global Power Finance | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	211	163
Customer | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	16,663	17,341
Customer | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	627	639
Dealer
Allowance for Credit Losses:
Ending Balance - collectively evaluated for impairment	6	5
Ending Balance - allowance for credit losses	6	5
Recorded Investment in Finance Receivables:
Ending Balance - collectively evaluated for impairment	2,432	1,943
Ending Balance - recorded investment in finance receivables	2,432	1,943
Dealer | North America
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	1,735	1,291
Dealer | North America | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	1,735	1,291
Dealer | Europe
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	64	41
Dealer | Europe | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	64	41
Dealer | Asia Pacific
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	155	151
Dealer | Asia Pacific | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	155	151
Dealer | Latin America
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	478	457
Dealer | Latin America | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	478	457
Dealer | Global Power Finance
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables		3
Dealer | Global Power Finance | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables		3
Dealer | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,432	1,943
North America | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	7,058	7,522
Europe | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,256	2,462
Asia Pacific | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	4,279	3,649
Latin America | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,795	2,744
Global Power Finance | Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,707	2,907
Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	19,095	19,284
North America | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	149	217
Europe | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	112	89
Asia Pacific | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	39	31
Latin America | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	116	139
Global Power Finance | Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	211	163
Non-Performing
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	627	639
North America
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	7,207	7,739
Europe
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,368	2,551
Asia Pacific
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	4,318	3,680
Latin America
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	2,911	2,883
Global Power Finance
Recorded Investment in Finance Receivables:
Ending Balance - recorded investment in finance receivables	$ 2,918	$ 3,070