Mandatory Convertible Preferred Stock (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011	Apr. 01, 2014 Mandatory Convertible Preferred Stock Minimum Conversion Rate [Member]	Apr. 01, 2014 Mandatory Convertible Preferred Stock Maximum Conversion Rate [Member]
Mandatory Convertible Preferred Stock additional (Textuals) [Abstract]
Convertible preferred stock, shares issued upon conversion				2.7454	3.4317
Mandatory Convertible Preferred Stock (Textuals) [Abstract]
Mandatory convertible preferred stock, outstanding	10,000,000	10,000,000	10,000,000
Issue price preferred stock		$ 50.00
Mandatory convertible preferred stock, dividends on each share	5.875%
Mandatory convertible preferred stock, liquidation preference	$ 50	$ 50.00	$ 50
Preferred stock, dividend payment terms	Dividends will accrue and accumulate from the date of issuance and, to the extent that we are legally permitted to pay a dividend and the Board of Directors declares a dividend payable, we will pay dividends in cash on January 1, April 1, July 1 and October 1 of each year, commencing on July 1, 2011 and ending on April 1, 2014.
Payments of Dividends, Preferred Stock and Preference Stock	$ 7	$ 0
Dividends payable, date declared, day, month and year	Mar. 06, 2012
Dividends payable, amount per share	$ 0.7344
Dividends payable, amount	$ 7
Dividends payable, date to be paid, day, month and year	Apr. 02, 2012
Dividends payable, date of record, day, month and year	Mar. 15, 2012