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	$ 447,080	$ 514,222	$ 397,089
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	209,050	193,296	182,560
Amortization of deferred financing costs	14,286	12,289	12,922
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	4,687	5,103	4,980
Non-cash interest expense related to amortization of premium on notes payable	0	0	(872)
Compensation expense related to stock-based awards	11,176	9,561	8,045
Gain on sale of real estate assets and purchase of joint venture partners' interests	0	0	(69,199)
Gain on real estate transactions, earnout on prior acquisitions and impairment of real estate	(30,807)	(112,789)	(8,465)
Distributions from unconsolidated real estate ventures in excess of earnings	6,867	4,567	3,534
Changes in operating assets and liabilities:
Other assets	(1,664)	(12,728)	(1,614)
Accounts payable and accrued expenses	2,736	(10,515)	10,075
Other liabilities	14,384	(5,631)	208
Net cash provided by operating activities	677,795	597,375	539,263
Cash flows from investing activities:
Acquisition of real estate assets	(426,388)	(653,185)	(1,086,523)
Development and redevelopment of real estate assets	(60,677)	(31,746)	(23,279)
Proceeds from sale of real estate assets, investments in real estate ventures and other assets	52,458	312,165	60,813
Investment in unconsolidated real estate ventures	(65,500)	(17,944)	(28,241)
Return of investment in unconsolidated real estate ventures	49,130	581	16,953
Issuance of notes receivable	(13,850)	0	(26,429)
Principal payments received from notes receivable	25,226	44,869	42,785
Purchase of equipment and fixtures	(4,297)	(7,819)	(4,968)
Net cash used in investing activities	(443,898)	(353,079)	(1,048,889)
Cash flows from financing activities:
Proceeds from the sale of common stock, net of offering costs	90,231	0	123,424
Proceeds from notes payable and revolving lines of credit	1,413,030	1,325,623	1,900,357
Principal payments on notes payable and revolving lines of credit	(1,109,854)	(1,088,679)	(1,122,442)
Principal payments on notes payable to trusts	(88,662)	0	0
Deferred financing costs	(12,302)	(6,967)	(17,486)
Repurchase of exchangeable senior notes	(80,270)	(19,916)	(22,195)
Net proceeds from exercise of stock options	1,169	1,266	1,444
Proceeds from termination of interest rate cap	0	0	1,650
Payment of earnout from prior acquisition	0	0	(4,600)
Redemption of Operating Partnership units held by noncontrolling interests	(2,558)	(2,510)	(506)
Contributions from noncontrolling interests	122	201	0
Dividends paid on common stock	(424,907)	(393,040)	(367,818)
Distributions to noncontrolling interests	(33,250)	(31,972)	(30,997)
Net cash (used in) provided by financing activities	(247,251)	(215,994)	460,831
Net increase (decrease) in cash, cash equivalents, and restricted cash	(13,354)	28,302	(48,795)
Cash, cash equivalents, and restricted cash, beginning of the period	86,044	57,742	106,537
Cash, cash equivalents, and restricted cash end of the period	72,690	86,044	57,742
Supplemental schedule of cash flow information
Interest paid	159,474	136,202	122,265
Income taxes paid	730	5,648	14,864
Redemption of Operating Partnership units held by noncontrolling interests for common stock
Common stock and paid-in capital	1,337	0	577
Tax effect from vesting of restricted stock grants and option exercises
Other assets	0	0	2,404
Additional paid-in capital	0	0	(2,404)
Acquisitions of real estate assets
Real estate assets	457,617	627,462
Notes payable assumed	(87,500)	(24,055)
Investment in unconsolidated real estate ventures			0
Accrued construction costs and capital expenditures
Acquisition of real estate assets	778	3,509	8,497
Development and redevelopment of real estate assets	554	1,703	125
Accounts payable and accrued expenses	(1,332)	(5,212)	(8,622)
Distribution of real estate from investments in unconsolidated real estate ventures
Real estate assets, net	0	0	25,055
Investments in unconsolidated real estate ventures	0	0	(25,055)
Disposition of real estate assets
Real estate assets, net	0	0	(7,869)
Issuance of Preferred OP Units for additional investment in unconsolidated real estate venture
Preferred OP Units issued	0	(4,351)	0
Investment in unconsolidated real estate ventures	0	4,351	0
Acquisitions of real estate assets
Acquisitions of real estate assets
Real estate assets	88,842	51,455	84,163
Value of Operating Partnership units issued	(1,877)	(14,428)	(74,440)
Notes payable assumed	(87,500)	(24,055)	(9,723)
Investment in unconsolidated real estate ventures	535	(12,957)
Other noncontrolling interests	0	(15)	0
Operating Partnership units redeemed
Redemption of Operating Partnership units held by noncontrolling interests for common stock
Noncontrolling interests in Operating Partnership	(1,337)	0	(577)
Disposition of real estate assets
Operating Partnership units redeemed	0	0	7,869
Acquisition of noncontrolling interests
Acquisition of noncontrolling interests
Operating Partnership units issued	0	0	(800)
Other noncontrolling interests	0	0	162
Additional paid-in capital	$ 0	$ 0	$ 638