Retail Properties of America (RPAI) 10-Q 2 May 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 27, 2018
Entity Information [Line Items]
Entity Registrant Name	RETAIL PROPERTIES OF AMERICA, INC.
Entity Central Index Key	1,222,840
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		219,488,688

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Investment properties:
Land	$ 1,042,260	$ 1,066,705
Building and other improvements	3,553,298	3,686,200
Developments in progress	19,805	33,022
Gross investment properties	4,615,363	4,785,927
Less accumulated depreciation	(1,210,147)	(1,215,990)
Net investment properties	3,405,216	3,569,937
Cash and cash equivalents	33,533	25,185
Accounts and notes receivable (net of allowances of $6,675 and $6,567, respectively)	66,893	71,678
Acquired lease intangible assets, net	116,141	122,646
Assets associated with investment properties held for sale	68,799	3,647
Other assets, net	67,139	125,171
Total assets	3,757,721	3,918,264
Liabilities:
Mortgages payable, net	275,316	287,068
Unsecured notes payable, net	695,902	695,748
Unsecured term loans, net	547,629	547,270
Unsecured revolving line of credit	91,000	216,000
Accounts payable and accrued expenses	53,270	82,698
Distributions payable	36,353	36,311
Acquired lease intangible liabilities, net	94,911	97,971
Liabilities associated with investment properties held for sale	2,673	0
Other liabilities	66,023	69,498
Total liabilities	1,863,077	2,032,564
Commitments and contingencies (Note 14)
Equity:
Preferred stock	0	0
Additional paid-in capital	4,575,191	4,574,428
Accumulated distributions in excess of earnings	(2,684,606)	(2,690,021)
Accumulated other comprehensive income	3,840	1,074
Total equity	1,894,644	1,885,700
Total liabilities and equity	3,757,721	3,918,264
Class A common stock
Equity:
Class A common stock	$ 219	$ 219

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (parenthetical) - USD ($) shares in Thousands, $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Accounts and notes receivable, allowances (in dollars)	$ 6,675	$ 6,567
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	10,000	10,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Class A common stock
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	475,000	475,000
Common stock, shares issued	219,489	219,237
Common stock, shares outstanding	219,489	219,237

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Other Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Rental income	$ 94,455	$ 109,974
Tenant recovery income	28,090	30,786
Other property income	2,297	2,933
Total revenues	124,842	143,693
Expenses
Operating expenses	20,255	21,864
Real estate taxes	20,468	21,879
Depreciation and amortization	45,228	53,474
Provision for impairment of investment properties	592	0
General and administrative expenses	12,495	11,213
Total expenses	99,038	108,430
Operating income	25,804	35,263
Interest expense	(18,765)	(85,532)
Other income, net	222	5
Income (loss) from continuing operations	7,261	(50,264)
Gain on sales of investment properties	34,519	41,164
Net income (loss)	41,780	(9,100)
Preferred stock dividends	0	(2,362)
Net income (loss) attributable to common shareholders	$ 41,780	$ (11,462)
Earnings (loss) per common share – basic and diluted
Net income (loss) per common share attributable to common shareholders	$ 0.19	$ (0.05)
Net income (loss)	$ 41,780	$ (9,100)
Other comprehensive income:
Net unrealized gain on derivative instruments (Note 9)	2,754	632
Comprehensive income (loss) attributable to the Company	$ 44,534	$ (8,468)
Weighted average number of common shares outstanding – basic	218,849	236,294
Weighted average number of common shares outstanding – diluted	219,403	236,294

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Equity - USD ($) shares in Thousands, $ in Thousands	Total	Preferred stock	Preferred stock7.00% Series A cumulative redeemable preferred stock	Common stockClass A common stock	Additional paid-in capital	Accumulated distributions in excess of earnings	Accumulated other comprehensive income	Total shareholders' equity
Balance at Dec. 31, 2016			$ 5	$ 237	$ 4,927,155	$ (2,776,033)	$ 722	$ 2,152,086
Balance (in shares) at Dec. 31, 2016			5,400	236,770
Increase (decrease) in shareholders' equity
Net income (loss)	$ (9,100)					(9,100)		(9,100)
Other comprehensive income							632	632
Distributions declared to preferred shareholders						(2,362)		(2,362)
Distributions declared to common shareholders						(39,235)		(39,235)
Issuance of restricted shares (in shares)				206
Stock-based compensation expense					1,793			1,793
Shares withheld for employee taxes					(1,333)			(1,333)
Shares withheld for employee taxes (in shares)				(88)
Balance at Mar. 31, 2017			$ 5	$ 237	4,927,615	(2,826,730)	1,354	2,102,481
Balance (in shares) at Mar. 31, 2017			5,400	236,888
Increase (decrease) in shareholders' equity
Cumulative effect of accounting change						(12)	12
Balance at Dec. 31, 2017	1,885,700	$ 0		$ 219	4,574,428	(2,690,021)	1,074	1,885,700
Balance (in shares) at Dec. 31, 2017		0		219,237
Increase (decrease) in shareholders' equity
Net income (loss)	41,780					41,780		41,780
Other comprehensive income							2,754	2,754
Distributions declared to common shareholders						(36,353)		(36,353)
Issuance of common stock (in shares)				59
Issuance of restricted shares (in shares)				305
Stock-based compensation expense					2,133			2,133
Shares withheld for employee taxes					(1,370)			(1,370)
Shares withheld for employee taxes (in shares)				(112)
Balance at Mar. 31, 2018	$ 1,894,644	$ 0		$ 219	$ 4,575,191	$ (2,684,606)	$ 3,840	$ 1,894,644
Balance (in shares) at Mar. 31, 2018		0		219,489

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Equity (parenthetical)	3 Months Ended
	Mar. 31, 2017$ / shares
Distributions declared to preferred shareholders (in dollars per share)	$ 0.4375
Distributions declared to common shareholders (in dollars per share)	$ 0.165625

