Earnings Per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Net increase (decrease) in shareholders' equity resulting from operations
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ 11,823		$ 29,537		$ 64,274		$ 72,360
Net Income (Loss) Attributable to Noncontrolling Interest	96		0		612		0
Net Income (Loss) Attributable to Parent	11,727		29,537		63,662		72,360
Net increase in shareholders' equity resulting from operations - common shares	11,546		28,914		62,579		70,736
Net increase in shareholders' equity resulting from operations - LTIP units	181		623		1,083		1,624
Dividends Paid(1):
Common shareholders	(19,571)	[1]	(13,971)	[1]	(70,152)	[1]	(32,063)	[1]
LTIP unit holders	(306)	[1]	(273)	[1]	(1,216)	[1]	(703)	[1]
Non-controlling Interest	(163)	[1]	0	[1]	(648)	[1]	0	[1]
Total dividends paid to common shareholders, LTIP unit holders, and non-controlling interest	(20,040)	[1]	(14,244)	[1]	(72,016)	[1],[2]	(32,766)	[1],[2]
Undistributed earnings:
Common shareholders	(8,025)		14,943		(7,573)		38,673
LTIP Unit holders	(125)		350		(133)		921
Non-controlling interest	(67)		0		(36)		0
Total undistributed earnings attributable to common shareholders, LTIP unit holders, and non-controlling interest	$ (8,217)		$ 15,293		$ (7,742)		$ 39,594
Weighted average shares outstanding (basic and diluted):
Weighted average common shares outstanding	25,415,809		18,161,224		22,968,604		17,023,011
Weighted average participating LTIP units	397,897		391,604		397,366		390,871
Weighted average non-controlling interest units	212,000		0		212,000		0
Basic earnings per common share:
Distributed (in usd per share)	$ 0.77		$ 0.70		$ 3.06		$ 1.80
Undistributed (in usd per share)	$ (0.32)		$ 0.89		$ (0.33)		$ 2.35
Basic earnings per common share (in usd per share)	$ 0.45		$ 1.59		$ 2.73		$ 4.15
Diluted earnings per common share:
Distributed (in usd per share)	$ 0.77		$ 0.70		$ 3.06		$ 1.80
Undistributed (in usd per share)	$ (0.32)		$ 0.89		$ (0.33)		$ 2.35
Diluted earnings per common share (in usd per share)	$ 0.45		$ 1.59		$ 2.73		$ 4.15

[1] 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.

[2] For the nine month periods ended September 30, 2013 and 2012, dividends totaling $3.06 and $1.80, respectively, per common share and convertible unit outstanding were declared and paid.