Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014		Jun. 30, 2015		Jun. 30, 2014
Net increase (decrease) in shareholders' equity resulting from operations
Net Income (Loss) Attributable to Parent		$ 13,152	$ 20,947	[1]	$ 32,413		$ 43,582	[1]
Net Income (Loss) Attributable to Participating Non-controlling Interest	[2]	82	172		202		357
Net income (loss) attributable to parent and participating non-controlling interest		13,234	21,119		32,615		43,939
Net increase in shareholders' equity resulting from operations– common shares		12,985	20,614		32,002		42,889
Net increase in shareholders' equity resulting from operations– LTIP units		167	333		411		693
Dividends Paid(2):
Common shareholders	[3]	(21,742)	(19,590)		(43,486)		(39,180)
LTIP unit holders	[3]	(279)	(317)		(558)		(633)
Non-controlling Interest	[3]	(138)	(163)		(274)		(327)
Total dividends paid to common shareholders, LTIP unit holders, and non-controlling interest	[3]	(22,159)	(20,070)		(44,318)	[4]	(40,140)	[4]
Undistributed (Distributed in excess of) earnings:
Common shareholders		(8,757)	1,024		(11,484)		3,709
LTIP unit holders		(112)	16		(147)		60
Non-controlling interest		(56)	9		(72)		30
Total undistributed (distributed in excess of) earnings attributable to common shareholders, LTIP unit holders, and non-controlling interest		$ (8,925)	$ 1,049		$ (11,703)		$ 3,799
Weighted average shares outstanding (basic and diluted):
Weighted average common shares outstanding		33,449,678	25,441,750		33,449,678		25,438,677
Weighted average participating LTIP units		429,314	411,052		429,314		411,052
Weighted average non-controlling interest units		212,000	212,000		212,000		212,000
Basic earnings per common share:
Distributed (in usd per share)		$ 0.65	$ 0.77		$ 1.30		$ 1.54
Undistributed (Distributed in excess of) (in usd per share)		(0.26)	0.04		(0.34)		0.15
Basic earnings per common share (in usd per share)		0.39	0.81		0.96		1.69
Diluted earnings per common share:
Distributed (in usd per share)		0.65	0.77		1.30		1.54
Undistributed (Distributed in excess of) (in usd per share)		(0.26)	0.04		(0.34)		0.15
Diluted earnings per common share (in usd per share)		$ 0.39	$ 0.81		$ 0.96		$ 1.69
Net Income (Loss) Attributable to Non-Participating Non-controlling Interest		$ (11)	$ 85		$ 25		$ 103

[1] Conformed to current period presentation.

[2] For the three month periods ended June 30, 2015 and 2014, excludes net increase (decrease) in equity resulting from operations of $(11) thousand and $85 thousand, respectively attributable to joint venture partners, which have non-participating interests as described in Note 9. For the six month periods ended June 30, 2015 and 2014, excludes net increase in equity resulting from operations of $25 thousand and $103 thousand, respectively attributable to joint venture partners, which have non-participating interests as described in Note 9.

[3] The Company pays quarterly dividends in arrears, so a portion of the dividends paid in each calendar year relate to the prior year's earnings.

[4] For the six month periods ended June 30, 2015 and 2014, dividends totaling $1.30 and $1.54, respectively, per common share and convertible unit outstanding, were declared and paid.