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Cash flows from operating activities:
Net income (loss)	$ 41,780	$ (9,100)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	45,228	53,474
Provision for impairment of investment properties	592	0
Gain on sales of investment properties	(34,519)	(41,164)
Amortization of loan fees and debt premium and discount, net	940	4,965
Amortization of stock-based compensation	2,133	1,793
Premium paid in connection with defeasance of mortgages payable	0	59,968
Debt prepayment fees	974	2,284
Payment of leasing fees and inducements	(2,147)	(2,152)
Changes in accounts receivable, net	2,879	6,534
Changes in accounts payable and accrued expenses, net	(25,202)	(24,311)
Changes in other operating assets and liabilities, net	3,530	8,237
Other, net	(2,023)	651
Net cash provided by operating activities	34,165	61,179
Cash flows from investing activities:
Purchase of investment properties	0	(93,752)
Capital expenditures and tenant improvements	(11,692)	(12,432)
Proceeds from sales of investment properties	112,214	104,527
Investment in developments in progress	(2,848)	(1,610)
Net cash provided by (used in) investing activities	97,674	(3,267)
Cash flows from financing activities:
Principal payments on mortgages payable	(11,788)	(20,588)
Proceeds from unsecured term loans	0	200,000
Proceeds from unsecured revolving line of credit	55,000	389,000
Repayments of unsecured revolving line of credit	(180,000)	(112,000)
Payment of loan fees and deposits	0	(10)
Debt prepayment fees	(974)	(2,284)
Purchase of U.S. Treasury securities in connection with defeasance of mortgages payable	0	(439,403)
Distributions paid	(36,311)	(41,584)
Other, net	(1,370)	(1,333)
Net cash used in financing activities	(175,443)	(28,202)
Net (decrease) increase in cash, cash equivalents and restricted cash	(43,604)	29,710
Cash, cash equivalents and restricted cash, at beginning of period	86,335	82,349	$ 82,349
Cash, cash equivalents and restricted cash, at end of period	42,731	112,059	86,335
Supplemental cash flow disclosure, including non-cash activities:
Cash paid for interest, net of interest capitalized	17,636	19,868
Distributions payable	36,353	39,235	36,311
Accrued capital expenditures and tenant improvements	6,581	7,649
Accrued leasing fees and inducements	444	975
Accrued redevelopment costs	1,129	5,282
Developments in progress placed in service	6,819	0
U.S. Treasury securities transferred in connection with defeasance of mortgages payable	0	439,403
Defeasance of mortgages payable	0	379,435
Purchase of investment properties (after credits at closing):
Net investment properties	0	(95,622)
Accounts receivable, acquired lease intangibles and other assets	0	(7,550)
Accounts payable, acquired lease intangibles and other liabilities	0	6,896
Deferred gain	0	2,524
Purchase of investment properties (after credits at closing)	0	(93,752)
Proceeds from sales of investment properties:
Net investment properties	80,460	64,519
Accounts receivable, acquired lease intangibles and other assets	3,403	841
Accounts payable, acquired lease intangibles and other liabilities	(6,168)	(511)
Deferred gain	0	(1,486)
Gain on sales of investment properties	34,519	41,164
Proceeds from sales of investment properties	112,214	104,527
Reconciliation of cash, cash equivalents and restricted cash reported on the Company’s condensed consolidated balance sheets to such amounts shown in the Company’s condensed consolidated statements of cash flows:
Cash and cash equivalents, at beginning of period	25,185	53,119	53,119
Restricted cash, at beginning of period (included in “Other assets, net”)	61,150	29,230	29,230
Cash, cash equivalents and restricted cash, at beginning of period	86,335	82,349	82,349
Cash and cash equivalents, at end of period	33,533	40,274	25,185
Restricted cash, at end of period (included in “Other assets, net”)	9,198	71,785	61,150
Cash, cash equivalents and restricted cash, at end of period	$ 42,731	$ 112,059	$ 86,335

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	ORGANIZATION AND BASIS OF PRESENTATION Retail Properties of America, Inc. (the Company) was formed on March 5, 2003 and its primary purpose is to own and operate high quality, strategically located shopping centers in the United States. The Company has elected to be taxed as a real estate investment trust (REIT) under the Internal Revenue Code of 1986, as amended (the Code). The Company believes it qualifies for taxation as a REIT and, as such, the Company generally will not be subject to U.S. federal income tax on taxable income that is distributed to its shareholders. If the Company fails to qualify as a REIT in any taxable year, the Company will be subject to U.S. federal income tax on its taxable income. Even if the Company qualifies for taxation as a REIT, the Company may be subject to certain state and local taxes on its income, property or net worth and U.S. federal income and excise taxes on its undistributed income. The Company has one wholly-owned subsidiary that has jointly elected to be treated as a taxable REIT subsidiary (TRS) and is subject to U.S. federal, state and local income taxes at regular corporate tax rates. The income tax expense incurred by the TRS did not have a material impact on the Company’s accompanying condensed consolidated financial statements. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions. These estimates and assumptions affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting periods. For example, significant estimates and assumptions have been made with respect to useful lives of assets, capitalization of development costs, fair value measurements, provision for impairment, including estimates of holding periods, capitalization rates and discount rates (where applicable), provision for income taxes, recoverable amounts of receivables, deferred taxes and initial valuations and related amortization periods of deferred costs and intangibles, particularly with respect to property acquisitions. Actual results could differ from these estimates. All share amounts and dollar amounts in this Quarterly Report on Form 10-Q, including the condensed consolidated financial statements and notes thereto, are stated in thousands with the exception of per share amounts and per square foot amounts. The accompanying condensed consolidated financial statements include the accounts of the Company, as well as all wholly-owned subsidiaries and any consolidated variable interest entities (VIEs). All intercompany balances and transactions have been eliminated in consolidation. Wholly-owned subsidiaries generally consist of limited liability companies, limited partnerships and statutory trusts. The Company’s property ownership as of March 31, 2018 is summarized below: Wholly-owned (a) Retail operating properties 106 Redevelopment properties 1 (a) Excludes (i) Schaumburg Towers, the Company’s one remaining office complex which is classified as held for sale, (ii) one property where the Company has begun activities in anticipation of future redevelopment and (iii) the redevelopment portion of Circle East, formerly known as Towson Circle, which has been combined with the Company’s neighboring retail operating property formerly known as Towson Square. This combination reduced the Company’s redevelopment property count by one .

