Capital Stock (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Class of Stock [Line Items]
Shares authorized	800,000,000
Common stock stated value per share	$ 0.01
Common shares outstanding	230,500,000	235,500,000
Shares repurchased	6,200,000	100,000	100,000
Weighted-average cost per share repurchased	$ 36
Stock repurchase program remaining authorization	18,600,000
Stock split description	1% of the issued and outstanding common stock of the Company on January 1 of the current year, adjusted for any stock split.
Preferred stock shares authorized	2,000,000
Preferred stock stated value per share	$ 1.00
Preferred stock shares outstanding	0
Preferred stock shares, description	Each share of Preferred Stock, none of which is outstanding, is entitled to 10,000 votes per share (subject to adjustment) and other rights such that the value of a one ten-thousandth interest in a share of Preferred Stock should approximate the value of one share of common stock.
Preferred stock voting rights	10,000
Preferred stock purchase rights expiration date	August 20, 2010
1997 Authorization [Member]
Class of Stock [Line Items]
Shares repurchased	6,200,000	100,000	100,000
Stock repurchase program remaining authorization	1,900,000
2007 Authorization [Member]
Class of Stock [Line Items]
Shares repurchased
Stock repurchase program remaining authorization	16,700,000	16,700,000
Common stock repurchase authorization value	$ 20.0
Series A Junior Participating Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock shares authorized	500,000