CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - 6 months ended Jun. 30, 2016 - USD ($) $ in Thousands	Total	Total Shareholders’ Equity	Common Shares	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss) Income	Retained Earnings	Noncontrolling Interests
Balance (in Shares) at Dec. 31, 2015	70,258,415		70,258,000
Balance at period start at Dec. 31, 2015	$ 1,521,354	$ 1,100,488	$ 70	$ 1,092,239	$ (4,463)	$ 12,642	$ 420,866
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)			319,000
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0	7,383	$ 1	7,382			(7,383)
Issuance of Common Shares, net of issuance costs (in Shares)			4,170,000
Issuance of Common Shares, net of issuance costs	141,349	141,349	$ 4	141,345
Issuance of OP Units to Acquire Real Estate	29,336						29,336
Dividends declared ($0.50 per Common Share)	(39,498)	(36,566)				(36,566)	(2,932)
Employee and trustee stock compensation, net (in Shares)			26,000
Employee and trustee stock compensation, net	6,076	474		474			5,602
Acquisition of noncontrolling interests	(18,379)	7,569		7,569			(25,948)
Change in control of previously consolidated investment	(75,713)						(75,713)
Noncontrolling interest distributions	(49,135)						(49,135)
Noncontrolling interest contributions	157,409						157,409
Reallocation of noncontrolling interest	0	38,845		38,845			(38,845)
Balance before adjustment towards comprehensive income (in Shares)			74,773,000
Balance before adjustment towards comprehensive income	1,672,799	1,259,542	$ 75	1,287,854	(4,463)	(23,924)	413,257
Comprehensive (loss) income:
Net income	100,030	46,843				46,843	53,187
Unrealized loss on valuation of swap agreements	(14,098)	(12,656)			(12,656)		(1,442)
Reclassification of realized interest on swap agreements	2,186	1,899			1,899		287
Comprehensive income	$ 88,118	36,086			(10,757)	46,843	52,032
Balance (in Shares) at Jun. 30, 2016	74,772,581		74,773,000
Balance at period end at Jun. 30, 2016	$ 1,760,917	$ 1,295,628	$ 75	$ 1,287,854	$ (15,220)	$ 22,919	$ 465,289