Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Parent Company [Member]
Real Estate Investment Property, at Cost [Abstract]
Gross real estate investments at cost	$ 10,875,058	$ 10,863,162
Less: accumulated depreciation	1,605,681	1,535,444
Total Cost Net of Accumulated Depreciation	9,269,377	9,327,718
Investments in real estate partnerships	456,733	463,001
Real Estate Held-for-sale	15,275	60,516
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	42,784	45,190
Restricted cash	3,305	2,658
Tenant and other receivables	160,635	172,359
Deferred Costs, Leasing, Net	82,477	84,983
Acquired lease intangible assets, less accumulated amortization of $225,693 and $219,689 at March 31, 2019 and December 31, 2018, respectively	280,613	387,069
Other assets	412,851	403,827
Total assets	11,017,604	10,944,663
Liabilities:
Notes payable	3,009,886	3,006,478
Unsecured credit facilities	673,852	708,734
Accounts payable and other liabilities	183,983	224,807
Acquired lease intangible liabilities, less accumulated amortization of $99,163 and $92,746 at March 31, 2019 and December 31, 2018, respectively	475,065	496,726
Operating Lease, Liability	225,122	0
Tenants’ security, escrow deposits and prepaid rent	46,923	57,750
Total liabilities	4,614,831	4,494,495
Commitments and contingencies	0	0
Stockholders’ equity/Partners' capital:
Common stock, $0.01 par value per share, 220,000,000 shares authorized; 167,517,243 and 167,904,593 shares issued at March 31, 2019 and December 31, 2018, respectively	1,675	1,679
Treasury stock at cost, 410,963 and 390,163 shares held at March 31, 2019 and December 31, 2018, respectively	(21,226)	(19,834)
Additional paid-in-capital	7,639,353	7,672,517
Accumulated other comprehensive loss	(6,096)	(927)
Distributions in excess of net income	(1,263,011)	(1,255,465)
Total stockholders’ equity	6,350,695	6,397,970
Noncontrolling interests:
Exchangeable operating partnership units, aggregate redemption value of $23,615 and $20,532 at March 31, 2019 and December 31, 2018, respectively	10,641	10,666
Limited partners’ interests in consolidated partnerships	41,437	41,532
Stockholders' Equity Attributable to Noncontrolling Interest	52,078	52,198
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(6,402,773)	(6,450,168)
Total liabilities and equity	11,017,604	10,944,663
Operating Lease, Right-of-Use Asset	296,859	0
Partnership Interest [Member]
Real Estate Investment Property, at Cost [Abstract]
Gross real estate investments at cost	10,875,058	10,863,162
Less: accumulated depreciation	1,605,681	1,535,444
Total Cost Net of Accumulated Depreciation	9,269,377	9,327,718
Investments in real estate partnerships	456,733	463,001
Real Estate Held-for-sale	15,275	60,516
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents	42,784	45,190
Restricted cash	3,305	2,658
Tenant and other receivables	160,635	172,359
Deferred Costs, Leasing, Net	82,477	84,983
Acquired lease intangible assets, less accumulated amortization of $225,693 and $219,689 at March 31, 2019 and December 31, 2018, respectively	280,613	387,069
Other assets	412,851	403,827
Total assets	11,017,604	10,944,663
Liabilities:
Notes payable	3,009,886	3,006,478
Unsecured credit facilities	673,852	708,734
Accounts payable and other liabilities	183,983	224,807
Acquired lease intangible liabilities, less accumulated amortization of $99,163 and $92,746 at March 31, 2019 and December 31, 2018, respectively	475,065	496,726
Operating Lease, Liability	225,122	0
Tenants’ security, escrow deposits and prepaid rent	46,923	57,750
Total liabilities	4,614,831	4,494,495
Commitments and contingencies	0	0
Stockholders’ equity/Partners' capital:
General partner; 167,517,243 and 167,904,593 units outstanding at March 31, 2019 and December 31, 2018, respectively	6,356,791	6,398,897
Limited partners; 349,902 units outstanding at March 31, 2019 and December 31, 2018	10,641	10,666
Accumulated other comprehensive loss	(6,096)	(927)
Total partners’ capital	6,361,336	6,408,636
Noncontrolling interests:
Limited partners’ interests in consolidated partnerships	41,437	41,532
Total equity	6,402,773	6,450,168
Total liabilities and equity	11,017,604	10,944,663
Operating Lease, Right-of-Use Asset	$ 296,859	$ 0