CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 364,598	$ 319,318	$ 316,477
Adjustments to net income:
Depreciation and amortization	539,780	498,788	449,943
Loss on extinguishment of debt	0	42,426	0
Amortization of share-based compensation	27,267	13,946	12,007
Non-cash revenue adjustments	(7,835)	(3,927)	(10,154)
Amortization of net premiums on mortgages payable	(1,520)	(466)	(3,414)
Amortization of net (premiums) discounts on notes payable	(1,256)	884	1,470
Amortization of deferred financing costs	9,021	8,274	7,434
Gain on interest rate swaps	(2,733)	(3,250)	(1,639)
Gain on sales of real estate	(24,643)	(40,898)	(21,979)
Provisions for impairment on real estate	26,269	14,751	20,664
Change in assets and liabilities
Accounts receivable and other assets	(6,901)	(92)	(5,414)
Accounts payable, accrued expenses and other liabilities	18,695	26,096	34,468
Net cash provided by operating activities	940,742	875,850	799,863
CASH FLOWS FROM INVESTING ACTIVITIES
Investment in real estate	(1,769,335)	(1,413,270)	(1,798,892)
Improvements to real estate, including leasing costs	(25,350)	(15,247)	(13,426)
Proceeds from sales of real estate	142,286	166,976	99,096
Insurance and other proceeds received	7,648	14,411	0
Collection of loans receivable	5,267	123	12,515
Non-refundable escrow deposits for pending acquisitions	(200)	(7,500)	0
Net cash used in investing activities	(1,639,684)	(1,254,507)	(1,700,707)
CASH FLOWS FROM FINANCING ACTIVITIES
Cash distributions to common stockholders	(761,582)	(689,294)	(610,516)
Cash dividends to preferred stockholders	0	(6,168)	(27,080)
Borrowings on line of credit	1,774,000	1,465,000	3,879,000
Payments on line of credit	(1,632,000)	(2,475,000)	(2,997,000)
Principal payment on term loan	(125,866)	0	0
Proceeds from notes and bonds payable issued	497,500	2,033,041	592,026
Principal payment on notes payable	(350,000)	(725,000)	(275,000)
Proceeds from term loan	250,000	0	0
Proceeds from mortgages payable	0	0	9,963
Payments upon extinguishment of debt	0	(41,643)	0
Principal payments on mortgages payable	(21,905)	(139,725)	(231,743)
Redemption of preferred stock	0	(408,750)	0
Proceeds from common stock offerings, net	0	704,938	383,572
Proceeds from dividend reinvestment and stock purchase plan	9,114	69,931	10,252
Proceeds from At-the-Market (ATM) program	1,125,364	621,697	166,781
Redemption of common units	(2,752)	0	(9,026)
Distributions to noncontrolling interests	(1,930)	(2,043)	(12,725)
Debt issuance costs	(18,685)	(17,510)	(5,274)
Other items, including shares withheld upon vesting	(33,387)	(14,356)	(7,038)
Net cash provided by financing activities	707,871	375,118	866,192
Net increase (decrease) in cash, cash equivalents and restricted cash	8,929	(3,539)	(34,652)
Cash, cash equivalents and restricted cash, beginning of period	12,142	15,681	50,333
Cash, cash equivalents and restricted cash, end of period	$ 21,071	$ 12,142	$ 15,681