Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Jun. 30, 2016
PROPERTIES:
Accumulated depreciation on operating properties	$ 352,350	$ 377,418
Real Estate Held for Sale, Accumulated Depreciation	7,200	0
Allowance for doubtful accounts for notes and other receivables	1,353	1,467
Intangible Liabilities, Accumulated Amortization	26,890	29,199
Disposal Group, Including Discontinued Operation, Liabilities, Current	1,347	0
Finite-Lived Intangible Assets, Accumulated Amortization	$ 103,458	$ 109,328
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	220,436,378
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