CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Total Shareholders’ Equity	Common Shares	Additional Paid-In Capital	Accumulated Other Comprehensive (Loss) Income	Retained Earnings	Noncontrolling Interests
Balance at Dec. 31, 2014	$ 1,435,957	$ 1,055,541	$ 68	$ 1,027,861	$ (4,005)	$ 31,617	$ 380,416
Balance (in Shares) at Dec. 31, 2014	68,109,287		68,109
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)			44
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership	0	1,094		1,094			(1,094)
Issuance of Common Shares, net of issuance costs (in Shares)			571
Issuance of Common Shares, net of issuance costs	19,333	19,333	1	19,332
Dividends declared ($0.24 per Common Share)	(17,672)	(16,486)				(16,486)	(1,186)
Vesting of employee Restricted Share and LTIP awards (in Shares)			8
Employee and trustee stock compensation, net	1,878	170		170			1,708
Noncontrolling interest distributions	(33,089)						(33,089)
Noncontrolling interest contributions	50						50
Balance before adjustment towards comprehensive income (in Shares)			68,732
Balance before adjustment towards comprehensive income	1,406,457	1,059,652	69	1,048,457	(4,005)	15,131	346,805
Comprehensive (loss) income:
Net income	38,537	16,547				16,547	21,990
Unrealized loss on valuation of swap agreements	(4,319)	(3,536)			(3,536)		(783)
Reclassification of realized interest on swap agreements	1,053	693			693		360
Comprehensive income	35,271	13,704			(2,843)	16,547	21,567
Balance at Mar. 31, 2015	$ 1,441,728	$ 1,073,356	$ 69	$ 1,048,457	$ (6,848)	$ 31,678	$ 368,372
Balance (in Shares) at Mar. 31, 2015	68,731,681		68,732