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, 2015	$ 1,521,354	$ 70	$ 1,092,239	$ (4,463)	$ 12,642	$ 1,100,488	$ 420,866
Balance (in Shares) at Dec. 31, 2015		70,258,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0	$ 1	7,891			7,892	(7,892)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)		351,000
Issuance of Common Shares, net of issuance costs	450,130	$ 13	450,117			450,130
Issuance of Common Shares, net of issuance costs (in Shares)		12,961,000
Issuance of OP Units to acquire real estate	31,429						31,429
Dividends/distribution declared ($1.09, $1.05 and 1.16 per Common Share/OP Unit for Year Ended Dec 31, 2018, 2017 and 2016)	(97,806)				(91,053)	(91,053)	(6,753)
Employee and trustee stock compensation, net	13,694		926			926	12,768
Employee and trustee stock compensation, net (in Shares)		28,000
Windfall tax benefit	555		555			555
Change in control of previously unconsolidated investment	(75,713)						(75,713)
Acquisition of noncontrolling interest	(18,379)		7,546			7,546	(25,925)
Noncontrolling interest distributions	(80,769)						(80,769)
Noncontrolling interest contributions	295,108						295,108
Comprehensive (loss) income	138,522			3,665	72,776	76,441	62,081
Reallocation of noncontrolling interests	0		35,652			35,652	(35,652)
Ending 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
Repurchase of Common Shares (in shares)	0
Dividends/distribution declared ($1.09, $1.05 and 1.16 per Common Share/OP Unit for Year Ended Dec 31, 2018, 2017 and 2016)	$ (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	83,708,140	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/distribution declared ($1.09, $1.05 and 1.16 per Common Share/OP Unit for Year Ended Dec 31, 2018, 2017 and 2016)	$ (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