Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 238,604	$ 183,808	$ 44,565
Adjustments to reconcile net income to net cash provided by operating activities (including discontinued operations):
Depreciation and amortization of buildings and improvements and leasing costs	201,482	202,108	199,558
Increase (decrease) in provision for bad debts	545	58	396
Depreciation of furniture, fixtures and equipment	2,812	2,370	1,929
Noncash amortization of share-based compensation awards (Note 13)	15,537	12,095	8,616
Noncash amortization of deferred financing costs and debt discounts and premiums	1,853	4,315	5,315
Noncash amortization of net below market rents (Note 5)	(8,449)	(8,328)	(7,777)
Disposal Group Depreciable Operating Properties, Not Discontinued Operations, Gain (Loss) on Disposal (Note 4)	(109,950)	0	0
Net gain on dispositions of discontinued operations (Note 19)	0	(121,922)	(12,252)
Gain on sale of land (Note 4)	17,116	3,490	0
Noncash amortization of deferred revenue related to tenant-funded tenant improvements (Note 9)	(13,338)	(10,979)	(10,713)
Straight-line rents	(44,383)	(31,782)	(24,135)
Net change in other operating assets	(8,085)	367	(4,615)
Net change in other operating liabilities	12,496	16,633	40,137
Insurance proceeds received for property damage and other, net	0	0	(448)
Net cash provided by operating activities	272,008	245,253	240,576
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for acquisitions of operating properties, net of cash acquired (Note 3)	0	204,546	202,682
Expenditures for acquisitions of development and redevelopment properties (Note 3)	(139,073)	(147,182)	(102,769)
Payments for Capital Improvements	99,557	132,080	129,873
Payments to Develop Real Estate Assets	407,969	417,784	320,141
Net proceeds received from dispositions of operating properties and land (Notes 4 and 19)	319,639	427,544	21,178
Issuance of Note Receivable	(3,000)	0	0
Insurance proceeds received for property damage	0	0	448
(Increase) decrease in acquisition-related deposits	1,998	(1,983)	(2,596)
(Increase) decrease in restricted cash (Note 4)	65,210	(25,405)	229,915
Net cash used in investing activities	(262,752)	(501,436)	(506,520)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from issuance of common stock (Note 11)	387,398	102,229	349,951
Borrowings on unsecured line of credit	250,000	505,000	55,000
Repayments on unsecured line of credit	(390,000)	(410,000)	(195,000)
Proceeds from the issuance of unsecured debt (Note 8)	397,776	395,528	299,901
Repayments of exchangeable senior notes (Note 8)	0	(172,500)	0
Principal payments on secured debt (Note 8)	(159,766)	(9,845)	(93,688)
Borrowings on unsecured debt (Note 8)	0	39,000
Repayments of unsecured debt (Note 8)	325,000	83,000
Financing costs	(4,814)	(8,648)	(4,384)
Repurchase of common stock and restricted stock units	(7,081)	(3,533)	(2,520)
Proceeds from exercise of stock options	14,573	21,092	128
Contributions from noncontrolling interests in consolidated subsidiary (Note 2)	474	977
Dividends and distributions paid to common stockholders and common unitholders	(126,839)	(118,463)	(111,517)
Dividends and distributions paid to preferred stockholders and preferred unitholders	(13,250)	(13,250)	(13,250)
Net cash provided by financing activities	23,471	244,587	284,621
Net increase (decrease) in cash and cash equivalents	32,727	(11,596)	18,677
Cash and cash equivalents, beginning of period	23,781	35,377	16,700
Cash and cash equivalents, end of period	56,508	23,781	35,377
SUPPLEMENTAL CASH FLOWS INFORMATION:
Cash paid for interest, net of capitalized interest of $50,923, $44,385, and $32,742 as of December 31, 2015, 2014 and 2013, respectively	54,747	58,944	65,157
NONCASH INVESTING TRANSACTIONS:
Accrual for expenditures for operating properties and development and redevelopment properties	109,715	77,091	73,482
Tenant improvements funded directly by tenants to third parties	13,837	42,906	7,633
Assumption of secured debt with property acquisition (Note 8)	0	0	95,496
Assumption of other assets and liabilities in connection with operating and development property acquisitions, net (Note 3)	6,254	14,917	1,811
Release of Holdback Funds to Third Party	9,279	0	0
Contribution of land, net of related liabilities, by noncontrolling interest to consolidated subsidiary	0	0	4,885
NONCASH FINANCING TRANSACTIONS:
Accrual of dividends and distributions payable to common stockholders and common unitholders (Note 11)	33,336	31,243	29,378
Accrual of dividends and distributions payable to preferred stockholders and preferred unitholders (Note 11)	1,656	1,656	1,694
