CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands		Total	Common Shares	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	(Distributions in Excess of Accumulated Earnings) Retained Earnings	Total Common Shareholders’ Equity	Noncontrolling Interests
Balance at Dec. 31, 2013		$ 1,121,588	$ 56	$ 665,301	$ 1,132	$ 37,747	$ 704,236	$ 417,352
Balance (in Shares) at Dec. 31, 2013			55,643,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership		0		3,181			3,181	(3,181)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)			136,000
Issuance of Common Shares, net of issuance costs		357,459	$ 12	357,447			357,459
Issuance of Common Shares, net of issuance costs (in Shares)			12,237,000
Issuance of OP Units to acquire real estate		44,051						44,051
Dividends declared	[1]	(82,279)				(77,194)	(77,194)	(5,085)
Employee and trustee stock compensation, net		8,460		1,932			1,932	6,528
Employee and trustee stock compensation, net (in Shares)			93,000
Noncontrolling interest distributions		(218,152)						(218,152)
Noncontrolling interest contributions		57,969						57,969
Comprehensive (loss) income		146,861			(5,137)	71,064	65,927	80,934
Balance at Dec. 31, 2014		1,435,957	$ 68	1,027,861	(4,005)	31,617	1,055,541	380,416
Balance (in Shares) at Dec. 31, 2014			68,109,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership		0		2,451			2,451	(2,451)
Conversion of OP Units to Common Shares by limited partners of the Operating Partnership (in Shares)			101,000
Issuance of Common Shares, net of issuance costs		64,417	$ 2	64,415			64,417
Issuance of Common Shares, net of issuance costs (in Shares)			1,973,000
Issuance of OP Units to acquire real estate		0
Dividends declared	[2]	(90,666)				(84,683)	(84,683)	(5,983)
Acquisition of noncontrolling interests		(7,970)		(4,409)			(4,409)	(3,561)
Employee and trustee stock compensation, net		8,644		1,921			1,921	6,723
Employee and trustee stock compensation, net (in Shares)			75,000
Noncontrolling interest distributions		(74,950)						(74,950)
Noncontrolling interest contributions		35,489						35,489
Comprehensive (loss) income		150,433			(458)	65,708	65,250	85,183
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		70,258,415	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		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 declared	[3]	(97,806)				(91,053)	(91,053)	(6,753)
Change in control of previously unconsolidated investment		(75,713)						(75,713)
Windfall tax benefit		555		555			555
Acquisition of noncontrolling interests		(18,379)		7,546			7,546	(25,925)
Employee and trustee stock compensation, net		13,694		926			926	12,768
Employee and trustee stock compensation, net (in Shares)			28,000
Noncontrolling interest distributions		(80,769)						(80,769)
Noncontrolling interest contributions		295,108						295,108
Reallocation of noncontrolling interests		0		35,652			35,652	(35,652)
Comprehensive (loss) income		138,522			3,665	72,776	76,441	62,081
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		83,597,741	83,598,000

[1] Includes a special dividend of $0.30 announced on December 5, 2014 and paid on January 15, 2015.

[2] Includes a special dividend of $0.25 declared on November 10, 2015 and paid on January 15, 2016.

[3] Includes a special cash dividend of $0.15 declared on November 8, 2016 and paid on January 13, 2017 (Note 10).