Share Repurchase Program and Treasury Stock (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
Share Repurchase Program and Treasury Stock (Textuals) [Abstract]
Authorized amount under share repurchase program	$ 2,250,000,000
Remaining Amount to Repurchase under the program	365,100,000
Shares Purchased Under Share Repurchase Program	20,500,000
Treasury Stock, Value, Acquired, Cost Method	$ 72,300,000	$ 63,721,000	$ 278,672,000
Number of shares repurchased	341,109	361,777
Average price of share repurchased, per share	$ 211.94	$ 176.11
Exercise of stock options and restricted stock units, shares reissued	117,014	220,078