Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Net increase (decrease) in shareholders' equity resulting from operations
Net Income (Loss) Attributable to Parent	$ 19,261		$ 22,635	[1]
Net Income (Loss) Attributable to Participating Non-controlling Interest	120	[2]	185	[2]
Net income (loss) attributable to parent and participating non-controlling interest	19,381		22,820
Net increase in shareholders' equity resulting from operations– common shares	19,017		22,275
Net increase in shareholders' equity resulting from operations– LTIP units	244		360
Dividends Paid(2):
Common shareholders	(21,743)	[3]	(19,590)	[3]
LTIP unit holders	(279)	[3]	(317)	[3]
Non-controlling Interest	(137)	[3]	(163)	[3]
Total dividends paid to common shareholders, LTIP unit holders, and non-controlling interest	(22,159)	[3],[4]	(20,070)	[3],[4]
Undistributed (Distributed in excess of) earnings:
Common shareholders	(2,726)		2,685
LTIP Unit holders	(35)		43
Non-controlling interest	(17)		22
Total undistributed (distributed in excess of) earnings attributable to common shareholders, LTIP unit holders, and non-controlling interest	(2,778)		2,750
Weighted average shares outstanding (basic and diluted):
Weighted average common shares outstanding	33,449,678		23,435,571
Weighted average participating LTIP units	429,314		411,052
Weighted average non-controlling interest units	212,000		212,000
Basic earnings per common share:
Distributed (in usd per share)	$ 0.65		$ 0.77
Undistributed (Distributed in excess of) (in usd per share)	$ (0.08)		$ 0.11
Basic earnings per common share (in usd per share)	$ 0.57		$ 0.88
Diluted earnings per common share:
Distributed (in usd per share)	$ 0.65		$ 0.77
Undistributed (Distributed in excess of) (in usd per share)	$ (0.08)		$ 0.11
Diluted earnings per common share (in usd per share)	$ 0.57		$ 0.88
Net Income (Loss) Attributable to Non-Participating Non-controlling Interest	$ 36		$ 18

[1] Conformed to current period presentation.

[2] For the three month periods ended March 31, 2015 and 2014, excludes net increase in equity resulting from operations of $36.0 thousand and $18.0 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 three month periods ended March 31, 2015 and 2014, dividends totaling $0.65 and $0.77, respectively, per common share and convertible unit outstanding, were declared and paid.