Consolidated Balance Sheets - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Document Fiscal Year Focus	2016
Real estate investments at cost (notes 1, 2 and 3):
Investments in real estate partnerships (note 4)	$ 296,699	$ 306,206
COMBINED ABOVE-Notes receivable (note 5)	10,481	10,480
Acquired lease intangible assets, less accumulated amortization of $56,695 and $45,639 at December 31, 2016 and 2015, respectively (note 5)	118,831	105,380
Noncontrolling interests (note 9):
Total equity	2,624,502	2,082,620
Parent Company [Member]
Real estate investments at cost (notes 1, 2 and 3):
Land	1,660,424	1,479,814
Buildings and improvements	3,092,197	2,896,396
Properties in development	180,878	169,690
Gross real estate investments at cost	4,933,499	4,545,900
Less: accumulated depreciation	1,124,391	1,043,787
Total Cost Net of Accumulated Depreciation	3,809,108	3,502,113
Investments in real estate partnerships (note 4)	296,699	306,206
Net real estate investments	4,105,807	3,808,319
Cash and cash equivalents	13,256	36,856
Restricted cash	4,623	3,767
Accounts and Notes Receivable, Net	111,722	106,164
Deferred Costs	69,000	66,367
Acquired lease intangible assets, less accumulated amortization of $56,695 and $45,639 at December 31, 2016 and 2015, respectively (note 5)	118,831	105,380
Assets Held-in-trust	28,588	29,093
Other assets	37,079	26,935
Total assets	4,488,906	4,182,881
Liabilities:
Notes payable (note 6)	1,363,925	1,699,771
Unsecured Debt	278,495	164,514
Accounts payable and other liabilities	138,936	164,515
Acquired lease intangible liabilities, less accumulated amortization of $23,538 and $17,555 at December 31, 2016 and 2015, respectively (note 5)	54,180	42,034
Tenants’ security and escrow deposits and prepaid rent	28,868	29,427
Total liabilities	1,864,404	2,100,261
Commitments and contingencies (notes 13 and 14)	0	0
Stockholders’ equity (note 9):
Preferred stock, $0.01 par value per share, 30,000,000 shares authorized; 13,000,000 Series 6 and 7 shares issued and outstanding at December 31, 2013 and December 31, 2012, with liquidation preferences of $25 per share	325,000	325,000
Common stock $0.01 par value per share,150,000,000 shares authorized; 104,497,286 and 97,212,638 shares issued at December 31, 2016 and 2015, respectively	1,045	972
Treasury Stock, Value	17,062	19,658
Additional paid in capital	3,294,923	2,742,508
Accumulated other comprehensive loss	(18,346)	(58,693)
Distributions in excess of net income	(994,259)	(936,020)
Total stockholders’ equity	2,591,301	2,054,109
Noncontrolling interests (note 9):
Noncontrolling Interest in Operating Partnerships	(1,967)	(1,975)
Limited partners’ interests in consolidated partnerships	35,168	30,486
Total noncontrolling interests	33,201	28,511
Total equity	2,624,502	2,082,620
Total liabilities and equity	4,488,906	4,182,881
Partnership Interest [Member]
Real estate investments at cost (notes 1, 2 and 3):
Land	1,660,424	1,479,814
Buildings and improvements	3,092,197	2,896,396
Properties in development	180,878	169,690
Gross real estate investments at cost	4,933,499	4,545,900
Less: accumulated depreciation	1,124,391	1,043,787
Total Cost Net of Accumulated Depreciation	3,809,108	3,502,113
Investments in real estate partnerships (note 4)	296,699	306,206
Net real estate investments	4,105,807	3,808,319
Cash and cash equivalents	13,256	36,856
Restricted cash	4,623	3,767
Accounts and Notes Receivable, Net	111,722	106,164
COMBINED ABOVE-Notes receivable (note 5)	10,481	10,480
Deferred Costs	69,000	66,367
Acquired lease intangible assets, less accumulated amortization of $56,695 and $45,639 at December 31, 2016 and 2015, respectively (note 5)	118,831	105,380
Assets Held-in-trust	28,588	29,093
Other assets	37,079	26,935
Total assets	4,488,906	4,182,881
Liabilities:
Notes payable (note 6)	1,363,925	1,699,771
Unsecured Debt	278,495	164,514
Accounts payable and other liabilities	138,936	164,515
Acquired lease intangible liabilities, less accumulated amortization of $23,538 and $17,555 at December 31, 2016 and 2015, respectively (note 5)	54,180	42,034
Tenants’ security and escrow deposits and prepaid rent	28,868	29,427
Total liabilities	1,864,404	2,100,261
Commitments and contingencies (notes 13 and 14)	0	0
Stockholders’ equity (note 9):
Preferred Units General Partner	325,000	325,000
General partner; 104,497,286 and 97,212,638 units outstanding at December 31, 2016 and 2015, respectively	2,284,647	1,787,802
Limited Partners' Capital Account	(1,967)	(1,975)
Accumulated other comprehensive loss	(18,346)	(58,693)
Total partners’ capital	2,589,334	2,052,134
Noncontrolling interests (note 9):
Limited partners’ interests in consolidated partnerships	35,168	30,486
Total noncontrolling interests	35,168	30,486
Total equity	2,624,502	2,082,620
Total liabilities and equity	$ 4,488,906	$ 4,182,881