Summary Of Significant Accounting Policies (Computation Of Basic And Diluted Net Income Per Share Applicable To Common Shareholders) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Accounting Policies [Abstract]
Net income applicable to common shareholders	$ 96,436	$ 69,123	$ 170,746	$ 108,185
Net Income applicable to common shareholder
Basic	59,686	58,938	59,415	58,075
Effect of dilutive potential common shares:
Stock options	2,221	2,238	2,222	2,276
Restricted stock	544	322	535	230
Diluted	62,451	61,498	62,172	60,581
Net income per share applicable to common shareholders:
Basic	$ 1.62	$ 1.17	$ 2.87	$ 1.86
Diluted	$ 1.54	$ 1.12	$ 2.75	$ 1.79