Repurchases Of Common Stock (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Repurchases Of Common Stock [Abstract]
Shares of common stock repurchases authorized	57,000,000
Remaining shares available for repurchase under authorization	3,081,303
Shares repurchased	4,881,000	3,952,000	1,474,000
Total cost of shares repurchased	$ 618,158	$ 367,761	$ 132,268
Average cost per share	$ 126.66	$ 93.06	$ 89.72
Shares acquired through employee surrenders	46,190	49,475	53,272
Cost of shares acquired through employee surrenders	$ 5,809	$ 4,548	$ 4,662