Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2014
Real estate assets:
Accumulated depreciation on operating properties	$ 235,707	$ 297,034
Development in Process, Accumulated Depreciation	0	0
Real Estate Held for Sale, Accumulated Depreciation	21,444	14,851
Finite-Lived Intangible Assets, Accumulated Amortization	37,544	64,947
Allowance for doubtful accounts for notes and other receivables	$ 1,827	$ 1,635
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
Preferred Stock, Dividend Rate, Percentage	7.50%
Preferred stock, shares issued	3,791,000	0
Preferred Stock, Shares Outstanding	3,791,000	0
Preferred Stock, Liquidation Preference Per Share	$ 25
Common stock, par value	$ 1	$ 1
Common stock, shares authorized	250,000,000	350,000,000
Treasury stock, shares	3,570,082	3,570,082