Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Cumulative Net Income	Cumulative Dividends	Total Stockholders' Equity	Non-controlling Interests
Beginning Balance at Dec. 31, 2008	$ 796,247	$ 0	$ 592	$ 1,490,535	$ (6,461)	$ 736,874	$ (1,426,720)	$ 794,820	$ 1,427
Issuance of stock, net of costs	26,669		13	26,656				26,669
Common stock redemption	(8)			(8)				(8)
Stock-based compensation	3,711		1	3,710				3,711
Net income (loss)	51,148					51,091		51,091	57
Other comprehensive income (loss)	1,868				(1,868)			(1,868)
Dividends to common stockholders $1.54, $1.20 and $1.20 per share for the year ended 2009, 2010 and 2011 respectively	(91,385)						(91,385)	(91,385)
Distributions to noncontrolling interests	(330)								(330)
Proceeds from noncontrolling interests	2,228								2,228
Ending Balance at Dec. 31, 2009	790,148	0	606	1,520,893	(4,593)	787,965	(1,518,105)	786,766	3,382
Issuance of stock, net of costs	118,130		53	118,077				118,130
Stock-based compensation	2,411		2	2,409				2,411
Net income (loss)	8,247					8,200		8,200	47
Other comprehensive income (loss)	(676)				676			676
Dividends to common stockholders $1.54, $1.20 and $1.20 per share for the year ended 2009, 2010 and 2011 respectively	(75,821)						(75,821)	(75,821)
Distributions to noncontrolling interests	(467)								(467)
Proceeds from noncontrolling interests	768								768
Ending Balance at Dec. 31, 2010	842,740	0	661	1,641,379	(5,269)	796,165	(1,593,926)	839,010	3,730
Issuance of stock, net of costs	251,976		117	251,859				251,976
Common stock redemption	(86)			(86)				(86)
Stock-based compensation	2,922		1	2,921				2,922
Net income (loss)	(184)					(214)		(214)	30
Other comprehensive income (loss)	1,937				(1,937)			(1,937)
Dividends to common stockholders $1.54, $1.20 and $1.20 per share for the year ended 2009, 2010 and 2011 respectively	(89,270)						(89,270)	(89,270)
Distributions to noncontrolling interests	(249)								(249)
Proceeds from noncontrolling interests	76								76
Purchase of noncontrolling interest in consolidated joint ventures	(5,056)			(1,469)				(1,469)	(3,587)
Ending Balance at Dec. 31, 2011	$ 1,004,806	$ 0	$ 779	$ 1,894,604	$ (3,332)	$ 795,951	$ (1,683,196)	$ 1,004,806	$ 0