Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Sep. 30, 2016
PROPERTIES:
Accumulated depreciation on operating properties	$ 352,350	$ 328,790
Real Estate Held for Sale, Accumulated Depreciation	7,200	119,670
Allowance for doubtful accounts for notes and other receivables	1,353	1,128
Intangible Liabilities, Accumulated Amortization	26,890	32,922
Disposal Group, Including Discontinued Operation, Liabilities, Current	1,347	106,135
Finite-Lived Intangible Assets, Accumulated Amortization	$ 103,458	$ 110,679
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	350,000,000	350,000,000
Common stock, shares issued	220,255,676	220,498,850
Treasury stock, shares	8,742,181	10,329,082
Preferred stock, dividend rate
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Preferred stock, liquidation preference	$ 0