Consolidated Statement Of Shareholders' Equity - 3 months ended Mar. 31, 2016 - 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, 2015		399,896	69,493,392
Beginning balance at Dec. 31, 2015	$ 1,781,931	$ 9,997	$ 696	$ 2,381,867	$ (724,701)	$ (4,110)	$ 118,182
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income, excluding $717 attributable to redeemable noncontrolling interests	78,346				76,955		1,391
Other comprehensive loss - change in value of interest rate swaps	(2,775)					(2,775)
Dividends declared to common shareholders	(66,571)				(66,571)
Dividends declared to preferred shareholders	(135)				(135)
Distributions declared to noncontrolling interests	(1,358)						(1,358)
Common shares issued (in shares)			1,220,595
Common shares issued	181,638		$ 12	181,626
Shares issued under dividend reinvestment plan (in shares)			4,397
Shares issued under dividend reinvestment plan	646			646
Share-based compensation expense, net of forfeitures (in shares)			140,887
Share-based compensation expense, net of forfeitures	3,492		$ 2	3,490
Shares withheld for employee taxes (in shares)			(30,039)
Shares withheld for employee taxes	(4,353)		$ 0	(4,353)
Conversion and redemption of OP units (in shares)			32,037
Conversion and redemption of OP units	0			4,281			(4,281)
Contributions from noncontrolling interests	56						56
Adjustment to redeemable noncontrolling interests	(1,976)			(1,976)
Ending balance (in shares) at Mar. 31, 2016		399,896	70,861,269
Ending balance at Mar. 31, 2016	$ 1,968,941	$ 9,997	$ 710	$ 2,565,581	$ (714,452)	$ (6,885)	$ 113,990