Condensed Consolidated Statements of Equity (Unaudited) (USD $) In Thousands, unless otherwise specified	Series H Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Distributions in Excess of Accumulated Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]	Total
Balances at Dec. 31, 2011	$ 73,750	$ 3	$ 1,844,611	$ (408,066)	$ (72,771)	$ 116,201	$ 1,553,728
Balances (in shares) at Dec. 31, 2011	2,950	33,888
Comprehensive income (loss):
Net income	0	0	0	24,090	0	3,151	27,241
Changes in fair value of cash flow hedges and amortization of settlement swaps	0	0	0	0	1,880	124	2,004
Changes in fair value of marketable securities	0	0	0	0	326	21	347
Issuance of common stock under:
Stock option plans	0	0	1,348	0	0	0	1,348
Stock option plans (in shares)		24
Sale of common stock	0	0	31,590	0	0	0	31,590
Sale of common stock (in shares)		221
Equity based compensation costs	0	0	(176)	0	0	596	420
Dividend declared	0	0	0	(38,943)	0	0	0
Redemption of Series B Preferred	0	0	0	0	0	0	0
Redemptions of noncontrolling interest	0	0	0	0	0	(435)	(435)
Distributions to noncontrolling interest	0	0	0	0	0	(3,850)	(3,850)
Common and preferred stock dividends	0	0	0	(38,943)	0	0	0
Balances at Mar. 31, 2012	$ 73,750	$ 3	$ 1,877,373	$ (422,919)	$ (70,565)	$ 115,808	$ 1,573,450
Balances (in shares) at Mar. 31, 2012	2,950	34,133