Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Accumulated depreciation on operating properties	$ 692,126	$ 577,139
Real estate assets and other assets held for sale, accumulated depreciation and amortization		61,093
Accumulated amortization on intangible liabilities	$ 66,343	55,798
Accumulated amortization on liabilities of real estate assets held for sale		$ 7,771
Preferred stock, par value (in usd per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)		1,716,837
Preferred stock, shares outstanding (in shares)	0	1,716,837
Common stock, par value (in usd per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	151,153,042	149,347,382
Common stock, shares outstanding (in shares)	148,568,109	146,762,449
Treasury stock, shares (in shares)	2,584,933	2,584,933