Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net income	$ 183,832	$ 179,447
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	96,064	86,847
Amortization of deferred financing costs	6,083	5,617
Non-cash interest expense related to amortization of discount on equity component of exchangeable senior notes	2,559	2,473
Non-cash interest expense related to amortization of premium on notes payable	0	(696)
Compensation expense related to stock-based awards	4,955	4,093
Gain on purchase of joint venture partner's interest	0	(26,923)
(Gain) loss on real estate transactions, earnout from prior acquisition and impairment of real estate	6,019	(9,814)
Distributions from unconsolidated real estate ventures in excess of earnings	2,365	1,936
Changes in operating assets and liabilities:
Receivables from related parties and affiliated real estate joint ventures	137	1,720
Other assets	15,066	(1,186)
Accounts payable and accrued expenses	(18,090)	(402)
Other liabilities	(9,941)	(3,442)
Net Cash Provided by (Used in) Operating Activities	289,049	239,670
Cash flows from investing activities:
Acquisition of real estate assets	(72,651)	(435,298)
Development and redevelopment of real estate assets	(12,274)	(14,400)
Proceeds from sale of real estate assets, investments in real estate ventures and other assets	101	17,582
Change in restricted cash	(2,880)	15,506
Investment in unconsolidated real estate ventures	(2,670)	(19,309)
Return of investment in unconsolidated real estate ventures	581	1,318
Purchase/issuance of notes receivable	0	(10,656)
Principal payments received from notes receivable	44,869	41,393
Purchase of equipment and fixtures	(4,110)	(2,128)
Net Cash Provided by (Used in) Investing Activities	(49,034)	(405,992)
Cash flows from financing activities:
Proceeds from the sale of common stock, net of offering costs	0	73,369
Repurchase of exchangeable senior notes	0	(22,192)
Proceeds from notes payable and revolving lines of credit	652,446	492,880
Principal payments on notes payable and revolving lines of credit	(686,443)	(222,923)
Deferred financing costs	(2,925)	(5,702)
Net proceeds from exercise of stock options	0	313
Proceeds from termination of interest rate cap	0	1,650
Redemption of Operating Partnership units held by noncontrolling interests	(2,510)	0
Dividends paid on common stock	(196,468)	(171,514)
Distributions to noncontrolling interests	(16,325)	(14,300)
Net cash provided by (used in) financing activities	(252,225)	131,581
Net decrease in cash and cash equivalents	(12,210)	(34,741)
Cash and cash equivalents, beginning of the period	43,858	75,799
Cash and cash equivalents, end of the period	31,648	41,058
Supplemental schedule of cash flow information
Interest paid	67,808	59,676
Income taxes paid	7,544	8,516
Redemption of Operating Partnership units held by noncontrolling interests for common stock:
Noncontrolling interests in Operating Partnership	0	(829)
Common stock and paid-in capital	0	829
Tax effect from vesting of restricted stock grants and option exercises
Other assets	0	1,267
Additional paid-in capital	0	(1,267)
Accrued construction costs and capital expenditures
Acquisition of real estate assets	6,580	7,567
Development and redevelopment of real estate assets	2,798	1,298
Other liabilities	(9,378)	(8,865)
Distribution of real estate from investments in unconsolidated real estate ventures
Real estate assets, net	0	17,261
Investments in unconsolidated real estate ventures	0	(17,261)
Disposition of real estate assets
Real estate assets, net	0	(7,689)
Acquisitions Of Real Estate [Member]
Value of OP Units Issued	(6,810)	(56,237)
Loan Assumed	(9,463)	(9,723)
Acquisitions of real estate assets
Real estate assets, net	18,100	65,960
Other noncontrolling interests	(1,827)	0
Redemption Of Operating Partnership Units [Member]
Disposition of real estate assets
Operating Partnership units redeemed	$ 0	$ 7,689