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	117			115		2
Foreign currency translation, net of tax	80				80	0
Derivative financial instruments, net of tax	2				2
Balance at Mar. 31, 2017	3,184	745	2	3,223	(913)	127
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	95			91		4
Foreign currency translation, net of tax	71				65	6
Derivative financial instruments, net of tax	(6)				(6)
Balance at Mar. 31, 2018	$ 3,424	$ 745	$ 2	$ 3,060	$ (533)	$ 150