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, 2016	$ 2,985	$ 745	$ 2	$ 3,108	$ (995)	$ 125
Increase (Decrease) in Shareholder's Equity [Roll Forward]
Profit of consolidated companies	320			315		5
Foreign currency translation, net of tax	395				389	6
Derivative financial instruments, net of tax	0				0
Balance at Sep. 30, 2017	3,700	745	2	3,423	(606)	136
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