Summary Of Significant Accounting Policies Summary Of Significant Accounting Policies (Earnings per share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Numerator:
Net income	$ 107,769	$ 140,545	$ 266,062	$ 257,244
Less: earnings distributed to participating securities	(181)	(124)	(554)	(386)
Less: undistributed earnings allocated to participating securities	(516)	(820)	(1,169)	(1,362)
Numerator for basic earnings per share	107,072	139,601	264,339	255,496
Add back: undistributed earnings allocated to participating securities	516	820	1,169	1,362
Less: undistributed earnings reallocated to participating securities	(512)	(812)	(1,158)	(1,349)
Numerator for diluted earnings per share	$ 107,076	$ 139,609	$ 264,350	$ 255,509
Denominator:
Basic shares outstanding (shares)	350,147	373,531	359,236	376,097
Effect of dilutive securities (shares)	3,225	3,761	3,273	3,723
Diluted shares outstanding (shares)	353,372	377,292	362,509	379,820
Earnings Per Share [Abstract]
Earnings Per Share, Basic (usd per share)	$ 0.31	$ 0.37	$ 0.74	$ 0.68
Earnings Per Share, Diluted (usd per share)	$ 0.30	$ 0.37	$ 0.73	$ 0.67