Capital Stock (Narrative) (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Class of Stock [Line Items]
Shares authorized	800,000,000
Common stock stated value per share	$ 0.01
Common shares outstanding	226,100,000	230,500,000
Stock Repurchased During Period, Including Shares Surrendered by Employees for Withholding Taxes, Shares	6,700,000
Weighted-average cost per share repurchased	$ 46
Stock repurchase program remaining authorization	14,500,000
Preferred stock shares authorized	2,000,000
Preferred stock stated value per share	$ 1.00
Preferred Stock, Shares Outstanding	0
1997 Authorization [Member]
Class of Stock [Line Items]
Stock repurchase program remaining authorization	0
2007 Authorization [Member]
Class of Stock [Line Items]
Stock repurchase program remaining authorization	14,500,000
Common stock repurchase authorization value	$ 20.0