Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Parent Company [Member]
Cash flows from operating activities:
Consolidated net income	$ 112,801	$ 93,571
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	(244,521)	(256,872)
(Gain) Loss on sale of depreciable real estate assets excluded from discontinued operations	(2)	(201)
Gain on sale of non-depreciable real estate assets	(2,911)	(48)
Stock compensation expense	6,987	5,618
Amortization of debt premium	(2,969)	(6,023)
Proceeds from Other Operating Activities	5,578	(28,566)
Net cash provided by operating activities	364,005	321,223
Cash flows from investing activities:
Purchases of real estate and other assets	(110,430)	(62,817)
Normal capital improvements	(126,333)	(186,372)
Contributions to Real Estate Joint Ventures	(750)	0
Proceeds from disposition of real estate assets	16,151	1,551
Net cash (used in) provided by investing activities	(221,362)	(247,638)
Cash flows from financing activities:
Proceeds from Lines of Credit	355,000	375,000
Repayments of Lines of Credit	655,000	705,000
Proceeds from notes payable	397,612	597,480
Principal payments on notes payable	(43,622)	(178,164)
Payment of deferred financing costs	3,471	5,257
Repurchase of common stock	(2,912)	(4,782)
Payment for Debt Extinguishment or Debt Prepayment Cost	(3)	(1,581)
Proceeds from issuances of common shares	436	783
Proceeds from Stock Options Exercised	625	432
Distributions to noncontrolling interests	(7,685)	(7,332)
Dividends paid on common shares	(209,843)	(197,602)
Dividends, Preferred Stock, Cash	(1,844)	(1,844)
Net cash used in financing activities	(170,707)	(127,867)
Net (decrease) increase in cash and cash equivalents	(28,064)	(54,282)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning	88,867	121,800
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	60,803	67,518
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	32,610	39,659
Restricted Cash	28,193	27,859
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	60,803	67,518
Supplemental disclosure of cash flow information:
Interest paid	87,872	79,981
Income Taxes Paid	2,670	2,226
Supplemental disclosure of noncash investing and financing activities:
Conversion of units to shares of common stock	3,118	265
Accrued construction in progress	22,109	19,360
Interest capitalized	1,283	4,227
Marked To Market Adjustment On Derivative Instruments	4,597	6,757
Limited Partner [Member]
Cash flows from operating activities:
Consolidated net income	112,801	93,571
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	(244,521)	(256,872)
(Gain) Loss on sale of depreciable real estate assets excluded from discontinued operations	(2)	(201)
Gain on sale of non-depreciable real estate assets	(2,911)	(48)
Stock compensation expense	6,987	5,618
Amortization of debt premium	(2,969)	(6,023)
Proceeds from Other Operating Activities	5,578	(28,566)
Net cash provided by operating activities	364,005	321,223
Cash flows from investing activities:
Purchases of real estate and other assets	(110,430)	(62,817)
Normal capital improvements	(126,333)	(186,372)
Contributions to Real Estate Joint Ventures	(750)	0
Proceeds from disposition of real estate assets	16,151	1,551
Net cash (used in) provided by investing activities	(221,362)	(247,638)
Cash flows from financing activities:
Proceeds from Lines of Credit	355,000	375,000
Repayments of Lines of Credit	655,000	705,000
Proceeds from notes payable	397,612	597,480
Principal payments on notes payable	(43,622)	(178,164)
Payment of deferred financing costs	3,471	5,257
Repurchase of common units	(2,912)	(4,782)
Payment for Debt Extinguishment or Debt Prepayment Cost	(3)	(1,581)
Proceeds from issuances of common units	436	783
Proceeds from Stock Options Exercised	625	432
Distributions paid on common units	(217,528)	(204,934)
Dividends, Preferred Stock, Cash	(1,844)	(1,844)
Net cash used in financing activities	(170,707)	(127,867)
Net (decrease) increase in cash and cash equivalents	(28,064)	(54,282)
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Beginning	88,867	121,800
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	60,803	67,518
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents [Abstract]
Cash and cash equivalents	32,610	39,659
Restricted Cash	28,193	27,859
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending	60,803	67,518
Supplemental disclosure of cash flow information:
Interest paid	87,872	79,981
Income Taxes Paid	2,670	2,226
Supplemental disclosure of noncash investing and financing activities:
Accrued construction in progress	22,109	19,360
Interest capitalized	1,283	4,227
Marked To Market Adjustment On Derivative Instruments	$ 4,597	$ 6,757