CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Shares	Additional Paid-in Capital	AOCI Attributable to Parent	Retained Earnings	Parent	Noncontrolling Interests
Beginning 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		1,123			1,123	(1,123)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		64,000
Repurchase of Common Shares	(55,057)	$ (2)	(55,055)			(55,057)
Repurchase of Common Shares (in shares)		(2,294,000)
Dividends/distributions declared ($0.28, $0.27, $0.56 and $0.57 per Common Share/OP Unit for three months and six months ended june 30, 2019 and 2018)	(47,701)				(44,267)	(44,267)	(3,434)
Employee and trustee stock compensation, net	6,113		271			271	5,842
Employee and trustee stock compensation, net (in Shares)		25,000
Noncontrolling interest distributions	(15,640)						(15,640)
Noncontrolling interest contributions	6,550						6,550
Comprehensive (loss) income	2,645			7,524	15,084	22,608	(19,963)
Reallocation of noncontrolling interests	0		798			798	(798)
Ending Balance at Jun. 30, 2018	2,112,549	$ 82	1,543,651	10,138	(61,196)	1,492,675	619,874
Balance (in Shares) at Jun. 30, 2018		81,503,000
Beginning 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]
Repurchase of Common Shares	$ (55,100)
Repurchase of Common Shares (in shares)	(2,294,235)
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
Beginning Balance at Mar. 31, 2018	$ 2,164,667	$ 82	1,564,067	7,376	(46,856)	1,524,669	639,998
Balance (in Shares) at Mar. 31, 2018		82,451,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0		481			481	(481)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		28,000
Repurchase of Common Shares	(23,095)		(23,095)			(23,095)
Repurchase of Common Shares (in shares)		(990,000)
Dividends/distributions declared ($0.28, $0.27, $0.56 and $0.57 per Common Share/OP Unit for three months and six months ended june 30, 2019 and 2018)	(23,718)				(22,005)	(22,005)	(1,713)
Employee and trustee stock compensation, net	2,301		175			175	2,126
Employee and trustee stock compensation, net (in Shares)		14,000
Noncontrolling interest distributions	(14,945)						(14,945)
Noncontrolling interest contributions	6,550						6,550
Comprehensive (loss) income	789			2,762	7,665	10,427	(9,638)
Reallocation of noncontrolling interests	0		2,023			2,023	(2,023)
Ending Balance at Jun. 30, 2018	2,112,549	$ 82	1,543,651	10,138	(61,196)	1,492,675	619,874
Balance (in Shares) at Jun. 30, 2018		81,503,000
Beginning 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		3,510			3,510	(3,510)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		208,000
Repurchase of Common Shares (in shares)	0
Issuance of Common Shares	$ 75,115	$ 2	75,113			75,115
Issuance of Common Shares (in Shares)		2,667,000
Dividends/distributions declared ($0.28, $0.27, $0.56 and $0.57 per Common Share/OP Unit for three months and six months ended june 30, 2019 and 2018)	(50,362)				(46,805)	(46,805)	(3,557)
Employee and trustee stock compensation, net	5,442		247			247	5,195
Employee and trustee stock compensation, net (in Shares)		21,000
Noncontrolling interest distributions	(4,882)						(4,882)
Noncontrolling interest contributions	32,191						32,191
Comprehensive (loss) income	(39,345)			(30,086)	21,277	(8,809)	(30,536)
Reallocation of noncontrolling interests	0		(1,567)			(1,567)	1,567
Ending Balance at Jun. 30, 2019	$ 2,100,106	$ 84	1,625,906	(29,570)	(115,224)	1,481,196	618,910
Balance (in Shares) at Jun. 30, 2019	84,452,945	84,453,000
Beginning Balance at Mar. 31, 2019	$ 2,106,352	$ 83	1,577,503	(11,021)	(100,634)	1,465,931	640,421
Balance (in Shares) at Mar. 31, 2019		82,708,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0		557			557	(557)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		33,000
Issuance of Common Shares	47,281	$ 1	47,280			47,281
Issuance of Common Shares (in Shares)		1,697,000
Dividends/distributions declared ($0.28, $0.27, $0.56 and $0.57 per Common Share/OP Unit for three months and six months ended june 30, 2019 and 2018)	(25,446)				(23,670)	(23,670)	(1,776)
Employee and trustee stock compensation, net	1,988		153			153	1,835
Employee and trustee stock compensation, net (in Shares)		15,000
Noncontrolling interest distributions	(1,645)						(1,645)
Comprehensive (loss) income	(28,424)			(18,549)	9,080	(9,469)	(18,955)
Reallocation of noncontrolling interests	0		413			413	(413)
Ending Balance at Jun. 30, 2019	$ 2,100,106	$ 84	$ 1,625,906	$ (29,570)	$ (115,224)	$ 1,481,196	$ 618,910
Balance (in Shares) at Jun. 30, 2019	84,452,945	84,453,000