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	232			229		3
Foreign currency translation, net of tax	241				238	3
Derivative financial instruments, net of tax	3				3
Available-for-sale securities, net of tax	1				1
Balance at Jun. 30, 2017	3,462	745	2	3,337	(753)	131
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	171			162		9
Foreign currency translation, net of tax	(191)				(189)	(2)
Derivative financial instruments, net of tax	(3)				(3)
Available-for-sale securities, net of tax	0				0
Balance at Jun. 30, 2018	$ 3,241	$ 745	$ 2	$ 3,131	$ (784)	$ 147