Noncontrolling Interests (Effect Of Changes In Ownership Interest In Subsidiaries) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Noncontrolling Interests [Abstract]
Net income attributable to common shareholders	$ 142,166	$ 30,703	$ 21,763	$ 88,758	$ 46,850	$ 11,840	$ (16,597)	$ 7,286	$ 283,390	$ 49,379	$ 23,216
Increase in equity for conversion of operating partnership units									8,994	592	3,528
Decrease in additional-paid-in-capital for purchase of remaining non-controlling ownership interests in three consolidated joint ventures									(19,549)	0	0
Change in common equity and net transfers from non-controlling interests									$ 272,835	$ 49,971	$ 26,744