Cat Financial Financing Activities (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011
Allowance for credit loss activity:
Balance at beginning of year	$ 366	$ 362
Receivables written off	(24)	(210)
Recoveries on receivables previously written off	13	52
Provision for credit losses	19	168
Other	2	(6)
Balance at end of year	376	366
Customer
Allowance for credit loss activity:
Balance at beginning of year	360	357
Receivables written off	(24)	(210)
Recoveries on receivables previously written off	13	52
Provision for credit losses	18	167
Other	2	(6)
Balance at end of year	369	360
Dealer
Allowance for credit loss activity:
Balance at beginning of year	6	5
Provision for credit losses	1	1
Balance at end of year	$ 7	$ 6