Consolidated Statements of Changes in Stockholder's Equity (USD $) In Millions, unless otherwise specified	Total	Common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income/(loss)	Noncontrolling interests
Balance at Dec. 31, 2012	$ 3,723	$ 745	$ 2	$ 2,694	$ 176	$ 106
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Profit of consolidated companies	144			141		3
Foreign currency translation, net of tax	(104)				(104)	0
Derivative financial instruments, net of tax	1				1
Balance at Mar. 31, 2013	3,764	745	2	2,835	73	109
Balance at Dec. 31, 2013	4,011	745	2	3,024	117	123
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Profit of consolidated companies	139			136		3
Foreign currency translation, net of tax	4				5	(1)
Derivative financial instruments, net of tax	(1)				(1)
Balance at Mar. 31, 2014	$ 4,153	$ 745	$ 2	$ 3,160	$ 121	$ 125