Redeemable Noncontrolling Interest - Caterpillar Japan Ltd. (Details) In Millions, unless otherwise specified	1 Months Ended
	Apr. 30, 2012 USD ($)	Apr. 30, 2012 JPY (¥)	Apr. 02, 2012	Mar. 31, 2012	Aug. 01, 2008
Redeemable Noncontrolling Interest Disclosure Abstract
Cat Japan, consolidated subsidiary, Caterpillar majority percentage ownership (as a percent)			100.00%	67.00%	67.00%
Cat Japan, consolidated subsidiary, MHI minority percentage ownership (as a percent)					33.00%
Noncontrolling interest, additional ownership percentage acquired by parent (as a percent)			33.00%
Cash paid to acquire remaining equity interest	$ 444	¥ 36,500