Share Repurchases (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Share Repurchases [Line Items]
Shares repurchased		857,016		4,743,926
Average price per share for repurchased shares (in dollars per share)	$ 66.24	$ 87.53	$ 72.94	$ 82.76
Number of treasury shares held	101,109,186		101,109,186		92,880,644
Purchase of common stock	$ 100,030	$ 75,017	$ 600,164	$ 392,588
January 2015 Authorization [Member]
Share Repurchases [Line Items]
Number of shares authorized to be repurchased	15,000,000		15,000,000
Shares repurchased	1,510,124		8,228,542
Remaining number of shares authorized to be repurchased	6,771,458		6,771,458
November 2012 Authorization [Member]
Share Repurchases [Line Items]
Authorized dollar amount for share repurchase program		$ 1,000,000		$ 1,000,000