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Refer to the Company’s 2017 Annual Report on Form 10-K for a summary of its significant accounting policies. Except as disclosed below, there have been no changes to the Company’s significant accounting policies in the three months ended March 31, 2018 . Recently Adopted Accounting Pronouncements Effective January 1, 2018, the Company adopted Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers , on a modified retrospective basis. This new guidance replaces existing revenue recognition standards. The core principle of this standard is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Substantially all of the Company’s revenue follows the existing leasing guidance and is not impacted by the adoption of this standard, however, the sale of investment property is required to follow the new guidance as well as ASU 2017-05, Other Income–Gains and Losses from the Derecognition of Nonfinancial Assets discussed below. The sale of investment property is reported as “gain on sales of investment properties” in the accompanying condensed consolidated statements of operations and other comprehensive income (loss) and further discussed in Note 4 – Dispositions. The adoption of ASU 2014-09, Revenue from Contracts with Customers , did not have a material effect on the Company’s condensed consolidated financial statements as substantially all of its revenue falls outside of the scope of this guidance. Effective January 1, 2018, the Company adopted ASU 2017-05, Other Income–Gains and Losses from the Derecognition of Nonfinancial Assets , on a modified retrospective basis. This new pronouncement, which adds guidance for partial sales of nonfinancial assets and clarifies the scope of Subtopic 610-20, Gains and Losses from the Derecognition of Nonfinancial Assets , applies to the derecognition of all nonfinancial assets (including real estate) for which the counterparty is not a customer. The sale of investment property is reported as “gain on sales of investment properties” in the accompanying condensed consolidated statements of operations and other comprehensive income (loss) and further discussed in Note 4 – Dispositions. The adoption of this pronouncement did not have a material effect on the Company’s condensed consolidated financial statements as the adoption of the new guidance did not result in a change to the timing or amount of gain recognized upon disposition as compared to the previous guidance. Effective January 1, 2018, the Company adopted ASU 2016-01, Financial Instruments – Overall , on a prospective basis. This new guidance requires companies to disclose the fair value of financial assets and financial liabilities measured at amortized cost in accordance with the exit price notion, which is consistent with the Company’s existing practices, and no longer requires disclosure of the methods and significant assumptions used, including any changes, to estimate fair value. In addition, companies are required to disclose all financial assets and financial liabilities grouped by (i) measurement category and (ii) form of financial instrument. The adoption of this pronouncement did not have a material effect on the Company’s condensed consolidated financial statements. The Company elected to early adopt ASU 2017-12, Derivatives and Hedging , as of January 1, 2018. This new guidance amends the designation and measurement guidance for qualifying hedging relationships and the presentation of hedge results in an entity’s financial statements. It also eliminates the requirement to separately measure and report hedge ineffectiveness. Entities are now required to present the earnings effect of the hedging instrument in the same income statement line item in which they report the earnings effect of the hedged item. In addition, entities may perform the initial quantitative assessment of hedge effectiveness at any time after hedge designation, but no later than the first quarterly effectiveness testing date, and subsequent assessments of hedge effectiveness may be performed qualitatively unless facts and circumstances change. Disclosure requirements have been modified to include a tabular disclosure related to the effect of hedging instruments on the income statement and the requirement to disclose the ineffective portion of the change in fair value of such instruments has been eliminated. The adoption of this pronouncement resulted in a cumulative effect adjustment of $12 to accumulated other comprehensive income and accumulated distributions in excess of earnings related to eliminating the separate measurement of ineffectiveness. The amended presentation and disclosure guidance is required only prospectively. Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (FASB) issued ASU 2016-02, Leases . This new guidance is effective January 1, 2019, with early adoption permitted, and will require lessees to recognize a liability to make lease payments and a right-of-use (ROU) asset, initially measured at the present value of lease payments, for both operating and financing leases. For leases with a term of 12 months or less, lessees will be permitted to make an accounting policy election by class of underlying asset to not recognize lease liabilities and lease assets. Upon adoption, the Company will recognize a lease liability and an ROU asset for operating leases where it is the lessee, such as ground leases and office leases. The Company is in the process of evaluating the inputs required to calculate the amounts that will be recorded on its balance sheet for each lease. For leases with a term of 12 months or less, the Company expects to make an accounting policy election by class of underlying asset to not recognize lease liabilities and lease assets. Under this new pronouncement, lessor accounting for lease components will be largely unchanged from existing GAAP. Only incremental direct leasing costs may be capitalized under the new guidance, which is consistent with the Company’s existing policies. The pronouncement allows some optional practical expedients. The Company expects to adopt this new guidance on January 1, 2019 and will continue to evaluate the impact of this guidance until it becomes effective. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses . This new guidance is effective January 1, 2020, with early adoption permitted beginning January 1, 2019, and replaces the current incurred loss impairment methodology with a methodology that reflects expected credit losses. Financial assets that are measured at amortized cost will be required to be presented at the net amount expected to be collected with an allowance for credit losses deducted from the amortized cost basis. In addition, an entity must consider broader information in developing its expected credit loss estimate, including the use of forecasted information. Generally, the pronouncement requires a modified retrospective method of adoption. The Company will continue to evaluate the impact of this guidance until it becomes effective.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Acquisitions	ACQUISITIONS The Company did not acquire any properties during the three months ended March 31, 2018. The Company closed on the following acquisitions during the three months ended March 31, 2017: Date Property Name Metropolitan Property Type Square Footage Acquisition Price January 13, 2017 Main Street Promenade (a) Chicago Multi-tenant retail 181,600 $ 88,000 January 25, 2017 Boulevard at the Capital Centre – Fee Interest Washington, D.C. Fee interest (b) — 2,000 February 24, 2017 One Loudoun Downtown – Phase II Washington, D.C. Additional phase of multi-tenant retail (c) 15,900 4,128 197,500 $ 94,128 (d) (a) This property was acquired through two consolidated VIEs and used to facilitate an Internal Revenue Code Section 1031 tax-deferred exchange (1031 Exchange). (b) The wholly-owned multi-tenant retail operating property located in Largo, Maryland was previously subject to an approximately 70 acre long-term ground lease with a third party. The Company completed a transaction whereby it received the fee interest in approximately 50 acres of the underlying land in exchange for which (i) the Company paid $1,939 and (ii) the term of the ground lease with respect to the remaining approximately 20 acres was shortened to nine months . The Company derecognized building and improvements of $11,347 related to the remaining ground lease, recognized the fair value of land received of $15,200 and recorded a deferred gain of $2,524 as of March 31, 2017, which was recognized during the three months ended December 31, 2017 upon the expiration of the ground lease on approximately 20 acres. The total number of properties in the Company’s portfolio was not affected by this transaction. (c) The Company acquired an additional phase at its One Loudoun Downtown multi-tenant retail operating property, which was accounted for as an asset acquisition. The total number of properties in the Company’s portfolio was not affected by this transaction. (d) Acquisition price does not include capitalized closing costs and adjustments totaling $2,394 . The following table summarizes the acquisition date values, before prorations, the Company recorded in conjunction with the acquisitions discussed above: Three Months Ended March 31, 2017 Land $ 19,926 Building and other improvements, net 75,696 Acquired lease intangible assets (a) 7,343 Acquired lease intangible liabilities (b) (5,367 ) Other liabilities (1,076 ) Net assets acquired $ 96,522 (a) The weighted average amortization period for acquired lease intangible assets is six years for acquisitions completed during the three months ended March 31, 2017. (b) The weighted average amortization period for acquired lease intangible liabilities is 13 years for acquisitions completed during the three months ended March 31, 2017. The above acquisitions were funded using a combination of available cash on hand, proceeds from dispositions and proceeds from the Company’s unsecured revolving line of credit. All of the acquisitions completed during 2017 were considered asset acquisitions and, as such, transaction costs were capitalized upon closing. Variable Interest Entities During the three months ended March 31, 2017 , the Company entered into an agreement with a qualified intermediary related to a 1031 Exchange. The Company loaned $87,452 to the VIEs to acquire Main Street Promenade on January 13, 2017. The 1031 Exchange was completed during the year ended December 31, 2017 and, in accordance with applicable provisions of the Code, within 180 days after the acquisition date of the property. At the completion of the 1031 Exchange, the sole membership interests of the VIEs were assigned to the Company in satisfaction of the outstanding loan, resulting in the entities being wholly owned by the Company and no longer considered VIEs. Prior to the completion of the 1031 Exchange, the Company was deemed to be the primary beneficiary of each VIE as it had the ability to direct the activities of the VIEs that most significantly impact their economic performance and had all of the risks and rewards of ownership. Accordingly, the Company consolidated the VIEs. No value or income was attributed to the noncontrolling interest. The assets of the VIEs consisted of the investment property, Main Street Promenade, which was operated by the Company.

