Summary Of Significant Accounting Policies Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Accounting Policies [Abstract]
Net income	$ 39,656	$ 48,302	$ 117,374	$ 117,157
Other Comprehensive Income (Loss)	(2,852)	0	(9,287)	0
Comprehensive Income	36,804	48,302	108,087	117,157
Net income attributable to noncontrolling interests	(1,012)	(1,249)	(3,141)	(4,161)
Comprehensive Income Attributable to the Trust	$ 35,792	$ 47,053	$ 104,946	$ 112,996