Repurchases Of Common Stock (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Repurchases Of Common Stock [Abstract]
Shares repurchased	576,000	687,000
Total cost of shares repurchased	$ 70,279,000	$ 63,778,000
Average cost per share	$ 122.04	$ 92.82
Shares acquired through employee surrenders	40,537	45,181
Cost of shares acquired through employee surrenders	$ 5,000,000	$ 4,100,000