Consolidated Statement Of Shareholders' Equity - USD ($) $ in Thousands	Total	Preferred Shares	Common Shares	Additional Paid-in Capital	Accumulated Dividends in Excess of Net Income	Accumulated Other Comprehensive (Loss) Income	Noncontrolling Interests	Common Shares Additional Paid-in Capital
Beginning balance (in shares) at Dec. 31, 2017		405,896	73,090,877
Beginning balance at Dec. 31, 2017	$ 2,391,514	$ 159,997	$ 733	$ 2,855,321	$ (749,367)	$ 22	$ 124,808
Increase (Decrease) in Stockholders' Equity [Roll Forward]
January 1 adoption of new accounting standard - See Note 2	(6,028)				(6,028)
Net income, excluding amounts attributable to redeemable noncontrolling interests	189,724				187,400		2,324
Other comprehensive (loss) income - change in fair value of interest rate swaps	105					105
Dividends declared to common shareholders	(221,623)				(221,623)
Dividends declared to preferred shareholders	(6,031)				(6,031)
Distributions declared to noncontrolling interests	(4,010)						(4,010)
Shares issued (in shares)			612,727
Shares issued	77,371		$ 6					$ 77,365
Exercise of stock options (in shares)			93,593
Exercise of stock options	4,041		$ 1	4,040
Shares issued under dividend reinvestment plan (in shares)			13,750
Shares issued under dividend reinvestment plan	1,647			1,647
Share-based compensation expense, net of forfeitures (in shares)			55,773
Share-based compensation expense, net of forfeitures	9,638		$ 1	9,637
Shares withheld for employee taxes (in shares)			(8,189)
Shares withheld for employee taxes	(927)			(927)
Conversion and redemption of OP units (in Shares)			749
Conversion and redemption of OP units	(5,906)		$ 0	(528)			(5,378)
Contributions from noncontrolling interests	3,924						3,924
Ending balance (in shares) at Sep. 30, 2018		405,896	73,859,280
Ending balance at Sep. 30, 2018	2,433,439	$ 159,997	$ 741	2,946,555	(795,649)	127	121,668
Beginning balance (in shares) at Jun. 30, 2018		405,896	73,434,943
Beginning balance at Jun. 30, 2018	2,387,592	$ 159,997	$ 737	2,884,771	(780,973)	412	122,648
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income, excluding amounts attributable to redeemable noncontrolling interests	63,258				62,558		700
Other comprehensive (loss) income - change in fair value of interest rate swaps	(285)					(285)
Dividends declared to common shareholders	(75,224)				(75,224)
Dividends declared to preferred shareholders	(2,010)				(2,010)
Distributions declared to noncontrolling interests	(1,243)						(1,243)
Shares issued (in shares)			464,113
Shares issued	59,051		$ 4					59,047
Exercise of stock options (in shares)			0
Exercise of stock options	0			0
Shares issued under dividend reinvestment plan (in shares)			4,458
Shares issued under dividend reinvestment plan	561			561
Share-based compensation expense, net of forfeitures (in shares)			(43,801)
Share-based compensation expense, net of forfeitures	2,494		$ 0	2,494
Shares withheld for employee taxes (in shares)			(1,182)
Shares withheld for employee taxes	(150)			(150)
Conversion and redemption of OP units (in Shares)			749
Conversion and redemption of OP units	(1,520)		$ 0	(168)			(1,352)
Contributions from noncontrolling interests	915						915
Ending balance (in shares) at Sep. 30, 2018		405,896	73,859,280
Ending balance at Sep. 30, 2018	2,433,439	$ 159,997	$ 741	2,946,555	(795,649)	127	121,668
Beginning balance (in shares) at Dec. 31, 2018		405,896	74,249,633
Beginning balance at Dec. 31, 2018	2,467,330	$ 159,997	$ 745	3,004,442	(818,877)	(416)	121,439
Increase (Decrease) in Stockholders' Equity [Roll Forward]
January 1 adoption of new accounting standard - See Note 2	(7,098)				(7,098)
Net income, excluding amounts attributable to redeemable noncontrolling interests	208,972				206,511		2,461
Other comprehensive (loss) income - change in fair value of interest rate swaps	(719)					(719)
Dividends declared to common shareholders	(231,657)				(231,657)
Dividends declared to preferred shareholders	(6,031)				(6,031)
Distributions declared to noncontrolling interests	(8,812)						(8,812)
Shares issued (in shares)			1,045,470
Shares issued	139,499		$ 11					139,488
Shares issued under dividend reinvestment plan (in shares)			12,006
Shares issued under dividend reinvestment plan	1,567			1,567
Share-based compensation expense, net of forfeitures (in shares)			110,804
Share-based compensation expense, net of forfeitures	10,143		$ 1	10,142
Shares withheld for employee taxes (in shares)			(34,234)
Shares withheld for employee taxes	(4,615)			(4,615)
Conversion and redemption of OP units (in Shares)			111,252
Conversion and redemption of OP units	(72)		$ 1	11,933			(12,006)
Contributions from noncontrolling interests	111						111
Adjustment to redeemable noncontrolling interests	4,503			4,503
Ending balance (in shares) at Sep. 30, 2019		405,896	75,494,931
Ending balance at Sep. 30, 2019	2,573,121	$ 159,997	$ 758	3,167,460	(857,152)	(1,135)	103,193
Beginning balance (in shares) at Jun. 30, 2019		405,896	74,950,197
Beginning balance at Jun. 30, 2019	2,510,646	$ 159,997	$ 752	3,088,946	(841,505)	(1,024)	103,480
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income, excluding amounts attributable to redeemable noncontrolling interests	66,285				65,465		820
Other comprehensive (loss) income - change in fair value of interest rate swaps	(111)					(111)
Dividends declared to common shareholders	(79,102)				(79,102)
Dividends declared to preferred shareholders	(2,010)				(2,010)
Distributions declared to noncontrolling interests	(1,148)						(1,148)
Shares issued (in shares)			533,516
Shares issued	71,195		$ 6					$ 71,189
Shares issued under dividend reinvestment plan (in shares)			3,885
Shares issued under dividend reinvestment plan	513			513
Share-based compensation expense, net of forfeitures (in shares)			8,667
Share-based compensation expense, net of forfeitures	3,151			3,151
Shares withheld for employee taxes (in shares)			(1,334)
Shares withheld for employee taxes	(173)			(173)
Conversion and redemption of OP units (in Shares)			0
Conversion and redemption of OP units	(72)			(2)			(70)
Contributions from noncontrolling interests	111						111
Adjustment to redeemable noncontrolling interests	3,836			3,836
Ending balance (in shares) at Sep. 30, 2019		405,896	75,494,931
Ending balance at Sep. 30, 2019	$ 2,573,121	$ 159,997	$ 758	$ 3,167,460	$ (857,152)	$ (1,135)	$ 103,193