Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Cash flows from operating activities:
Net income	$ 57,944	$ 70,534	$ 202,127	$ 172,588
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			282,639	266,812
Amortization of deferred loan costs and debt premiums			8,533	7,599
(Accretion) and amortization of above and below market lease intangibles, net			(30,196)	(26,031)
Stock-based compensation, net of capitalization			10,716	10,012
Equity in income of investments in real estate partnerships	283	(10,024)	(43,673)	(29,548)
Gain on sale of real estate, net of tax			(17,819)	(4,448)
Provision for impairment, net of tax	(14)	855	12,099	29,443
Early extinguishment of debt	1,391		11,982	11,172
Distribution of earnings from investments in real estate partnerships			41,427	40,366
Settlement of derivative instruments			(6,870)	0
Deferred compensation expense			3,551	1,475
Realized and unrealized gain on investments			(3,634)	(1,524)
Changes in assets and liabilities:
Tenant and other receivables			520	(13,326)
Deferred leasing costs			(4,695)	(6,259)
Other assets			(7,182)	(6,565)
Accounts payable and other liabilities			14,886	15,100
Tenants’ security, escrow deposits and prepaid rent			(5,055)	(2,111)
Net cash provided by operating activities			469,356	464,755
Cash flows from investing activities:
Acquisition of operating real estate			(222,230)	(85,766)
Advance deposits paid on acquisition of operating real estate			(600)	(150)
Real estate development and capital improvements			(128,085)	(174,145)
Proceeds from sale of real estate investments			98,006	151,142
Collection of notes receivable			0	15,648
Investments in real estate partnerships			(57,333)	(58,372)
Return of capital from investments in real estate partnerships			46,740	5,488
Dividends on investment securities			400	281
Acquisition of investment securities			(17,955)	(16,946)
Proceeds from sale of investment securities			14,748	15,639
Net cash used in investing activities			(266,309)	(147,181)
Cash flows from financing activities:
Repurchase of common shares in conjunction with equity award plans			(6,165)	(6,772)
Common shares repurchased through share repurchase program			(32,777)	(124,989)
Proceeds from sale of treasury stock			9	99
Distributions to limited partners in consolidated partnerships, net			(2,223)	(3,457)
Distributions to exchangeable operating partnership unit holders			(614)	(582)
Dividends paid to common stockholders			(292,921)	(282,276)
Repayment of fixed rate unsecured notes			(250,000)	(150,000)
Proceeds from issuance of fixed rate unsecured notes, net			723,571	299,511
Proceeds from unsecured credit facilities			450,000	455,000
Repayment of unsecured credit facilities			(710,000)	(370,000)
Proceeds from notes payable			0	1,740
Repayment of notes payable			(55,030)	(113,037)
Scheduled principal payments			(6,960)	(7,767)
Payment of loan costs			(7,019)	(9,448)
Early redemption costs			(10,647)	(10,491)
Net cash used in financing activities			(200,776)	(322,469)
Net increase (decrease) in cash and cash equivalents and restricted cash			2,271	(4,895)
Cash and cash equivalents and restricted cash at beginning of the period			45,190	49,381	$ 49,381
Cash and cash equivalents and restricted cash at end of the period	47,461	44,486	47,461	44,486	45,190
Supplemental disclosure of cash flow information:
Cash paid for interest (net of capitalized interest of $3,089 and $5,820 in 2019 and 2018, respectively)			112,055	104,210
Cash paid for income taxes, net of refunds			778	4,771
Supplemental disclosure of non-cash transactions:
Mortgage loans for the acquisition of real estate			26,152	9,700
Exchangeable operating partnership units issued for acquisition of real estate			25,869
Change in accrued capital expenditures			3,185
Common stock issued under dividend reinvestment plan	345	318	1,085	996
Stock-based compensation capitalized			1,719	2,606
Contributions from limited partners in consolidated partnerships, net			66
Common stock issued for dividend reinvestment in trust			732	627
Contribution of stock awards into trust			2,496	1,244
Distribution of stock held in trust			197	524
