Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
PROPERTIES:
Accumulated depreciation on operating properties	$ 298,085	$ 274,925
Allowance for doubtful accounts for notes and other receivables	$ 5,646	$ 6,287
Preferred stock, 20,000,000 shares authorized, $1 par value:
Preferred stock, par value	$ 1	$ 1
Preferred stock, shares authorized	20,000,000	20,000,000
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	107,283,901	106,961,959
Treasury stock, shares	3,570,082	3,570,082
Series A Preferred Stock [Member]
Preferred stock, 20,000,000 shares authorized, $1 par value:
Preferred stock, dividend rate	7.75%	7.75%
Preferred stock, shares issued	2,993,090	2,993,090
Preferred stock, shares outstanding	2,993,090	2,993,090
Preferred stock, liquidation preference	$ 25	$ 25
Series B Preferred Stock [Member]
Preferred stock, 20,000,000 shares authorized, $1 par value:
Preferred stock, dividend rate	7.50%	7.50%
Preferred stock, shares issued	3,791,000	3,791,000
Preferred stock, shares outstanding	3,791,000	3,791,000
Preferred stock, liquidation preference	$ 25	$ 25