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 Income/(Loss)	Noncontrolling Interests	Common shares	Preferred Shares	Preferred Shares Additional Paid-in Capital
Beginning balance (in shares) at Dec. 31, 2016		399,896	71,995,897
Beginning balance at Dec. 31, 2016	$ 2,075,835	$ 9,997	$ 722	$ 2,718,325	$ (749,734)	$ (2,577)	$ 99,102
Increase (Decrease) in Stockholders' Equity [Roll Forward]
January 1 adoption of new accounting standard - See Note 2	0			83	(83)
Net income, excluding amount attributable to redeemable noncontrolling interests	293,996				289,914		4,082
Other comprehensive (loss) income - change in value of interest rate swaps	2,599					2,599
Dividends declared to common shareholders	(287,006)				(287,006)
Dividends declared to preferred shareholders	(2,458)				(2,458)
Distributions declared to noncontrolling interests	(5,560)						(5,560)
Shares issued (in shares)		6,000	826,592
Shares issued		$ 150,000	$ 8	108,240				$ 108,248	$ 144,965	$ (5,035)
Exercise of stock options (in shares)			152,634
Exercise of stock options	$ 9,979		$ 2	9,977
Shares issued under dividend reinvestment plan (in shares)	17,911		17,911
Shares issued under dividend reinvestment plan	$ 2,373			2,373
Share-based compensation expense, net of forfeitures (in shares)			107,522
Share-based compensation expense, net of forfeitures	12,371		$ 1	12,370
Shares withheld for employee taxes (in shares)			(29,709)
Shares withheld for employee taxes	(4,229)			(4,229)
Conversion and redemption of OP units (in shares)			20,030
Conversion and redemption of OP units	0		$ 0	2,569			(2,569)
Purchase of noncontrolling interests	(5,536)			42			(5,578)
Contributions from noncontrolling interests	35,331						35,331
Adjustment to redeemable noncontrolling interests	10,606			10,606
Ending balance (in shares) at Dec. 31, 2017		405,896	73,090,877
Ending 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 amount attributable to redeemable noncontrolling interests	245,161				241,907		3,254
Other comprehensive (loss) income - change in value of interest rate swaps	(438)					(438)
Dividends declared to common shareholders	(297,347)				(297,347)
Dividends declared to preferred shareholders	(8,042)				(8,042)
Distributions declared to noncontrolling interests	(5,175)						(5,175)
Shares issued (in shares)			987,461
Shares issued	126,071		$ 10	126,061
Exercise of stock options (in shares)			105,803
Exercise of stock options	$ 4,572		$ 1	4,571
Shares issued under dividend reinvestment plan (in shares)	17,952		17,952
Shares issued under dividend reinvestment plan	$ 2,159			2,159
Share-based compensation expense, net of forfeitures (in shares)			55,223
Share-based compensation expense, net of forfeitures	12,736		$ 1	12,735
Shares withheld for employee taxes (in shares)			(8,432)
Shares withheld for employee taxes	(958)			(958)
Conversion and redemption of OP units (in shares)			749
Conversion and redemption of OP units	(6,012)		$ 0	(544)			(5,468)
Contributions from noncontrolling interests	4,020						4,020
Adjustment to redeemable noncontrolling interests	5,097			5,097
Ending balance (in shares) at Dec. 31, 2018		405,896	74,249,633
Ending 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 amount attributable to redeemable noncontrolling interests	357,112				353,866		3,246
Other comprehensive (loss) income - change in value of interest rate swaps	(397)					(397)
Dividends declared to common shareholders	(310,973)				(310,973)
Dividends declared to preferred shareholders	(8,042)				(8,042)
Distributions declared to noncontrolling interests	(9,961)						(9,961)
Shares issued (in shares)			1,069,740
Shares issued	$ 142,716		$ 11	142,705
Exercise of stock options (in shares)	0
Shares issued under dividend reinvestment plan (in shares)	15,909		15,909
Shares issued under dividend reinvestment plan	$ 2,095			2,095
Share-based compensation expense, net of forfeitures (in shares)			111,555
Share-based compensation expense, net of forfeitures	13,330		$ 1	13,329
Shares withheld for employee taxes (in shares)			(34,320)
Shares withheld for employee taxes	(4,626)			(4,626)
Conversion and redemption of OP units (in shares)			128,287
Conversion and redemption of OP units	(72)		$ 2	14,102			(14,176)
Contributions from noncontrolling interests	243						243
Adjustment to redeemable noncontrolling interests	(5,525)			(5,525)
Ending balance (in shares) at Dec. 31, 2019		405,896	75,540,804
Ending balance at Dec. 31, 2019	$ 2,636,132	$ 159,997	$ 759	$ 3,166,522	$ (791,124)	$ (813)	$ 100,791