Capital Stock - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2011
Class of Stock [Line Items]
Preferred dividends description		Series A and Series B preferred stock - Dividends on our 4.0% Series A Convertible Preferred Stock and 4.0% Series B Convertible Preferred Stock (preferred stock) have been accrued from the issue date and are payable in cash as approved by the Board of Directors.
Series A and Series B preferred stock dividend rate percentage		4.00%
Preferred dividends accrued	$ 7
Series B Preferred Stock elected to convert		90,099
Common stock shares issued for conversion	760,945	760,945
Total fair value of the conversions	$ 14	$ 14