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		1,957			1,957	(1,957)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		111,000
Repurchase of Common Shares	$ (55,057)	$ (2)	(55,055)			(55,057)
Repurchase of Common Shares (in shares)	(2,294,235)	(2,294,000)
Dividends/distributions declared ($0.28, $0.27, $0.84 and $0.81 per Common Share/OP Unit for three months and nine months ended September 30, 2019 and 2018)	$ (71,412)				(66,286)	(66,286)	(5,126)
Employee and trustee stock compensation, net	8,332		408			408	7,924
Employee and trustee stock compensation, net (in Shares)		25,000
Noncontrolling interest distributions	(24,654)						(24,654)
Noncontrolling interest contributions	46,990						46,990
Comprehensive (loss) income	3,966			10,653	24,309	34,962	(30,996)
Reallocation of noncontrolling interests	0		2,581			2,581	(2,581)
Ending Balance at Sep. 30, 2018	2,123,804	$ 82	1,546,405	13,267	(73,990)	1,485,764	638,040
Balance (in Shares) at Sep. 30, 2018		81,550,000
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 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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0		834			834	(834)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		47,000
Dividends/distributions declared ($0.28, $0.27, $0.84 and $0.81 per Common Share/OP Unit for three months and nine months ended September 30, 2019 and 2018)	(23,711)				(22,019)	(22,019)	(1,692)
Employee and trustee stock compensation, net	2,219		137			137	2,082
Noncontrolling interest distributions	(9,014)						(9,014)
Noncontrolling interest contributions	40,440						40,440
Comprehensive (loss) income	1,321			3,129	9,225	12,354	(11,033)
Reallocation of noncontrolling interests	0		1,783			1,783	(1,783)
Ending Balance at Sep. 30, 2018	2,123,804	$ 82	1,546,405	13,267	(73,990)	1,485,764	638,040
Balance (in Shares) at Sep. 30, 2018		81,550,000
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		4,230			4,230	(4,230)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		250,000
Repurchase of Common Shares (in shares)	0
Issuance of Common Shares	$ 135,751	$ 5	135,746			135,751
Issuance of Common Shares (in Shares)		4,816,000
Dividends/distributions declared ($0.28, $0.27, $0.84 and $0.81 per Common Share/OP Unit for three months and nine months ended September 30, 2019 and 2018)	(76,387)				(71,065)	(71,065)	(5,322)
Employee and trustee stock compensation, net	7,361		396			396	6,965
Employee and trustee stock compensation, net (in Shares)		21,000
Noncontrolling interest distributions	(34,595)						(34,595)
Noncontrolling interest contributions	161,628						161,628
Comprehensive (loss) income	(46,182)			(44,654)	31,735	(12,919)	(33,263)
Reallocation of noncontrolling interests	0		3,684			3,684	(3,684)
Ending Balance at Sep. 30, 2019	$ 2,229,523	$ 87	1,692,659	(44,138)	(129,026)	1,519,582	709,941
Balance (in Shares) at Sep. 30, 2019	86,644,196	86,644,000
Beginning 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		84,453,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0		720			720	(720)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		42,000
Issuance of Common Shares	60,637	$ 3	60,634			60,637
Issuance of Common Shares (in Shares)		2,149,000
Dividends/distributions declared ($0.28, $0.27, $0.84 and $0.81 per Common Share/OP Unit for three months and nine months ended September 30, 2019 and 2018)	(26,025)				(24,260)	(24,260)	(1,765)
Employee and trustee stock compensation, net	1,916		148			148	1,768
Noncontrolling interest distributions	(29,713)						(29,713)
Noncontrolling interest contributions	129,438						129,438
Comprehensive (loss) income	(6,836)			(14,568)	10,458	(4,110)	(2,726)
Reallocation of noncontrolling interests	0		5,251			5,251	(5,251)
Ending Balance at Sep. 30, 2019	$ 2,229,523	$ 87	$ 1,692,659	$ (44,138)	$ (129,026)	$ 1,519,582	$ 709,941
Balance (in Shares) at Sep. 30, 2019	86,644,196	86,644,000