CONSOLIDATED STATEMENTS OF EQUITY AND COMPREHENSIVE INCOME (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income	Cumulative Earnings	Cumulative Distributions to Stockholders	Noncontrolling Interest
Beginning balance at Dec. 31, 2009	$ 989,091	$ 777	$ 1,674,367	$ 64,860	$ 364,888	$ (1,133,171)	$ 17,370
Beginning balance (in shares) at Dec. 31, 2009		77,737,130
Net income (loss)	75,615				75,444		171
Net unrealized (loss) gain on available-for-sale securities	(10,897)			(12,987)			2,090
Reclassification of other-than-temporary impairments to net income	5,411			5,411
Net unrealized loss on interest rate agreements	(20,631)			(20,631)
Reclassification of unrealized loss on interest rate agreements to net income	1,546			1,546
Total other comprehensive loss				(26,661)
Total comprehensive loss / gain	51,044
Issuance of common stock:
Dividend reinvestment & stock purchase plans (in shares)		122,483
Dividend reinvestment & stock purchase plans	1,976	2	1,974
Employee stock purchase and incentive plans (in shares)		48,826
Employee stock purchase and incentive plans	(245)		(245)
Non-cash equity award compensation	8,208		8,208
Distributions to noncontrolling interest, net	(7,638)						(7,638)
Common dividends declared	(39,908)					(39,908)
Ending balance at Jun. 30, 2010	1,002,528	779	1,684,304	38,199	440,332	(1,173,079)	11,993
Ending balance (in shares) at Jun. 30, 2010		77,908,439
Beginning balance at Dec. 31, 2010	1,075,592	781	1,689,851	112,339	474,940	(1,213,158)	10,839
Beginning balance (in shares) at Dec. 31, 2010		78,124,668
Net income (loss)	26,477				27,604		(1,127)
Net unrealized (loss) gain on available-for-sale securities	(30,519)			(34,683)			4,164
Reclassification of other-than-temporary impairments to net income	2,349			2,349
Net unrealized loss on interest rate agreements	(1,528)			(1,528)
Reclassification of unrealized loss on interest rate agreements to net income	2,144			2,144
Total other comprehensive loss				(31,718)
Total comprehensive loss / gain	(1,077)
Issuance of common stock:
Dividend reinvestment & stock purchase plans (in shares)		158,028
Dividend reinvestment & stock purchase plans	2,351	2	2,349
Employee stock purchase and incentive plans (in shares)		272,269
Employee stock purchase and incentive plans	(2,926)	3	(2,929)
Non-cash equity award compensation	4,806		4,806
Distributions to noncontrolling interest, net	(11,770)						(11,770)
Common dividends declared	(40,360)					(40,360)
Ending balance at Jun. 30, 2011	$ 1,026,616	$ 786	$ 1,694,077	$ 80,621	$ 502,544	$ (1,253,518)	$ 2,106
Ending balance (in shares) at Jun. 30, 2011		78,554,965