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	126,466				124,842		1,624
Other comprehensive (loss) income - change in fair value of interest rate swaps	390					390
Dividends declared to common shareholders	(146,399)				(146,399)
Dividends declared to preferred shareholders	(4,021)				(4,021)
Distributions declared to noncontrolling interests	(2,767)						(2,767)
Shares issued (in shares)			148,614
Shares issued	18,320		$ 2					$ 18,318
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)			9,292
Shares issued under dividend reinvestment plan	1,086			1,086
Share-based compensation expense, net of forfeitures (in shares)			99,574
Share-based compensation expense, net of forfeitures	7,144		$ 1	7,143
Shares withheld for employee taxes (in shares)			(7,007)
Shares withheld for employee taxes	(777)			(777)
Conversion and redemption of OP units (in Shares)			0
Conversion and redemption of OP units	(4,386)		$ 0	(360)			(4,026)
Contributions from noncontrolling interests	3,009						3,009
Ending balance (in shares) at Jun. 30, 2018		405,896	73,434,943
Ending balance at Jun. 30, 2018	2,387,592	$ 159,997	$ 737	2,884,771	(780,973)	412	122,648
Beginning balance (in shares) at Mar. 31, 2018		405,896	73,216,520
Beginning balance at Mar. 31, 2018	2,373,110	$ 159,997	$ 735	2,859,717	(769,311)	489	121,483
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income, excluding amounts attributable to redeemable noncontrolling interests	64,550				63,595		955
Other comprehensive (loss) income - change in fair value of interest rate swaps	(77)					(77)
Dividends declared to common shareholders	(73,246)				(73,246)
Dividends declared to preferred shareholders	(2,011)				(2,011)
Distributions declared to noncontrolling interests	(1,419)						(1,419)
Shares issued (in shares)			148,584
Shares issued	18,316		$ 2					18,314
Exercise of stock options (in shares)			63,593
Exercise of stock options	2,779			2,779
Shares issued under dividend reinvestment plan (in shares)			4,852
Shares issued under dividend reinvestment plan	539			539
Share-based compensation expense, net of forfeitures (in shares)			1,606
Share-based compensation expense, net of forfeitures	3,274		$ 0	3,274
Shares withheld for employee taxes (in shares)			(212)
Shares withheld for employee taxes	(24)			(24)
Conversion and redemption of OP units (in Shares)			0
Conversion and redemption of OP units	(1,208)		$ 0	172			(1,380)
Contributions from noncontrolling interests	3,009						3,009
Ending balance (in shares) at Jun. 30, 2018		405,896	73,434,943
Ending balance at Jun. 30, 2018	2,387,592	$ 159,997	$ 737	2,884,771	(780,973)	412	122,648
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	142,687				141,046		1,641
Other comprehensive (loss) income - change in fair value of interest rate swaps	(608)					(608)
Dividends declared to common shareholders	(152,555)				(152,555)
Dividends declared to preferred shareholders	(4,021)				(4,021)
Distributions declared to noncontrolling interests	(7,664)						(7,664)
Shares issued (in shares)			511,954
Shares issued	68,304		$ 5					68,299
Shares issued under dividend reinvestment plan (in shares)			8,121
Shares issued under dividend reinvestment plan	1,054			1,054
Share-based compensation expense, net of forfeitures (in shares)			102,137
Share-based compensation expense, net of forfeitures	6,992		$ 1	6,991
Shares withheld for employee taxes (in shares)			(32,900)
Shares withheld for employee taxes	(4,442)			(4,442)
Conversion and redemption of OP units (in Shares)			111,252
Conversion and redemption of OP units	0		$ 1	11,935			(11,936)
Adjustment to redeemable noncontrolling interests	667			667
Ending balance (in shares) at Jun. 30, 2019		405,896	74,950,197
Ending balance at Jun. 30, 2019	2,510,646	$ 159,997	$ 752	3,088,946	(841,505)	(1,024)	103,480
Beginning balance (in shares) at Mar. 31, 2019		405,896	74,836,984
Beginning balance at Mar. 31, 2019	2,501,563	$ 159,997	$ 752	3,071,981	(843,947)	(625)	113,405
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income, excluding amounts attributable to redeemable noncontrolling interests	81,760				80,902		858
Other comprehensive (loss) income - change in fair value of interest rate swaps	(399)					(399)
Dividends declared to common shareholders	(76,449)				(76,449)
Dividends declared to preferred shareholders	(2,011)				2,011
Distributions declared to noncontrolling interests	(6,398)						6,398
Shares issued (in shares)			65,822
Shares issued	8,951		$ 0					$ 8,951
Shares issued under dividend reinvestment plan (in shares)			3,848
Shares issued under dividend reinvestment plan	526			526
Share-based compensation expense, net of forfeitures (in shares)			1,551
Share-based compensation expense, net of forfeitures	3,131			3,131
Shares withheld for employee taxes (in shares)			(214)
Shares withheld for employee taxes	(28)			(28)
Conversion and redemption of OP units (in Shares)			42,206
Conversion and redemption of OP units	0			4,385			(4,385)
Ending balance (in shares) at Jun. 30, 2019		405,896	74,950,197
Ending balance at Jun. 30, 2019	$ 2,510,646	$ 159,997	$ 752	$ 3,088,946	$ (841,505)	$ (1,024)	$ 103,480