Change in fair value of securities			509	5
Partnership Interest [Member]
Cash flows from operating activities:
Net income	57,944	70,534	202,127	172,588
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization			282,639	266,812
Amortization of deferred loan costs and debt premiums			8,533	7,599
(Accretion) and amortization of above and below market lease intangibles, net			(30,196)	(26,031)
Stock-based compensation, net of capitalization			10,716	10,012
Equity in income of investments in real estate partnerships	283	(10,024)	(43,673)	(29,548)
Gain on sale of real estate, net of tax			(17,819)	(4,448)
Provision for impairment, net of tax	(14)	855	12,099	29,443
Early extinguishment of debt	1,391		11,982	11,172
Distribution of earnings from investments in real estate partnerships			41,427	40,366
Settlement of derivative instruments			(6,870)	0
Deferred compensation expense			3,551	1,475
Realized and unrealized gain on investments			(3,634)	(1,524)
Changes in assets and liabilities:
Tenant and other receivables			520	(13,326)
Deferred leasing costs			(4,695)	(6,259)
Other assets			(7,182)	(6,565)
Accounts payable and other liabilities			14,886	15,100
Tenants’ security, escrow deposits and prepaid rent			(5,055)	(2,111)
Net cash provided by operating activities			469,356	464,755
Cash flows from investing activities:
Acquisition of operating real estate			(222,230)	(85,766)
Advance deposits paid on acquisition of operating real estate			(600)	(150)
Real estate development and capital improvements			(128,085)	(174,145)
Proceeds from sale of real estate investments			98,006	151,142
Issuance of notes receivable			0	15,648
Investments in real estate partnerships			(57,333)	(58,372)
Return of capital from investments in real estate partnerships			46,740	5,488
Dividends on investment securities			400	281
Acquisition of investment securities			(17,955)	(16,946)
Proceeds from sale of investment securities			14,748	15,639
Net cash used in investing activities			(266,309)	(147,181)
Cash flows from financing activities:
Repurchase of common shares in conjunction with equity award plans			(6,165)	(6,772)
Common shares repurchased through share repurchase program			(32,777)	(124,989)
Proceeds from sale of treasury stock			9	99
Distributions to limited partners in consolidated partnerships, net			(2,223)	(3,457)
Dividends paid to common stockholders			(293,535)	(282,858)
Repayment of fixed rate unsecured notes			(250,000)	(150,000)
Proceeds from issuance of fixed rate unsecured notes, net			723,571	299,511
Proceeds from unsecured credit facilities			450,000	455,000
Repayment of unsecured credit facilities			(710,000)	(370,000)
Proceeds from notes payable			0	1,740
Repayment of notes payable			(55,030)	(113,037)
Scheduled principal payments			(6,960)	(7,767)
Payment of loan costs			(7,019)	(9,448)
Early redemption costs			(10,647)	(10,491)
Net cash used in financing activities			(200,776)	(322,469)
Net increase (decrease) in cash and cash equivalents and restricted cash			2,271	(4,895)
Cash and cash equivalents and restricted cash at beginning of the period			45,190	49,381	49,381
Cash and cash equivalents and restricted cash at end of the period	$ 47,461	$ 44,486	47,461	44,486	$ 45,190
Supplemental disclosure of cash flow information:
Cash paid for interest (net of capitalized interest of $3,089 and $5,820 in 2019 and 2018, respectively)			112,055	104,210
Cash paid for income taxes, net of refunds			778	4,771
Supplemental disclosure of non-cash transactions:
Mortgage loans for the acquisition of real estate			26,152	9,700
Exchangeable operating partnership units issued for acquisition of real estate			25,869
Change in accrued capital expenditures			3,185
Common stock issued under dividend reinvestment plan			1,085	996
Stock-based compensation capitalized			1,719	2,606
Contributions from limited partners in consolidated partnerships, net			66
Common stock issued for dividend reinvestment in trust			732	627
Contribution of stock awards into trust			2,496	1,244
Distribution of stock held in trust			197	524
Change in fair value of securities			$ 509	$ 5