Consolidated Balance Sheet (Unaudited) (Parenthetical) (USD $)	Jun. 30, 2011	Dec. 31, 2010
Stockholders' Equity:
Preferred stock, par value per share	$ 0.01	$ 0.01
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value per share	$ 0.01	$ 0.01
Common stock, shares authorized	1,000,000,000	1,000,000,000
Common stock, shares issued	690,577,000	690,231,000
Common stock, shares outstanding	488,205,000	528,069,000
Common stock in treasury at cost, shares	202,372,000	162,162,000