Consolidated Balance Sheets (unaudited) (Parenthetical) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Statement of Financial Position [Abstract]
Preferred stock, par value per share (in dollars per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized (in shares)	4,000,000	4,000,000
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	199,000,000	198,000,000
Treasury stock, shares (in shares)	19,000,000	19,000,000