CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Real estate:
Buildings and improvements	$ 11,239,732	$ 11,692,654
Development costs and construction in progress	447,976	400,619
Land	1,785,865	1,881,487
Accumulated depreciation and amortization	(2,741,695)	(2,648,930)
Net real estate	10,731,878	11,325,830
Net investment in direct financing leases	714,352	752,589
Loans receivable, net	313,326	807,954
Investments in and advances to unconsolidated joint ventures	800,840	571,491
Accounts receivable, net of allowance of $4,425 and $4,459, respectively	40,733	45,116
Cash and cash equivalents	55,306	94,730
Restricted cash	26,897	42,260
Intangible assets, net	410,082	479,805
Assets held for sale, net	417,014	927,866
Other assets, net	578,033	711,624
Total assets	14,088,461	15,759,265
LIABILITIES AND EQUITY
Bank line of credit	1,017,076	899,718
Term loans	228,288	440,062
Senior unsecured notes	6,396,451	7,133,538
Mortgage debt	144,486	623,792
Other debt	94,165	92,385
Intangible liabilities, net	52,579	58,145
Liabilities of assets held for sale, net	14,031	3,776
Accounts payable and accrued liabilities	401,738	417,360
Deferred revenue	144,709	149,181
Total liabilities	8,493,523	9,817,957
Commitments and contingencies
Common stock, $1.00 par value: 750,000,000 shares authorized; 469,435,678 and 468,081,489 shares issued and outstanding, respectively	469,436	468,081
Additional paid-in capital	8,226,113	8,198,890
Cumulative dividends in excess of earnings	(3,370,520)	(3,089,734)
Accumulated other comprehensive income (loss)	(24,024)	(29,642)
Total stockholders' equity	5,301,005	5,547,595
Joint venture partners	117,045	214,377
Non-managing member unitholders	176,888	179,336
Total noncontrolling interests	293,933	393,713
Total equity	5,594,938	5,941,308
Total liabilities and equity	$ 14,088,461	$ 15,759,265