Consolidated Statement Of Shareholders' Equity - 6 months ended Jun. 30, 2015 - USD ($) $ in Thousands	Total	Preferred Shares	Common Shares	Additional Paid-in Capital	Accumulated Dividends in Excess of Net Income	Accumulated Other Comprehensive Loss	Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2014		399,896	68,605,783
Beginning balance at Dec. 31, 2014	$ 1,692,556	$ 9,997	$ 687	$ 2,281,223	$ (683,991)	$ (3,515)	$ 88,155
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income, excluding $1,758 attributable to redeemable noncontrolling interests	92,118				89,818		2,300
Other comprehensive loss - change in value of interest rate swaps	(1,394)					(1,394)
Dividends declared to common shareholders	(119,795)				(119,795)
Dividends declared to preferred shareholders	(271)				(271)
Distributions declared to noncontrolling interests	(2,585)						(2,585)
Common shares issued (in shares)			427,194
Common shares issued	56,618		$ 4	56,614
Exercise of stock options (in shares)			19,739
Exercise of stock options	1,207		$ 0	1,207
Shares issued under dividend reinvestment plan (in shares)			8,226
Shares issued under dividend reinvestment plan	1,165			1,165
Share-based compensation expense, net of forfeitures (in shares)			55,407
Share-based compensation expense, net of forfeitures	6,582		$ 1	6,581
Shares withheld for employee taxes (in shares)			(35,163)
Shares withheld for employee taxes	(5,082)		$ 0	(5,082)
Conversion and redemption of OP units (in shares)			39,611
Conversion and redemption of OP units	(151)			4,072			(4,223)
Contributions from noncontrolling interests	22,347						22,347
Adjustment to redeemable noncontrolling interests	(1,749)			(1,749)
Ending balance (in shares) at Jun. 30, 2015		399,896	69,120,797
Ending balance at Jun. 30, 2015	$ 1,741,566	$ 9,997	$ 692	$ 2,344,031	$ (714,239)	$ (4,909)	$ 105,994