Dispositions

Dispositions	3 Months Ended
	Mar. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Dispositions	DISPOSITIONS On January 1, 2018, the Company adopted ASU 2014-09, Revenue from Contracts with Customers and ASU 2017-05, Other Income–Gains and Losses from the Derecognition of Nonfinancial Assets on a modified retrospective basis. The dispositions completed during the three months ended March 31, 2018 were not considered to be contracts with customers as defined in ASU 2014-09, Revenue from Contracts with Customers , as they are not considered an output of the Company’s ordinary business activities. Rather, the dispositions follow the new guidance of ASU 2017-05, Other Income–Gains and Losses from the Derecognition of Nonfinancial Assets . The adoption on a modified retrospective basis requires the guidance and related disclosure requirements of ASU 2017-05 to be followed for contracts related to the sale of investment properties completed during the three months ended March 31, 2018 . Disclosures related to periods prior to January 1, 2018 for the sale of investment properties are not impacted by the adoption. Under the new guidance, derecognition of nonfinancial assets and in substance nonfinancial assets, including real estate, and the related gains on sale of investment properties are recognized when (i) the parties to the sale contract have approved the contract and are committed to perform their respective obligations; (ii) the Company can identify each party’s rights regarding the property transferred; (iii) the Company can identify the payment terms for the property transferred; (iv) the contract has commercial substance (that is, the risk, timing or amount of the entity’s future cash flows is expected to change as a result of the contract); and (v) the Company has satisfied its performance obligations by transferring control of the property. Typically, the timing of payment and satisfaction of performance obligations occur simultaneously on the disposition date upon transfer of the property’s ownership. The Company closed on the following dispositions during the three months ended March 31, 2018: Date Property Name Property Type Square Footage Consideration Aggregate Proceeds, Net (a) Gain January 19, 2018 Crown Theater Single-user retail 74,200 $ 6,900 $ 6,350 $ 2,952 February 15, 2018 Cranberry Square Multi-tenant retail 195,200 23,500 23,163 10,174 March 7, 2018 Rite Aid Store (Eckerd)–Crossville, TN Single-user retail 13,800 1,800 1,768 157 March 20, 2018 Home Depot Plaza (b) Multi-tenant retail 135,600 16,250 15,873 — March 21, 2018 Governor's Marketplace Multi-tenant retail 243,100 23,500 20,993 7,429 March 28, 2018 Stony Creek I & Stony Creek II (c) Multi-tenant retail 204,800 32,800 32,078 11,628 866,700 $ 104,750 $ 100,225 $ 32,340 (a) Aggregate proceeds are net of transaction costs and exclude $169 of condemnation proceeds, which did not result in any additional gain recognition. (b) The Company repaid a $10,750 mortgage payable in connection with the disposition of the property. (c) The terms of the disposition of Stony Creek I and Stony Creek II were negotiated as a single transaction. During the three months ended March 31, 2018 , the Company also received net proceeds of $11,820 and recognized a gain of $2,179 in connection with the sale of air rights at Circle East. The aggregate proceeds, net of closing costs, from the property dispositions and other transactions during the three months ended March 31, 2018 totaled $112,214 , with aggregate gains of $34,519 . Subsequent to March 31, 2018 , the Company sold CVS Pharmacy – Lawton, OK, a 10,900 square foot single-user retail operating property, for consideration of $1,600 . The Company closed on the following dispositions during the three months ended March 31, 2017: Date Property Name Property Type Square Footage Consideration Aggregate Proceeds, Net (a) Gain January 27, 2017 Rite Aid Store (Eckerd), Culver Rd. – Rochester, NY Single-user retail 10,900 $ 500 $ 332 $ — February 21, 2017 Shoppes at Park West (b) Multi-tenant retail 63,900 15,383 15,261 7,569 March 7, 2017 CVS Pharmacy – Sylacauga, AL (b) Single-user retail 10,100 3,700 3,348 1,651 March 8, 2017 Rite Aid Store (Eckerd) – Kill Devil Hills, NC (b) Single-user retail 13,800 4,297 4,134 1,857 March 15, 2017 Century III Plaza – Home Depot (b) (c) Single-user parcel 131,900 17,519 17,344 4,487 March 16, 2017 Village Shoppes at Gainesville Multi-tenant retail 229,500 41,750 41,380 14,107 March 24, 2017 Northwood Crossing (b) Multi-tenant retail 160,000 22,850 22,723 10,007 620,100 $ 105,999 $ 104,522 $ 39,678 (a) Aggregate proceeds are net of transaction costs. (b) As of March 31, 2017, the following disposition proceeds were temporarily restricted related to 1031 Exchanges and are included in “Other assets, net” in the accompanying condensed consolidated balance sheets: Property Name Proceeds Temporarily Restricted Shoppes at Park West $ 15,272 CVS Pharmacy – Sylacauga, AL 3,332 Rite Aid Store (Eckerd) – Kill Devil Hills, NC 4,114 Century III Plaza – Home Depot 17,031 Northwood Crossing 22,719 $ 62,468 (c) The Company disposed of the Home Depot parcel at Century III Plaza, an existing 284,100 square foot multi-tenant retail operating property. The remaining portion of Century III Plaza was classified as held for sale as of March 31, 2017 and was sold on December 15, 2017. During the three months ended March 31, 2017, the Company also received proceeds of $5 and recognized a gain of $1,486 as a result of the receipt of the escrow related to the disposition of Maple Tree Place on August 12, 2016. The aggregate proceeds, net of closing costs, from the property dispositions and receipt of the escrow during the three months ended March 31, 2017 totaled $104,527 , with aggregate gains of $41,164 . None of the dispositions completed during the three months ended March 31, 2018 and 2017 qualified for discontinued operations treatment and none are considered individually significant. As of March 31, 2018 , the Company had entered into a contract to sell Schaumburg Towers, an 895,400 square foot office complex located in Schaumburg, Illinois. This property qualified for held for sale accounting treatment upon meeting all applicable GAAP criteria during the quarter ended March 31, 2018 , at which time depreciation and amortization were ceased. In addition, the assets and liabilities associated with this property are separately classified as held for sale in the accompanying condensed consolidated balance sheet as of March 31, 2018 . Crown Theater was classified as held for sale as of December 31, 2017 and was sold during the three months ended March 31, 2018 . The following table presents the assets and liabilities associated with the investment properties classified as held for sale: March 31, 2018 December 31, 2017 Assets Land, building and other improvements $ 61,638 $ 2,791 Less accumulated depreciation — (27 ) Net investment properties 61,638 2,764 Other assets 7,161 883 Assets associated with investment properties held for sale $ 68,799 $ 3,647 Liabilities Other liabilities $ 2,673 $ — Liabilities associated with investment properties held for sale $ 2,673 $ —

