CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 146,551	$ 133,931
Adjustments to net income:
Depreciation and amortization	218,275	199,138
Amortization of share-based compensation	6,552	5,362
Non-cash rental adjustments	(5,279)	(4,939)
Amortization of net premiums on mortgages payable	(1,855)	(3,824)
Amortization of deferred financing costs	4,384	6,509
Loss on interest rate swaps	7,886	1,958
Gain on sales of real estate	(10,948)	(10,893)
Provisions for impairment on real estate	8,192	5,317
Change in assets and liabilities
Accounts receivable and other assets	6,946	1,778
Accounts payable, accrued expenses and other liabilities	(19,277)	(12,627)
Net cash provided by operating activities	361,427	321,710
CASH FLOWS FROM INVESTING ACTIVITIES
Investment in real estate	(618,340)	(924,541)
Improvements to real estate, including leasing costs	(2,934)	(2,470)
Proceeds from sale of real estate	35,020	30,455
Collection of loans receivable	12,457
Restricted escrow deposits for Section 1031 tax-deferred exchanges and pending acquisitions	(17,291)	21,313
Net cash used in investing activities	(591,088)	(875,243)
CASH FLOWS FROM FINANCING ACTIVITIES
Cash distributions to common stockholders	(298,581)	(258,277)
Cash dividends to preferred stockholders	(13,540)	(13,540)
Borrowings on line of credit	2,244,000	957,000
Payments on line of credit	(1,970,000)	(750,000)
Principal payments on mortgages payable	(181,333)	(79,291)
Proceeds from term loans		250,000
Proceeds from common stock offerings, net	383,525	276,430
Redemption of preferred units		(6,750)
Distributions to noncontrolling interests	(747)	(848)
Debt issuance costs		(10,204)
Proceeds from dividend reinvestment and stock purchase plan	5,806	208,033
Procceds from At-the-Market (ATM) program	44,565
Other items, including shares withheld upon vesting	(3,885)	(4,131)
Net cash provided by financing activities	209,810	568,422
Net (decrease) increase in cash and cash equivalents	(19,851)	14,889
Cash and cash equivalents, beginning of period	40,294	3,852
Cash and cash equivalents, end of period	$ 20,443	$ 18,741