Earnings Per Share (Details Textual) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Earnings Per Share (Textual)
Options to purchase shares of common stock not included in the computation of diluted earnings per share	12.3	12.7
Repurchased shares of common stock	2.3
Average price per share	$ 61.03
Total cash outlay	$ 141,600,000
Amount remains authorized for future repurchases	1,400,000,000
Amount authorized for share repurchase program	$ 1,500,000,000