Equity Compensation Plans

Equity Compensation Plans	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Compensation Plans	EQUITY COMPENSATION PLANS The Company’s 2014 Long-Term Equity Compensation Plan, subject to certain conditions, authorizes the issuance of incentive and non-qualified stock options, restricted stock and restricted stock units, stock appreciation rights and other similar awards as well as cash-based awards to the Company’s employees, non-employee directors, consultants and advisors in connection with compensation and incentive arrangements that may be established by the Company’s board of directors or executive management. The following table summarizes the Company’s unvested restricted shares as of and for the three months ended March 31, 2018 : Unvested Restricted Shares Weighted Average Grant Date Fair Value per Restricted Share Balance as of January 1, 2018 496 $ 14.81 Shares granted (a) 305 $ 13.02 Shares vested (256 ) $ 15.32 Balance as of March 31, 2018 (b) 545 $ 13.57 (a) Shares granted vest over periods ranging from 0.9 years to three years in accordance with the terms of applicable award agreements. (b) As of March 31, 2018 , total unrecognized compensation expense related to unvested restricted shares was $4,208 , which is expected to be amortized over a weighted average term of 1.6 years . The following table summarizes the Company’s unvested performance restricted stock units (RSUs) as of and for the three months ended March 31, 2018 : Unvested RSUs Weighted Average Grant Date Fair Value per RSU RSUs eligible for future conversion as of January 1, 2018 555 $ 14.60 RSUs granted (a) 291 $ 14.36 Conversion of RSUs to common stock and restricted shares (b) (141 ) $ 14.10 RSUs ineligible for conversion (56 ) $ 15.36 RSUs eligible for future conversion as of March 31, 2018 (c) 649 $ 14.54 (a) Assumptions and inputs as of the grant dates included a weighted average risk-free interest rate of 2.04% , the Company’s historical common stock performance relative to the peer companies within the National Association of Real Estate Investment Trusts (NAREIT) Shopping Center Index and the Company’s weighted average common stock dividend yield of 5.00% . Subject to continued employment, in 2021, following the performance period which concludes on December 31, 2020, one-third of the RSUs that are earned will convert into shares of common stock and two-thirds will convert into restricted shares with a one year vesting term. (b) On February 5, 2018, 141 RSUs converted into 42 shares of common stock and 65 restricted shares that will vest on December 31, 2018, subject to continued employment through such date, after applying a conversion rate of 76% based upon the Company’s Total Shareholder Return (TSR) relative to the TSRs of its peer companies, for the performance period that concluded on December 31, 2017. An additional 16 shares of common stock were also issued representing the dividends that would have been paid on the earned awards during the performance period. (c) As of March 31, 2018 , total unrecognized compensation expense related to unvested RSUs was $6,294 , which is expected to be amortized over a weighted average term of 2.9 years . During the three months ended March 31, 2018 and 2017 , the Company recorded compensation expense of $2,133 and $1,793 , respectively, related to the amortization of unvested restricted shares and RSUs. Included within the amortization of stock-based compensation expense recorded during the three months ended March 31, 2018 is compensation expense of $330 related to the accelerated vesting of 23 restricted shares and remaining amortization related to the 29 RSUs that remain eligible for future conversion in conjunction with the departure of the Company’s former Executive Vice President, General Counsel and Secretary. The total fair value of restricted shares vested during the three months ended March 31, 2018 was $3,161 . Prior to 2013, non-employee directors had been granted options to acquire shares under the Company’s Third Amended and Restated Independent Director Stock Option and Incentive Plan. As of March 31, 2018 , options to purchase 38 shares of common stock remained outstanding and exercisable. The Company did not grant any options in 2018 or 2017 and did not record any compensation expense related to stock options during the three months ended March 31, 2018 and 2017 .

Mortgages Payable

Mortgages Payable	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Mortgages Payable	MORTGAGES PAYABLE The following table summarizes the Company’s mortgages payable: March 31, 2018 December 31, 2017 Aggregate Principal Balance Weighted Average Interest Rate Weighted Average Years to Maturity Aggregate Principal Balance Weighted Average Interest Rate Weighted Average Years to Maturity Fixed rate mortgages payable (a) $ 275,450 5.00 % 4.8 $ 287,238 4.99 % 5.2 Premium, net of accumulated amortization 962 1,024 Discount, net of accumulated amortization (569 ) (579 ) Capitalized loan fees, net of accumulated amortization (527 ) (615 ) Mortgages payable, net $ 275,316 $ 287,068 (a) The fixed rate mortgages had interest rates ranging from 3.75% to 8.00% as of March 31, 2018 and December 31, 2017 . During the three months ended March 31, 2018 , the Company repaid a $10,750 mortgage payable, which had a fixed interest rate of 4.82% , in conjunction with the disposition of the related property and made scheduled principal payments of $1,038 related to amortizing loans. Debt Maturities The following table shows the scheduled maturities and principal amortization of the Company’s indebtedness as of March 31, 2018 for the remainder of 2018 , each of the next four years and thereafter and the weighted average interest rates by year. The table does not reflect the impact of any debt activity that occurred after March 31, 2018 , such as the Company’s 2018 unsecured credit facility. See Note 8 to the condensed consolidated financial statements for further details regarding the 2018 unsecured credit facility. 2018 2019 2020 2021 2022 Thereafter Total Debt: Fixed rate debt: Mortgages payable (a) $ 3,128 $ 25,257 $ 3,923 $ 22,820 $ 157,216 $ 63,106 $ 275,450 Fixed rate term loans (b) — — — 250,000 — 200,000 450,000 Unsecured notes payable (c) — — — 100,000 — 600,000 700,000 Total fixed rate debt 3,128 25,257 3,923 372,820 157,216 863,106 1,425,450 Variable rate debt: Variable rate term loan and revolving line of credit 100,000 — 91,000 — — — 191,000 Total debt (d) $ 103,128 $ 25,257 $ 94,923 $ 372,820 $ 157,216 $ 863,106 $ 1,616,450 Weighted average interest rate on debt: Fixed rate debt 5.08 % 7.29 % 4.62 % 3.63 % 5.00 % 3.91 % 4.02 % Variable rate debt (e) 3.23 % — 3.23 % — — — 3.23 % Total 3.28 % 7.29 % 3.28 % 3.63 % 5.00 % 3.91 % 3.93 % (a) Excludes mortgage premium of $962 and discount of $(569) , net of accumulated amortization, as of March 31, 2018 . (b) $250,000 of London Interbank Offered Rate (LIBOR)-based variable rate debt has been swapped to a fixed rate through three interest rate swaps. The swaps effectively convert one-month floating rate LIBOR to a fixed rate of 2.00% through January 5, 2021. In addition, $200,000 of LIBOR-based variable rate debt has been swapped to a fixed rate through two interest rate swaps. The swaps effectively convert one-month floating rate LIBOR to a fixed rate of 1.26% through November 22, 2018. (c) Excludes discount of $(823) , net of accumulated amortization, as of March 31, 2018 . (d) The weighted average years to maturity of consolidated indebtedness was 5.1 years as of March 31, 2018 . Total debt excludes capitalized loan fees of $(6,173) , net of accumulated amortization, as of March 31, 2018 , which are included as a reduction to the respective debt balances. (e) Represents interest rates as of March 31, 2018 . The Company plans on addressing its debt maturities through a combination of proceeds from asset dispositions, capital markets transactions and its unsecured revolving line of credit.

