CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - 6 months ended Jun. 30, 2015 - 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, 2014	68,109,287		68,109,000
Balance at Dec. 31, 2014	$ 1,435,957	$ 1,055,541	$ 68	$ 1,027,861	$ (4,005)	$ 31,617	$ 380,416
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)			67,000
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0	1,655		1,655			(1,655)
Issuance of Common Shares, net of issuance costs (in Shares)			624,000
Issuance of Common Shares, net of issuance costs	21,080	21,080	$ 1	21,079
Dividends declared ($0.48 per Common Share)	(35,368)	(33,005)				(33,005)	(2,363)
Employee and trustee stock compensation, net (in Shares)			29,000
Employee and trustee stock compensation, net	3,844	452		452			3,392
Acquisition of noncontrolling interests	(662)
Noncontrolling interest distributions	(60,907)						(60,907)
Noncontrolling interest contributions	30,134						30,134
Balance before adjustment towards comprehensive income (in Shares)			68,829,000
Balance before adjustment towards comprehensive income	1,394,078	1,045,061	$ 69	1,050,385	(4,005)	(1,388)	349,017
Comprehensive (loss) income:
Net income	123,995	43,042				43,042	80,953
Unrealized loss on valuation of swap agreements	(1,655)	(1,097)			(1,097)		(558)
Reclassification of realized interest on swap agreements	3,452	1,818			1,818		1,634
Total comprehensive income	$ 125,792	43,763			721	43,042	82,029
Balance (in Shares) at Jun. 30, 2015	68,828,560		68,829,000
Balance at Jun. 30, 2015	$ 1,519,870	$ 1,088,824	$ 69	$ 1,050,385	$ (3,284)	$ 41,654	$ 431,046