CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Real estate properties:
Land	$ 146,700	$ 191,775
Buildings and improvements	1,100,524	1,555,836
Total real estate properties, at cost, gross	1,247,224	1,747,611
Accumulated depreciation	(379,862)	(450,718)
Total real estate properties, at cost, net	867,362	1,296,893
Assets held for sale	38,882	97,688
Acquired real estate leases, net	3,621	23,847
Cash and cash equivalents	2,837,671	2,351,693
Marketable securities	247,879	276,928
Restricted cash	6,995	8,897
Rents receivable, net of allowance for doubtful accounts of $5,137 and $4,771, respectively	55,910	93,436
Other assets, net	78,986	87,563
Total assets	4,137,306	4,236,945
LIABILITIES AND EQUITY
Senior unsecured debt, net	646,246	815,984
Mortgage notes payable, net	32,281	32,594
Liabilities related to properties held for sale	1,153	1,840
Accounts payable and accrued expenses	42,007	69,220
Assumed real estate lease obligations, net	503	1,001
Rent collected in advance	9,225	11,076
Security deposits	4,412	4,735
Total liabilities	735,827	936,450
Shareholders' equity:
Common shares of beneficial interest, $0.01 par value: 350,000,000 shares authorized; 121,457,073 and 124,217,616 shares issued and outstanding, respectively	1,214	1,242
Additional paid in capital	4,295,772	4,380,313
Cumulative net income	2,785,760	2,596,259
Cumulative other comprehensive loss	(2,106)	(95)
Cumulative common distributions	(3,111,868)	(3,111,868)
Cumulative preferred distributions	(687,745)	(685,748)
Total shareholders’ equity	3,400,290	3,299,366
Noncontrolling interest	1,189	1,129
Total equity	3,401,479	3,300,495
Total liabilities and equity	4,137,306	4,236,945
Series D
Shareholders' equity:
Series D preferred shares; 6 1/2% cumulative convertible; 4,915,196 shares issued and outstanding, aggregate liquidation preference of $122,880	119,263	119,263
Total equity	$ 119,263	$ 119,263