Share Repurchases (Details) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Share Repurchases [Line Items]
Shares repurchased	857,016	4,743,926
Average price per share for repurchased shares (in dollars per share)		$ 82.76
Number of treasury shares held	90,157,342	90,157,342		85,413,416
Purchase of common stock		$ 392,588,000	$ 407,862,000
May 2012 Authorization [Member]
Share Repurchases [Line Items]
Number of shares authorized to be repurchased	10,000,000	10,000,000
Shares repurchased		1,146,946
Average price per share for repurchased shares (in dollars per share)		$ 87.21
Remaining number of shares authorized to be repurchased	2,761,343	2,761,343
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	1,000,000,000
Purchase of common stock		$ 292,565,000