Business Acquisition Business Acquisitions (Supplementary Information On Unaudited Pro Forma Financial Results Of Acquisition) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Business Combinations [Abstract]
Business Acquisition, Pro Forma Revenue	$ 398,953	$ 357,571
Business Acquisition, Pro Forma Net Income (Loss)	$ 86,442	$ 91,925
Business Acquisition, Pro Forma Earnings Per Share, Basic	$ 1.87	$ 2.02
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 1.84	$ 2.00