Consolidated Statements of Changes in Shareholder's Equity - USD ($) $ in Millions	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income/(loss)	Noncontrolling interests
Balance at Dec. 31, 2017	$ 3,264	$ 745	$ 2	$ 2,969	$ (592)	$ 140
Increase (Decrease) in Shareholder's Equity [Roll Forward]
Profit of consolidated companies	302			287		15
Foreign currency translation, net of tax	(241)				(233)	(8)
Derivative financial instruments, net of tax	(3)				(3)
Balance at Sep. 30, 2018	3,322	745	2	3,256	(828)	147
Balance at Jun. 30, 2018	3,241	745	2	3,131	(784)	147
Increase (Decrease) in Shareholder's Equity [Roll Forward]
Profit of consolidated companies	131			125		6
Foreign currency translation, net of tax	(50)				(44)	(6)
Derivative financial instruments, net of tax	0				0
Balance at Sep. 30, 2018	3,322	745	2	3,256	(828)	147
Balance at Dec. 31, 2018	2,849	745	2	2,874	(925)	153
Increase (Decrease) in Shareholder's Equity [Roll Forward]
Profit of consolidated companies	323			306		17
Foreign currency translation, net of tax	(132)				(127)	(5)
Derivative financial instruments, net of tax	(41)				(41)
Adjustment to adopt new accounting guidance | Accounting Standards Update 2018-02	0			(97)	97
Balance at Sep. 30, 2019	2,999	745	2	3,083	(996)	165
Balance at Jun. 30, 2019	3,034	745	2	2,954	(831)	164
Increase (Decrease) in Shareholder's Equity [Roll Forward]
Profit of consolidated companies	135			129		6
Foreign currency translation, net of tax	(165)				(160)	(5)
Derivative financial instruments, net of tax	(5)				(5)
Balance at Sep. 30, 2019	$ 2,999	$ 745	$ 2	$ 3,083	$ (996)	$ 165