Unsecured Notes Payable

Unsecured Notes Payable	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Unsecured Notes Payable	UNSECURED NOTES PAYABLE The following table summarizes the Company’s unsecured notes payable: March 31, 2018 December 31, 2017 Unsecured Notes Payable Maturity Date Principal Balance Interest Rate/ Weighted Average Interest Rate Principal Balance Interest Rate/ Weighted Average Interest Rate Senior notes – 4.12% due 2021 June 30, 2021 $ 100,000 4.12 % $ 100,000 4.12 % Senior notes – 4.58% due 2024 June 30, 2024 150,000 4.58 % 150,000 4.58 % Senior notes – 4.00% due 2025 March 15, 2025 250,000 4.00 % 250,000 4.00 % Senior notes – 4.08% due 2026 September 30, 2026 100,000 4.08 % 100,000 4.08 % Senior notes – 4.24% due 2028 December 28, 2028 100,000 4.24 % 100,000 4.24 % 700,000 4.19 % 700,000 4.19 % Discount, net of accumulated amortization (823 ) (853 ) Capitalized loan fees, net of accumulated amortization (3,275 ) (3,399 ) Total $ 695,902 $ 695,748 Notes Due 2026 and 2028 The note purchase agreement governing the 4.08% senior unsecured notes due 2026 and the 4.24% senior unsecured notes due 2028 (Notes Due 2026 and 2028) contains customary representations, warranties and covenants, and events of default. Pursuant to the terms of the note purchase agreement, the Company is subject to various financial covenants, including the requirement to maintain the following: (i) maximum unencumbered, secured and consolidated leverage ratios; (ii) a minimum interest coverage ratio; (iii) an unencumbered interest coverage ratio (as set forth in the Company’s unsecured credit facility and the note purchase agreement governing the Notes Due 2021 and 2024); and (iv) a fixed charge coverage ratio (as set forth in the Company’s unsecured credit facility). Notes Due 2025 The indenture, as supplemented (the Indenture), governing the 4.00% senior unsecured notes due 2025 (Notes Due 2025) contains customary covenants and events of default. Pursuant to the terms of the Indenture, the Company is subject to various financial covenants, including the requirement to maintain the following: (i) maximum secured and total leverage ratios; (ii) a debt service coverage ratio; and (iii) maintenance of an unencumbered assets to unsecured debt ratio. Notes Due 2021 and 2024 The note purchase agreement governing the 4.12% senior unsecured notes due 2021 and the 4.58% senior unsecured notes due 2024 (Notes Due 2021 and 2024) contains customary representations, warranties and covenants, and events of default. Pursuant to the terms of the note purchase agreement, the Company is subject to various financial covenants, some of which are based upon the financial covenants in effect in the Company’s unsecured credit facility, including the requirement to maintain the following: (i) maximum unencumbered, secured and consolidated leverage ratios; (ii) minimum interest coverage and unencumbered interest coverage ratios; and (iii) a minimum consolidated net worth. As of March 31, 2018 , management believes the Company was in compliance with the financial covenants under the Indenture and the note purchase agreements.

Unsecured Term Loans and Revolv

Unsecured Term Loans and Revolving Line of Credit	3 Months Ended
	Mar. 31, 2018
Line of Credit Facility [Abstract]
Unsecured Term Loans and Revolving Line of Credit	UNSECURED TERM LOANS AND REVOLVING LINE OF CREDIT The following table summarizes the Company’s term loans and revolving line of credit: March 31, 2018 December 31, 2017 Maturity Date Balance Interest Rate Balance Interest Unsecured credit facility term loan due 2021 – fixed rate (a) January 5, 2021 $ 250,000 3.30 % $ 250,000 3.30 % Unsecured credit facility term loan due 2018 – variable rate May 11, 2018 100,000 3.23 % 100,000 2.93 % Unsecured term loan due 2023 – fixed rate (b) November 22, 2023 200,000 2.96 % 200,000 2.96 % Subtotal 550,000 550,000 Capitalized loan fees, net of accumulated amortization (2,371 ) (2,730 ) Term loans, net $ 547,629 $ 547,270 Revolving line of credit – variable rate (c) January 5, 2020 $ 91,000 3.23 % $ 216,000 2.92 % (a) $250,000 of LIBOR -based variable rate debt has been swapped to a fixed rate of 2.00% plus a credit spread based on a leverage grid ranging from 1.30% to 2.20% through January 5, 2021. The applicable credit spread was 1.30% as of March 31, 2018 and December 31, 2017 . (b) $200,000 of LIBOR -based variable rate debt has been swapped to a fixed rate of 1.26% plus a credit spread based on a leverage grid ranging from 1.70% to 2.55% through November 22, 2018. The applicable credit spread was 1.70% as of March 31, 2018 and December 31, 2017 . (c) Excludes capitalized loan fees, which are included in “Other assets, net” in the accompanying condensed consolidated balance sheets. Unsecured Credit Facility On January 6, 2016, the Company entered into its fourth amended and restated unsecured credit agreement (Unsecured Credit Agreement) with a syndicate of financial institutions led by KeyBank National Association serving as administrative agent and Wells Fargo Bank, National Association serving as syndication agent to provide for an unsecured credit facility aggregating $1,200,000 (Unsecured Credit Facility). The Unsecured Credit Facility consists of a $750,000 unsecured revolving line of credit, a $250,000 unsecured term loan and a second unsecured term loan which had an outstanding balance of $200,000 at inception, of which the Company repaid $100,000 during the year ended December 31, 2017, and is priced on a leverage grid at a rate of LIBOR plus a credit spread. The Company received investment grade credit ratings from Moody’s and Standard & Poor’s in 2014. In accordance with the Unsecured Credit Agreement, the Company may elect to convert to an investment grade pricing grid. As of March 31, 2018 , making such an election would have resulted in a higher interest rate and, as such, the Company has not made the election to convert to an investment grade pricing grid. The following table summarizes the key terms of the Unsecured Credit Facility: Leverage-Based Pricing Ratings-Based Pricing Unsecured Credit Facility Maturity Date Extension Option Extension Fee Credit Spread Unused Fee Credit Spread Facility Fee $250,000 unsecured term loan 1/5/2021 N/A N/A 1.30% - 2.20% N/A 0.90% - 1.75% N/A $100,000 unsecured term loan 5/11/2018 2 one year 0.15% 1.45% - 2.20% N/A 1.05% - 2.05% N/A $750,000 unsecured revolving line of credit 1/5/2020 2 six month 0.075% 1.35% - 2.25% 0.15% - 0.25% 0.85% - 1.55% 0.125% - 0.30% The Unsecured Credit Facility has a $400,000 accordion option that allows the Company, at its election, to increase the total credit facility subject to (i) customary fees and conditions including, but not limited to, the absence of an event of default as defined in the Unsecured Credit Agreement and (ii) the Company’s ability to obtain additional lender commitments. The Unsecured Credit Agreement contains customary representations, warranties and covenants, and events of default. Pursuant to the terms of the Unsecured Credit Agreement, the Company is subject to various financial covenants, including the requirement to maintain the following: (i) maximum unencumbered, secured and consolidated leverage ratios; and (ii) minimum fixed charge and unencumbered interest coverage ratios. As of March 31, 2018 , management believes the Company was in compliance with the financial covenants and default provisions under the Unsecured Credit Agreement. Subsequent to March 31, 2018, the Company entered into its fifth amended and restated unsecured credit agreement (2018 Unsecured Credit Agreement) with a syndicate of financial institutions led by Wells Fargo Bank, National Association serving as syndication agent and KeyBank National Association serving as administrative agent to provide for an unsecured credit facility aggregating $1,100,000 (2018 Unsecured Credit Facility). The 2018 Unsecured Credit Facility consists of an $850,000 unsecured revolving line of credit and a $250,000 unsecured term loan and will be priced on a leverage grid at a rate of LIBOR plus a credit spread. In conjunction with the execution of the 2018 Unsecured Credit Agreement, the Company repaid the unsecured term loan due 2018 under the Unsecured Credit Facility that had an outstanding balance of $100,000 as of March 31, 2018. The following table summarizes the key terms of the 2018 Unsecured Credit Facility: Leverage-Based Pricing Ratings-Based Pricing 2018 Unsecured Credit Facility Maturity Date Extension Option Extension Fee Credit Spread Facility Fee Credit Spread Facility Fee $250,000 unsecured term loan 1/5/2021 N/A N/A 1.20% - 1.70% N/A 0.90% - 1.75% N/A $850,000 unsecured revolving line of credit 4/22/2022 2 six month 0.075% 1.05% - 1.50% 0.15% - 0.30% 0.825%-1.55% 0.125% - 0.30% The 2018 Unsecured Credit Facility has a $500,000 accordion option that allows the Company, at its election, to increase the total 2018 Unsecured Credit Facility up to $1,600,000 , subject to (i) customary fees and conditions including, but not limited to, the absence of an event of default as defined in the 2018 Unsecured Credit Agreement and (ii) the Company’s ability to obtain additional lender commitments. The 2018 Unsecured Credit Agreement contains customary representations, warranties and covenants, and events of default. Pursuant to the terms of the 2018 Unsecured Credit Agreement, the Company is subject to various financial covenants, including the requirement to maintain the following: (i) maximum unencumbered, secured and consolidated leverage ratios; and (ii) minimum fixed charge and unencumbered interest coverage ratios. Term Loan Due 2023 On January 3, 2017, the Company received funding on a seven -year $200,000 unsecured term loan with a group of financial institutions, which closed during the year ended December 31, 2016. The Term Loan Due 2023 is priced on a leverage grid at a rate of LIBOR plus a credit spread. In accordance with the term loan agreement (Term Loan Agreement), the Company may elect to convert to an investment grade pricing grid. As of March 31, 2018 , making such an election would have resulted in a higher interest rate and, as such, the Company has not made the election to convert to an investment grade pricing grid. The following table summarizes the key terms of the Term Loan Due 2023: Term Loan Due 2023 Maturity Date Leverage-Based Pricing Credit Spread Ratings-Based Pricing Credit Spread $200,000 unsecured term loan 11/22/2023 1.70% – 2.55% 1.50% – 2.45% The Term Loan Due 2023 has a $100,000 accordion option that allows the Company, at its election, to increase the total unsecured term loan up to $300,000 , subject to customary fees and conditions, including the absence of an event of default as defined in the Term Loan Agreement. The Term Loan Agreement contains customary representations, warranties and covenants, and events of default, including financial covenants that require the Company to maintain the following: (i) maximum unencumbered, secured and consolidated leverage ratios; and (ii) minimum fixed charge and unencumbered interest coverage ratios. As of March 31, 2018 , management believes the Company was in compliance with the financial covenants and default provisions under the Term Loan Agreement.

