Consolidated Statements of Equity (USD $) In Millions, except Share data, unless otherwise specified	Total USD ($)	Common Stock Shares	Common Stock Amount USD ($)	Accumulated Other Comprehensive Loss USD ($)	Retained Earnings USD ($)	Noncontrolling Interests' Equity USD ($)
Balance at Dec. 31, 2009			$ 829	$ (6)	$ 719	$ 1
Balance, shares at Dec. 31, 2009		75,210,580
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued pursuant to equity-based plans		105,839
Proceeds from issuance of shares pursuant to equity-based plans			1
Noncontrolling interests' capital contributions			0	0	0	(10)
Stock-based compensation			1	0	0	0
Dividends declared			0	0	(78)	0
Net income (loss)	121		0	0	125	(4)
Other comprehensive income (loss)			0	1	0	0
Balance at Dec. 31, 2010			831	(5)	766	7
Balance, shares at Dec. 31, 2010		75,316,419
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued pursuant to equity-based plans		46,537
Proceeds from issuance of shares pursuant to equity-based plans			1
Noncontrolling interests' capital contributions			0	0	0	(4)
Stock-based compensation			4	0	0	0
Dividends declared			0	0	(80)	0
Net income (loss)	147		0	0	147	0
Other comprehensive income (loss)			0	(1)	0	0
Balance at Dec. 31, 2011	1,666		836	(6)	833	3
Balance, shares at Dec. 31, 2011		75,362,956
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued pursuant to equity-based plans		193,316
Proceeds from issuance of shares pursuant to equity-based plans			1
Stock-based compensation			4	0	0	0
Dividends declared			0	0	(81)	0
Net income (loss)	140		0	0		(1)
Balance at Dec. 31, 2012	$ 1,730		$ 841	$ (6)	$ 893	$ 2
Balance, shares at Dec. 31, 2012		75,556,272