Accumulated Other Comprehensive Income/(Loss) (Details 2) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other income (expense)		$ (3)	$ (4)	$ (15)	$ (10)
Interest		(194)	(169)	(558)	(499)
Reclassifications before tax		163	126	387	457
Tax (provision) benefit		(32)	(38)	(85)	(137)
Total reclassifications from Accumulated other comprehensive income/(loss)	[1]	125	86	287	315
Reclassifications out of Accumulated other comprehensive income/(loss) | Derivative financial instruments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications before tax		56	(18)	155	(64)
Tax (provision) benefit		(14)	7	(37)	23
Total reclassifications from Accumulated other comprehensive income/(loss)		42	(11)	118	(41)
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)		51	(20)	141	(69)
Interest		5	1	13	3
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		$ 0	$ 1	$ 1	$ 2

[1] Profit attributable to Caterpillar Financial Services Corporation.