Income Per Share (Summary Of Basic And Diluted Earnings Per Share) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Income Per Share [Abstract]
Net income available to common stockholders	$ 47,077	$ 42,021	$ 89,734	$ 81,232
Weighted average shares outstanding-basic	128,419,745	109,761,017	127,437,970	108,430,437
Stock options	68,146	195,635	69,304	193,775
Class C Units (2007 Grant)		1,334
Unvested incentive units	135,185	208,096	120,222	185,362
Weighted average shares/units outstanding-diluted	128,623,076	110,166,082	127,627,496	108,809,574
Basic	$ 0.37	$ 0.38	$ 0.70	$ 0.75
Diluted	$ 0.37	$ 0.38	$ 0.70	$ 0.75