Share Repurchases (Details) (USD $)	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Share Repurchases [Line Items]
Shares repurchased	3,886,910
Average price per share for repurchased shares (in dollars per share)	$ 81.70
Number of treasury shares held	89,300,326		85,413,416
Purchase of common stock	$ 317,571,000	$ 351,112,000
May 2012 Authorization [Member]
Share Repurchases [Line Items]
Number of shares authorized to be repurchased	10,000,000
Shares repurchased	289,930
Average price per share for repurchased shares (in dollars per share)	$ 86.25
Remaining number of shares authorized to be repurchased	3,618,359
November 2012 Authorization [Member]
Share Repurchases [Line Items]
Shares repurchased	3,596,980
Average price per share for repurchased shares (in dollars per share)	$ 81.06
Authorized dollar amount for share repurchase program	1,000,000,000
Purchase of common stock	$ 292,565,000