Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 303,798	$ 238,604	$ 183,808
Adjustments to reconcile net income to net cash provided by operating activities (including discontinued operations):
Depreciation and amortization of real estate assets and leasing costs	213,156	201,482	202,108
Depreciation of non-real estate furniture, fixtures and equipment	4,078	2,812	2,370
Increase in provision for bad debts	0	545	58
Non-cash amortization of share-based compensation awards	21,064	15,537	12,095
Non-cash amortization of deferred financing costs and debt discounts and premiums	2,720	1,853	4,315
Non-cash amortization of net below market rents	(7,166)	(8,449)	(8,328)
Gains on sales of depreciable operating properties	(164,302)	(109,950)	0
Gains on sales of discontinued operations	0	0	(121,922)
Loss (gain) on sales of land	(295)	17,116	3,490
Non-cash amortization of deferred revenue related to tenant-funded tenant improvements	(13,244)	(13,338)	(10,979)
Straight-line rents	(29,629)	(44,383)	(31,782)
Net change in other operating assets	(5,214)	(8,085)	367
Net change in other operating liabilities	19,498	12,496	16,633
Net cash provided by operating activities	345,054	272,008	245,253
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for development properties and undeveloped land	351,012	407,969	417,784
Expenditures for acquisitions of development properties and undeveloped land	(33,513)	(139,073)	(147,182)
Expenditures for acquisitions of operating properties	393,767	0	204,546
Expenditures for operating properties and other capital assets	111,961	99,557	132,080
Net proceeds received from dispositions	325,031	319,639	427,544
Net decrease (increase) in restricted cash	(56,015)	65,210	(25,405)
Issuance of notes receivable	(16,100)	(3,000)	0
Decrease (increase) in acquisition-related deposits	1,902	1,998	(1,983)
Net cash used in investing activities	(635,435)	(262,752)	(501,436)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings on unsecured revolving credit facility	305,000	250,000	505,000
Repayments on unsecured revolving credit facility	(305,000)	(390,000)	(410,000)
Proceeds from the issuance of secured debt	170,000	0	0
Principal payments and repayments of secured debt	(74,140)	(159,766)	(9,845)
Net proceeds from the issuance of unsecured debt	0	397,776	395,528
Repayments of unsecured debt	0	325,000	83,000
Repayments of exchangeable senior notes	0	0	(172,500)
Borrowings on unsecured debt	0	0	39,000
Financing costs	(2,159)	(4,814)	(8,648)
Net proceeds from issuance of common stock	31,117	387,398	102,229
Proceeds from exercise of stock options	12,208	14,573	21,092
Repurchase of common stock and restricted stock units	(8,875)	(7,081)	(3,533)
Contributions from noncontrolling interests in consolidated property partnerships	453,449	474	977
Distributions to noncontrolling interests in consolidated property partnerships	(3,615)	0	0
Dividends and distributions paid to common stockholders and common unitholders	(137,444)	(126,839)	(118,463)
Dividends and distributions paid to preferred stockholders and preferred unitholders	(13,250)	(13,250)	(13,250)
Net cash provided by financing activities	427,291	23,471	244,587
Net increase (decrease) in cash and cash equivalents	136,910	32,727	(11,596)
Cash and cash equivalents, beginning of year	56,508	23,781	35,377
Cash and cash equivalents, end of year	$ 193,418	$ 56,508	$ 23,781