Consolidated Statement of Equity - USD ($) $ in Thousands	Total	Total Shareholders’  Equity	Par Value	Additional Paid in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Total Noncontrolling Interests	Operating Partnership Noncontrolling Interest	Partially Owned Properties Noncontrolling Interest
Balance at beginning of period at Dec. 31, 2021	$ 2,987,033	$ 2,836,308	$ 2,247	$ 3,610,954	$ (776,001)	$ (892)	$ 150,725	$ 150,241	$ 484
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net proceeds from sale of common shares	5,032	5,032	3	5,029
Restricted share award grants, net	(300)	(300)	3	118	(421)
Purchase of OP Units	(184)						(184)	(184)
Dividends/distributions declared	(54,619)	(51,879)			(51,879)		(2,740)	(2,740)
Contributions	569						569		569
Distributions	(55)						(55)		(55)
Change in market value of Redeemable Noncontrolling Interest in partially owned properties	717	717			717
Change in fair value of interest rate swap agreements	1,379	1,379				1,379
Adjustment for Noncontrolling Interests ownership in Operating Partnership	0	(217)		(217)			217	217
Net income	13,866	13,092			13,092		774	692	82
Balance at end of period at Mar. 31, 2022	2,953,438	2,804,132	2,253	3,615,884	(814,492)	487	149,306	148,226	1,080
Balance at beginning of period at Dec. 31, 2021	2,987,033	2,836,308	2,247	3,610,954	(776,001)	(892)	150,725	150,241	484
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in fair value of interest rate swap agreements	4,462
Balance at end of period at Jun. 30, 2022	2,941,177	2,793,191	2,263	3,637,459	(850,101)	3,570	147,986	146,888	1,098
Balance at beginning of period at Mar. 31, 2022	2,953,438	2,804,132	2,253	3,615,884	(814,492)	487	149,306	148,226	1,080
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net proceeds from sale of common shares	18,484	18,484	9	18,475
Restricted share award grants, net	2,678	2,678	1	3,588	(911)
Dividends/distributions declared	(54,828)	(52,116)			(52,116)		(2,712)	(2,712)
Distributions	(61)						(61)		(61)
Change in market value of Redeemable Noncontrolling Interest in partially owned properties	527	527			527
Change in fair value of interest rate swap agreements	3,083	3,083				3,083
Adjustment for Noncontrolling Interests ownership in Operating Partnership	0	(488)		(488)			488	488
Net income	17,856	16,891			16,891		965	886	79
Balance at end of period at Jun. 30, 2022	2,941,177	2,793,191	2,263	3,637,459	(850,101)	3,570	147,986	146,888	1,098
Balance at beginning of period at Dec. 31, 2022	2,993,851	2,869,720	2,333	3,743,876	(881,672)	5,183	124,131	123,015	1,116
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net proceeds from sale of common shares	65,813	65,813	44	65,769
Restricted share award grants, net	(1,530)	(1,530)	5	(1,127)	(408)
Conversion of OP Units	0	2,419	2	2,417			(2,419)	(2,419)
Dividends/distributions declared	(57,175)	(54,912)			(54,912)		(2,263)	(2,263)
Contributions	7,884						7,884		7,884
Distributions	(53)						(53)		(53)
Change in fair value of interest rate swap agreements	(1,021)	(1,021)				(1,021)
Adjustment for Noncontrolling Interests ownership in Operating Partnership	0	(431)		(431)			431	431
Net income	10,689	10,202			10,202		487	423	64
Balance at end of period at Mar. 31, 2023	3,018,458	2,890,260	2,384	3,810,504	(926,790)	4,162	128,198	119,187	9,011
Balance at beginning of period at Dec. 31, 2022	2,993,851	2,869,720	2,333	3,743,876	(881,672)	5,183	124,131	123,015	1,116
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Change in fair value of interest rate swap agreements	4,099
Balance at end of period at Jun. 30, 2023	2,982,859	2,855,788	2,385	3,813,864	(969,743)	9,282	127,071	117,766	9,305
Balance at beginning of period at Mar. 31, 2023	3,018,458	2,890,260	2,384	3,810,504	(926,790)	4,162	128,198	119,187	9,011
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net proceeds from sale of common shares	294	294		294
Restricted share award grants, net	2,899	2,899	1	3,459	(561)
Purchase of OP Units	(72)						(72)	(72)
Dividends/distributions declared	(57,193)	(54,936)			(54,936)		(2,257)	(2,257)
Contributions	287						287		287
Distributions	(52)						(52)		(52)
Change in fair value of interest rate swap agreements	5,120	5,120				5,120
Adjustment for Noncontrolling Interests ownership in Operating Partnership	0	(393)		(393)			393	393
Net income	13,118	12,544			12,544		574	515	59
Balance at end of period at Jun. 30, 2023	$ 2,982,859	$ 2,855,788	$ 2,385	$ 3,813,864	$ (969,743)	$ 9,282	$ 127,071	$ 117,766	$ 9,305