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	DERIVATIVES The Company elected to early adopt ASU 2017-12, Derivatives and Hedging , as of January 1, 2018. The adoption eliminated the requirement to separately measure and report hedge ineffectiveness. The Company is now required to present the earnings effect of its hedging instruments in the same income statement line item in which it reports the earnings effect of the hedged items. Disclosures related to periods prior to January 1, 2018 are not impacted by the adoption. The Company’s objective in using interest rate derivatives is to manage its exposure to interest rate movements and add stability to interest expense. To accomplish this objective, the Company uses interest rate swaps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable rate amounts from a counterparty in exchange for the Company making fixed rate payments over the life of the agreement without exchange of the underlying notional amount. As of March 31, 2018 , the Company used five interest rate swaps to hedge the variable cash flows associated with variable rate debt. Changes in fair value of the derivatives that are designated and that qualify as cash flow hedges are recorded in “Accumulated other comprehensive income” and are reclassified to interest expense as interest payments are made on the Company’s variable rate debt. Over the next 12 months, the Company estimates that an additional $1,319 will be reclassified as a decrease to interest expense. Prior to January 1, 2018, only the effective portion of changes in fair value of the derivatives that were designated and that qualified as cash flow hedges was recorded in “Accumulated other comprehensive income” and the ineffective portion of the change in fair value of the derivatives was recognized directly in earnings. The following table summarizes the Company’s interest rate swaps as of March 31, 2018 , which effectively convert one-month floating rate LIBOR to a fixed rate: Effective Date Notional Fixed Interest Rate Maturity Date January 3, 2017 $ 100,000 1.26 % November 22, 2018 January 3, 2017 $ 100,000 1.26 % November 22, 2018 December 29, 2017 $ 100,000 2.00 % January 5, 2021 December 29, 2017 $ 100,000 2.00 % January 5, 2021 December 29, 2017 $ 50,000 2.00 % January 5, 2021 The following table summarizes the Company’s interest rate swaps that were designated as cash flow hedges of interest rate risk: Number of Instruments Notional Interest Rate Derivatives March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Interest rate swaps 5 5 $ 450,000 $ 450,000 The table below presents the estimated fair value of the Company’s derivative financial instruments, which are presented within “Other assets, net” in the condensed consolidated balance sheets. The valuation techniques used are described in Note 13 to the condensed consolidated financial statements. Fair Value March 31, 2018 December 31, 2017 Derivatives designated as cash flow hedges: Interest rate swaps $ 3,840 $ 1,086 The following table presents the effect of the Company’s derivative financial instruments on the accompanying condensed consolidated statements of operations and other comprehensive income (loss) for the three months ended March 31, 2018: Derivatives in Cash Flow Hedging Relationships Amount of Gain Recognized in Other Comprehensive Income on Derivative Location of Loss Reclassified from Accumulated Other Comprehensive Income (AOCI) into Income Amount of Loss Reclassified from AOCI into Income Total Interest Expense Presented in the Results of Operations in which the Effects of Cash Flow Hedges are Recorded 2018 2018 2018 Interest rate swaps $ (2,667 ) Interest expense $ 87 $ 18,765 The following table presents the effect of the Company’s derivative financial instruments on the accompanying condensed consolidated statements of operations and other comprehensive income (loss) for the three months ended March 31, 2017: Derivatives in Cash Flow Hedging Relationships Amount of Gain Recognized in Other Comprehensive Income on Derivative (Effective Portion) Location of Loss Reclassified from AOCI into Income (Effective Portion) Amount of Loss Reclassified from AOCI into Income (Effective Portion) Location of Loss Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Amount of Loss Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) 2017 2017 2017 Interest rate swaps $ (472 ) Interest expense $ 160 Other income, net $ 6

Equity

Equity	3 Months Ended
	Mar. 31, 2018
Equity [Abstract]
Equity	EQUITY In December 2015, the Company entered into an at-the-market (ATM) equity program under which it may issue and sell shares of its Class A common stock, having an aggregate offering price of up to $250,000 , from time to time. Actual sales may depend on a variety of factors, including, among others, market conditions and the trading price of the Company’s Class A common stock. Any net proceeds are expected to be used for general corporate purposes, which may include the funding of acquisitions and redevelopment activities and the repayment of debt, including the Company’s unsecured revolving line of credit. The Company did not sell any shares under its ATM equity program during the three months ended March 31, 2018 and 2017 . As of March 31, 2018 , the Company had Class A common shares having an aggregate offering price of up to $250,000 remaining available for sale under its ATM equity program. In December 2015, the Company’s board of directors authorized a common stock repurchase program under which the Company may repurchase, from time to time, up to a maximum of $250,000 of shares of its Class A common stock. In December 2017, The Company’s board of directors authorized a $250,000 increase to the common stock repurchase program. The shares may be repurchased in the open market or in privately negotiated transactions and are canceled upon repurchase. The timing and actual number of shares repurchased will depend on a variety of factors, including price in absolute terms and in relation to the value of the Company’s assets, corporate and regulatory requirements, market conditions and other corporate liquidity requirements and priorities. The common stock repurchase program may be suspended or terminated at any time without prior notice. The Company did not repurchase any shares during the three months ended March 31, 2018 and 2017 . As of March 31, 2018 , $264,057 remained available for repurchases under the common stock repurchase program.

