CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Shares	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Distributions in Excess of Accumulated Earnings	Total Common Shareholders? Equity	Noncontrolling Interests
Beginning Balance at Dec. 31, 2016	$ 2,178,125	$ 84	$ 1,594,926	$ (798)	$ (5,635)	$ 1,588,577	$ 589,548
Balance (in Shares) at Dec. 31, 2016		83,598,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0		1,541			1,541	(1,541)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		87,000
Dividends/distributions declared ($1.13, $1.09 and 1.05 per Common Share/OP Unit for Year Ended Dec 31, 2019, 2018 and 2017)	(94,301)				(87,848)	(87,848)	(6,453)
Employee and trustee stock compensation, net	11,155		698			698	10,457
Employee and trustee stock compensation, net (in Shares)		23,000
Noncontrolling interest distributions	(32,805)						(32,805)
Noncontrolling interest contributions	85,206						85,206
Comprehensive (loss) income	68,259			3,412	61,470	64,882	3,377
Reallocation of noncontrolling interests	0		(651)			(651)	651
Ending Balance at Dec. 31, 2017	2,215,639	$ 84	1,596,514	2,614	(32,013)	1,567,199	648,440
Balance (in Shares) at Dec. 31, 2017		83,708,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0		2,068			2,068	(2,068)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		117,000
Repurchase of Common Shares	$ (55,111)	$ (2)	(55,109)			(55,111)
Repurchase of Common Shares (in shares)	(2,294,235)	(2,294,000)
Dividends/distributions declared ($1.13, $1.09 and 1.05 per Common Share/OP Unit for Year Ended Dec 31, 2019, 2018 and 2017)	$ (96,010)				(89,122)	(89,122)	(6,888)
Employee and trustee stock compensation, net	12,948		574			574	12,374
Employee and trustee stock compensation, net (in Shares)		26,000
Noncontrolling interest distributions	(24,793)						(24,793)
Noncontrolling interest contributions	47,560						47,560
Comprehensive (loss) income	(18,286)			(2,098)	31,439	29,341	(47,627)
Reallocation of noncontrolling interests	0		4,556			4,556	(4,556)
Ending Balance at Dec. 31, 2018	$ 2,081,947	$ 82	1,548,603	516	(89,696)	1,459,505	622,442
Balance (in Shares) at Dec. 31, 2018	81,557,472	81,557,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	$ 0		5,104			5,104	(5,104)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		308,000
Repurchase of Common Shares (in shares)	0
Issuance of Common Shares	$ 145,498	$ 5	145,493			145,498
Issuance of Common Shares		5,164,000
Dividends/distributions declared ($1.13, $1.09 and 1.05 per Common Share/OP Unit for Year Ended Dec 31, 2019, 2018 and 2017)	(103,434)				(96,310)	(96,310)	(7,124)
Employee and trustee stock compensation, net	10,957		546			546	10,411
Employee and trustee stock compensation, net (in Shares)		21,000
Noncontrolling interest distributions	(94,289)						(94,289)
Noncontrolling interest contributions	161,628						161,628
Comprehensive (loss) income	(15,342)			(31,691)	53,045	21,354	(36,696)
Reallocation of noncontrolling interests	0		6,611			6,611	(6,611)
Ending Balance at Dec. 31, 2019	$ 2,186,965	$ 87	$ 1,706,357	$ (31,175)	$ (132,961)	$ 1,542,308	$ 644,657
Balance (in Shares) at Dec. 31, 2019	87,050,465	87,050,000