Accumulated Other Comprehensive Income/(Loss) (Details 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									$ (15)		$ (15)		$ (27)
Interest Expense									(667)		(611)		(593)
Reclassifications before tax	$ 133	$ 126	$ 164	$ 167	$ 122	$ 146	$ 148	$ 145	590		561		619
Tax (provision) benefit									4		(171)		(158)
Total reclassifications from Accumulated other comprehensive income/(loss)	$ 271	$ 86	$ 114	$ 115	$ 85	$ 97	$ 102	$ 100	586	[1]	384	[1]	460	[1]
Reclassifications out of Accumulated other comprehensive income/(loss) | Derivative financial instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications before tax									(72)		25		(5)
Tax (provision) benefit									27		(9)		2
Total reclassifications from Accumulated other comprehensive income/(loss)									(45)		16		(3)
Reclassifications out of Accumulated other comprehensive income/(loss) | Derivative financial instruments | Cross currency contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									(81)		28		1
Interest Expense									6		0		0
Reclassifications out of Accumulated other comprehensive income/(loss) | Derivative financial instruments | Interest rate contracts
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense									$ 3		$ (3)		$ (6)

[1] Profit attributable to Caterpillar Financial Services Corporation.