Exchange of common units of the Operating Partnership into shares of the Company’s common stock (Note 11)	1,223	28	450
Subsidiaries [Member]
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	238,604	183,808	44,565
Adjustments to reconcile net income to net cash provided by operating activities (including discontinued operations):
Depreciation and amortization of buildings and improvements and leasing costs	201,482	202,108	199,558
Increase (decrease) in provision for bad debts	545	58	396
Depreciation of furniture, fixtures and equipment	2,812	2,370	1,929
Noncash amortization of share-based compensation awards (Note 13)	15,537	12,095	8,616
Noncash amortization of deferred financing costs and debt discounts and premiums	1,853	4,315	5,315
Noncash amortization of net below market rents (Note 5)	(8,449)	(8,328)	(7,777)
Disposal Group Depreciable Operating Properties, Not Discontinued Operations, Gain (Loss) on Disposal (Note 4)	(109,950)	0	0
Net gain on dispositions of discontinued operations (Note 19)	0	(121,922)	(12,252)
Gain on sale of land (Note 4)	17,116	3,490	0
Noncash amortization of deferred revenue related to tenant-funded tenant improvements (Note 9)	(13,338)	(10,979)	(10,713)
Straight-line rents	(44,383)	(31,782)	(24,135)
Net change in other operating assets	(8,085)	367	(4,615)
Net change in other operating liabilities	12,496	16,633	40,137
Insurance proceeds received for property damage and other, net	0	0	(448)
Net cash provided by operating activities	272,008	245,253	240,576
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for acquisitions of operating properties, net of cash acquired (Note 3)	0	204,546	202,682
Expenditures for acquisitions of development and redevelopment properties (Note 3)	(139,073)	(147,182)	(102,769)
Payments for Capital Improvements	99,557	132,080	129,873
Payments to Develop Real Estate Assets	407,969	417,784	320,141
Net proceeds received from dispositions of operating properties and land (Notes 4 and 19)	319,639	427,544	21,178
Issuance of Note Receivable	(3,000)	0	0
Insurance proceeds received for property damage	0	0	448
(Increase) decrease in acquisition-related deposits	1,998	(1,983)	(2,596)
(Increase) decrease in restricted cash (Note 4)	65,210	(25,405)	229,915
Net cash used in investing activities	(262,752)	(501,436)	(506,520)
CASH FLOWS FROM FINANCING ACTIVITIES:
Borrowings on unsecured line of credit	250,000	505,000	55,000
Repayments on unsecured line of credit	(390,000)	(410,000)	(195,000)
Proceeds from the issuance of unsecured debt (Note 8)	397,776	395,528	299,901
Repayments of exchangeable senior notes (Note 8)	0	(172,500)	0
Principal payments on secured debt (Note 8)	(159,766)	(9,845)	(93,688)
Borrowings on unsecured debt (Note 8)	0	39,000	0
Repayments of unsecured debt (Note 8)	325,000	83,000	0
Financing costs	(4,814)	(8,648)	(4,384)
Repurchase of common stock and restricted stock units	(7,081)	(3,533)	(2,520)
Proceeds from exercise of stock options	14,573	21,092	128
Contributions from noncontrolling interests in consolidated subsidiary (Note 2)	474	977	0
Dividends and distributions paid to common stockholders and common unitholders	(126,839)	(118,463)	(111,517)
Dividends and distributions paid to preferred stockholders and preferred unitholders	(13,250)	(13,250)	(13,250)
Net cash provided by financing activities	23,471	244,587	284,621
Net increase (decrease) in cash and cash equivalents	32,727	(11,596)	18,677
Cash and cash equivalents, beginning of period	23,781	35,377	16,700
Cash and cash equivalents, end of period	56,508	23,781	35,377
SUPPLEMENTAL CASH FLOWS INFORMATION:
Cash paid for interest, net of capitalized interest of $50,923, $44,385, and $32,742 as of December 31, 2015, 2014 and 2013, respectively	54,747	58,944	65,157
NONCASH INVESTING TRANSACTIONS:
Accrual for expenditures for operating properties and development and redevelopment properties	109,715	77,091	73,482
Tenant improvements funded directly by tenants to third parties	13,837	42,906	7,633
Assumption of secured debt with property acquisition (Note 8)	0	0	95,496
Assumption of other assets and liabilities in connection with operating and development property acquisitions, net (Note 3)	6,254	14,917	1,811
Release of Holdback Funds to Third Party	9,279	0	0
Contribution of land, net of related liabilities, by noncontrolling interest to consolidated subsidiary	0	0	4,885
NONCASH FINANCING TRANSACTIONS:
Accrual of dividends and distributions payable to common stockholders and common unitholders (Note 11)	33,353	31,243	29,378
Accrual of dividends and distributions payable to preferred stockholders and preferred unitholders (Note 11)	$ 1,656	$ 1,656	$ 1,694