Accumulated Other Comprehensive Income/(Loss) (Details 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018		Dec. 31, 2017		Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)									$ (23)		$ (15)		$ (15)
Interest Expense									(757)		(667)		(611)
Reclassifications before tax	$ 46	$ 163	$ 100	$ 124	$ 133	$ 126	$ 164	$ 167	433		590		561
Tax (provision) benefit									(108)		4		(171)
Total reclassifications from Accumulated other comprehensive income/(loss)	$ 18	$ 125	$ 71	$ 91	$ 271	$ 86	$ 114	$ 115	305	[1]	586	[1]	384	[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									167		(72)		25
Tax (provision) benefit									(38)		27		(9)
Total reclassifications from Accumulated other comprehensive income/(loss)									129		(45)		16
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)									148		(81)		28
Interest Expense									19		6		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									$ 0		$ 3		$ (3)

[1] Profit attributable to Caterpillar Financial Services Corporation.