Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Real estate investments at cost:
Notes receivable	$ 16,316	$ 15,803
Liabilities:
Notes payable	3,276,888	2,971,715
Unsecured credit facilities	563,380	623,262
Noncontrolling interests:
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest		(6,733,054)
Parent Company [Member]
Real estate investments at cost:
Property, Plant and Equipment, Gross	10,768,379	10,578,430
Properties in development	179,123	314,391
Gross real estate investments at cost	10,947,502	10,892,821
Less: accumulated depreciation	1,394,276	1,339,771
Total Cost Net of Accumulated Depreciation	9,553,226	9,553,050
Properties held for sale	8,742	0
Investments in real estate partnerships	448,257	386,304
Net real estate investments	10,010,225	9,939,354
Cash and cash equivalents	87,904	45,370
Restricted cash	5,732	4,011
Tenant and other receivables, net of allowance for doubtful accounts and straight-line rent reserves of $13,945 and $12,728 at March 31, 2018 and December 31, 2017, respectively	159,587	170,985
Deferred Costs, Leasing, Net	83,638	80,044
Acquired lease intangible assets, less accumulated amortization of $171,114 and $148,280 at March 31, 2018 and December 31, 2017, respectively	455,589	478,826
Other assets	431,181	427,127
Total assets	11,233,856	11,145,717
Liabilities:
Notes payable	3,276,888	2,971,715
Unsecured credit facilities	563,380	623,262
Accounts payable and other liabilities	212,515	234,272
Acquired lease intangible liabilities, less accumulated amortization of $68,123 and $56,550 at March 31, 2018 and December 31, 2017, respectively	527,264	537,401
Tenants’ security, escrow deposits and prepaid rent	48,428	46,013
Total liabilities	4,628,475	4,412,663
Commitments and contingencies	0	0
Stockholders’ equity/Partners' capital:
Common stock, $0.01 par value per share, 220,000,000 shares authorized; 169,408,781 and 171,364,908 shares issued at March 31, 2018 and December 31, 2017, respectively	1,694	1,714
Treasury stock at cost, 372,712 and 366,628 shares held at March 31, 2018 and December 31, 2017, respectively	(18,756)	(18,307)
Additional paid in capital	7,746,427	7,873,104
Accumulated other comprehensive income (loss)	4,764	(6,289)
Distributions in excess of net income	(1,169,828)	(1,158,170)
Total stockholders’ equity	6,564,301	6,692,052
Noncontrolling interests:
Exchangeable operating partnership units, aggregate redemption value of $20,637 and $24,206 at March 31, 2018 and December 31, 2017, respectively	10,847	10,907
Limited partners’ interests in consolidated partnerships	30,233	30,095
Stockholders' Equity Attributable to Noncontrolling Interest	41,080	41,002
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(6,605,381)	(6,733,054)
Total liabilities and equity	11,233,856	11,145,717
Partnership Interest [Member]
Real estate investments at cost:
Property, Plant and Equipment, Gross	10,768,379	10,578,430
Properties in development	179,123	314,391
Gross real estate investments at cost	10,947,502	10,892,821
Less: accumulated depreciation	1,394,276	1,339,771
Total Cost Net of Accumulated Depreciation	9,553,226	9,553,050
Properties held for sale	8,742	0
Investments in real estate partnerships	448,257	386,304
Net real estate investments	10,010,225	9,939,354
Cash and cash equivalents	87,904	45,370
Restricted cash	5,732	4,011
Tenant and other receivables, net of allowance for doubtful accounts and straight-line rent reserves of $13,945 and $12,728 at March 31, 2018 and December 31, 2017, respectively	159,587	170,985
Deferred Costs, Leasing, Net	83,638	80,044
Acquired lease intangible assets, less accumulated amortization of $171,114 and $148,280 at March 31, 2018 and December 31, 2017, respectively	455,589	478,826
Other assets	431,181	427,127
Total assets	11,233,856	11,145,717
Liabilities:
Notes payable	3,276,888	2,971,715
Unsecured credit facilities	563,380	623,262
Accounts payable and other liabilities	212,515	234,272
Acquired lease intangible liabilities, less accumulated amortization of $68,123 and $56,550 at March 31, 2018 and December 31, 2017, respectively	527,264	537,401
Tenants’ security, escrow deposits and prepaid rent	48,428	46,013
Total liabilities	4,628,475	4,412,663
Commitments and contingencies	0	0
Stockholders’ equity/Partners' capital:
General partner; 169,408,781 and 171,364,908 units outstanding at March 31, 2018 and December 31, 2017, respectively	6,559,537	6,698,341
Limited partners; 349,902 units outstanding at March 31, 2018 and December 31, 2017	10,847	10,907
Accumulated other comprehensive income (loss)	4,764	(6,289)
Total partners’ capital	6,575,148	6,702,959
Noncontrolling interests:
Limited partners’ interests in consolidated partnerships	30,233	30,095
Total noncontrolling interests	30,233	30,095
Total equity	6,605,381	6,733,054
Total liabilities and equity	$ 11,233,856	$ 11,145,717