Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Cash flows from operating activities:
Net income	$ 211,558	$ 167,505
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	372,210	369,223
(Gain) loss on sale of depreciable real estate assets	(987)	21
Gain on sale of non-depreciable real estate assets	(9,260)	(3,870)
Stock compensation expense	11,550	9,877
Amortization of debt discounts, premiums and issuance costs	4,706	(4,318)
Net change in operating accounts and other	31,761	62,618
(Gain) loss on sale of depreciable real estate assets	987	(21)
Stock compensation expense	(11,550)	(9,877)
Net cash provided by operating activities	621,538	601,056
Cash flows from investing activities:
Purchases of real estate and other assets	(22,860)	(112,656)
Capital improvements, development and other	(219,670)	(192,520)
Distributions from real estate joint ventures	365
Contributions to affiliates	(4,500)	(1,500)
Proceeds from disposition of real estate assets	15,984	18,918
Net cash used in investing activities	(230,681)	(287,758)
Cash flows from financing activities:
Proceeds from lines of credit	565,000	780,000
Repayments of lines of credit	(1,105,000)	(820,000)
Net proceeds from commercial paper	200,000
Proceeds from notes payable	760,003	397,612
Principal payments on notes payable	(468,635)	(346,239)
Payment of deferred financing costs	(11,530)	(3,741)
Distributions to noncontrolling interests	(11,813)	(11,286)
Distributions paid on common shares/units	(328,239)	(314,834)
Distributions paid on preferred shares/units	(2,766)	(2,766)
Net change in other financing activities	3,132	(1,511)
Net cash used in financing activities	(399,848)	(322,765)
Net decrease in cash, cash equivalents and restricted cash	(8,991)	(9,467)
Cash, cash equivalents and restricted cash, beginning of period	51,673	88,867
Cash, cash equivalents and restricted cash, end of period	42,682	79,400
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	25,826	46,139
Restricted cash	16,856	33,261
Cash, cash equivalents and restricted cash, end of period	42,682	79,400
Supplemental disclosure of cash flow information:
Interest paid	108,249	111,439
Income taxes paid	2,509	2,746
Supplemental disclosure of noncash investing and financing activities:
Conversion of OP Units to shares of common stock	1,993	4,282
Accrued construction in progress	14,652	19,476
Interest capitalized	1,847	1,640
Fair value adjustment on derivative instruments	11,248	7,956
Limited Partner [Member]
Cash flows from operating activities:
Net income	211,558	167,505
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	372,210	369,223
(Gain) loss on sale of depreciable real estate assets	987	(21)
Gain on sale of non-depreciable real estate assets	(9,260)	(3,870)
Stock compensation expense	(11,550)	(9,877)
Amortization of debt discounts, premiums and issuance costs	4,706	(4,318)
Net change in operating accounts and other	31,761	62,618
(Gain) loss on sale of depreciable real estate assets	(987)	21
Stock compensation expense	11,550	9,877
Net cash provided by operating activities	621,538	601,056
Cash flows from investing activities:
Purchases of real estate and other assets	(22,860)	(112,656)
Capital improvements, development and other	(219,670)	(192,520)
Distributions from real estate joint ventures	365
Contributions to affiliates	(4,500)	(1,500)
Proceeds from disposition of real estate assets	15,984	18,918
Net cash used in investing activities	(230,681)	(287,758)
Cash flows from financing activities:
Proceeds from lines of credit	565,000	780,000
Repayments of lines of credit	(1,105,000)	(820,000)
Net proceeds from commercial paper	200,000
Proceeds from notes payable	760,003	397,612
Principal payments on notes payable	(468,635)	(346,239)
Payment of deferred financing costs	(11,530)	(3,741)
Distributions paid on common shares/units	(340,052)	(326,120)
Distributions paid on preferred shares/units	(2,766)	(2,766)
Net change in other financing activities	3,132	(1,511)
Net cash used in financing activities	(399,848)	(322,765)
Net decrease in cash, cash equivalents and restricted cash	(8,991)	(9,467)
Cash, cash equivalents and restricted cash, beginning of period	51,673	88,867
Cash, cash equivalents and restricted cash, end of period	42,682	79,400
Reconciliation of cash, cash equivalents and restricted cash:
Cash and cash equivalents	25,826	46,139
Restricted cash	16,856	33,261
Cash, cash equivalents and restricted cash, end of period	42,682	79,400
Supplemental disclosure of cash flow information:
Interest paid	108,249	111,439
Income taxes paid	2,509	2,746
Supplemental disclosure of noncash investing and financing activities:
Accrued construction in progress	14,652	19,476
Interest capitalized	1,847	1,640
Fair value adjustment on derivative instruments	$ 11,248	$ 7,956