Earnings per Share

Earnings per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings per Share	EARNINGS PER SHARE The following table summarizes the components used in the calculation of basic and diluted earnings per share (EPS): Three Months Ended March 31, 2018 2017 Numerator: Income (loss) from continuing operations $ 7,261 $ (50,264 ) Gain on sales of investment properties 34,519 41,164 Preferred stock dividends — (2,362 ) Net income (loss) attributable to common shareholders 41,780 (11,462 ) Earnings allocated to unvested restricted shares (96 ) (90 ) Net income (loss) attributable to common shareholders excluding amounts attributable to unvested restricted shares $ 41,684 $ (11,552 ) Denominator: Denominator for earnings (loss) per common share – basic: Weighted average number of common shares outstanding 218,849 (a) 236,294 (b) Effect of dilutive securities: Stock options — (c) — (c) RSUs 554 (d) — (e) Denominator for earnings (loss) per common share – diluted: Weighted average number of common and common equivalent shares outstanding 219,403 236,294 (a) Excludes 545 shares of unvested restricted common stock as of March 31, 2018 , which equate to 573 on a weighted average basis for the three months ended March 31, 2018 . These shares will continue to be excluded from the computation of basic EPS until contingencies are resolved and the shares are released. (b) Excludes 534 shares of unvested restricted common stock as of March 31, 2017 , which equate to 565 on a weighted average basis for the three months ended March 31, 2017 . These shares were excluded from the computation of basic EPS as the contingencies remained and the shares had not been released as of the end of the reporting period. (c) There were outstanding options to purchase 38 and 41 shares of common stock as of March 31, 2018 and 2017 , respectively, at a weighted average exercise price of $18.85 and $19.25 , respectively. Of these totals, outstanding options to purchase 38 and 41 shares of common stock as of March 31, 2018 and 2017 , respectively, at a weighted average exercise price of $18.85 and $19.25 , respectively, have been excluded from the common shares used in calculating diluted EPS as including them would be anti-dilutive. (d) As of March 31, 2018 , there were 649 RSUs eligible for future conversion upon completion of the performance periods (see Note 5 to the condensed consolidated financial statements), which equate to 686 RSUs on a weighted average basis for the three months ended March 31, 2018 . These contingently issuable shares are a component of calculating diluted EPS. (e) As of March 31, 2017 , there were 644 RSUs eligible for future conversion upon completion of the performance periods, which equate to 638 RSUs on a weighted average basis for the three months ended March 31, 2017 . These contingently issuable shares are a component of calculating diluted EPS.

Provision for Impairment of Inv

Provision for Impairment of Investment Properties	3 Months Ended
	Mar. 31, 2018
Impairment or Disposal of Tangible Assets Disclosure [Abstract]
Provision for Impairment of Investment Properties	PROVISION FOR IMPAIRMENT OF INVESTMENT PROPERTIES As of March 31, 2018 and 2017 , the Company identified indicators of impairment at certain of its properties. Such indicators included a low occupancy rate, difficulty in leasing space and related cost of re-leasing, financially troubled tenants or reduced anticipated holding periods. The following table summarizes the results of these analyses as of March 31, 2018 and 2017 : March 31, 2018 March 31, 2017 Number of properties for which indicators of impairment were identified 4 (a) 8 (b) Less: number of properties for which an impairment charge was recorded 2 — Less: number of properties that were held for sale as of the date the analysis was performed for which indicators of impairment were identified but no impairment charge was recorded — 4 Remaining properties for which indicators of impairment were identified but no impairment charge was considered necessary 2 4 Weighted average percentage by which the projected undiscounted cash flows exceeded its respective carrying value for each of the remaining properties (c) 39 % 17 % (a) Includes one property which was sold subsequent to March 31, 2018 . (b) Includes five properties which have subsequently been sold as of March 31, 2018 . (c) Based upon the estimated holding period for each asset where an undiscounted cash flow analysis was performed. The Company recorded the following investment property impairment charges during the three months ended March 31, 2018 : Property Name Property Type Impairment Date Square Footage Provision for Impairment of Investment Properties Schaumburg Towers (a) Office March 31, 2018 895,400 $ 392 CVS Pharmacy – Lawton, OK (b) Single-user retail March 31, 2018 10,900 200 $ 592 Estimated fair value of impaired properties as of impairment date $ 70,250 (a) The Company recorded an impairment charge based upon the terms and conditions of an executed sales contract. This property is classified as held for sale as of March 31, 2018 . (b) The Company recorded an impairment charge based upon the terms and conditions of an executed sales contract. The property was sold on April 19, 2018. The Company did not record any investment property impairment charges during the three months ended March 31, 2017 . The Company provides no assurance that material impairment charges with respect to its investment properties will not occur in future periods.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	FAIR VALUE MEASUREMENTS Fair Value of Financial Instruments The following table presents the carrying value and estimated fair value of the Company’s financial instruments: March 31, 2018 December 31, 2017 Carrying Value Fair Value Carrying Value Fair Value Financial assets: Derivative asset $ 3,840 $ 3,840 $ 1,086 $ 1,086 Financial liabilities: Mortgages payable, net $ 275,316 $ 282,063 $ 287,068 $ 298,635 Unsecured notes payable, net $ 695,902 $ 679,372 $ 695,748 $ 693,823 Unsecured term loans, net $ 547,629 $ 552,364 $ 547,270 $ 552,555 Unsecured revolving line of credit $ 91,000 $ 91,247 $ 216,000 $ 216,222 The carrying value of the derivative asset is included in “Other assets, net” in the accompanying condensed consolidated balance sheets. Recurring Fair Value Measurements The following table presents the Company’s financial instruments, which are measured at fair value on a recurring basis, by the level in the fair value hierarchy within which those measurements fall. Methods and assumptions used to estimate the fair value of these instruments are described after the table. Fair Value Level 1 Level 2 Level 3 Total March 31, 2018 Derivative asset $ — $ 3,840 $ — $ 3,840 December 31, 2017 Derivative asset $ — $ 1,086 $ — $ 1,086 Derivative asset: The fair value of the derivative asset is determined using a discounted cash flow analysis on the expected future cash flows of each derivative. This analysis uses observable market data including forward yield curves and implied volatilities to determine the market’s expectation of the future cash flows of the variable component. The fixed and variable components of the derivative are then discounted using calculated discount factors developed based on the LIBOR swap rate and are aggregated to arrive at a single valuation for the period. The Company also incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. Although the Company has determined that the majority of the inputs used to value its derivatives fall within Level 2 of the fair value hierarchy, the credit valuation adjustments associated with its derivatives use Level 3 inputs, such as estimates of current credit spreads to evaluate the likelihood of default by itself and its counterparties. However, as of March 31, 2018 and December 31, 2017 , the Company has assessed the significance of the impact of the credit valuation adjustments on the overall valuation of its derivative positions and has determined that the credit valuation adjustments are not significant to the overall valuation. As a result, the Company has determined that its derivative valuations in their entirety are classified within Level 2 of the fair value hierarchy. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered any applicable credit enhancements. The Company’s derivative instruments are further described in Note 9 to the condensed consolidated financial statements. Nonrecurring Fair Value Measurements The following table presents the Company’s assets measured at fair value on a nonrecurring basis as of March 31, 2018 and December 31, 2017 , aggregated by the level within the fair value hierarchy in which those measurements fall. The table includes information related to properties remeasured to fair value as a result of impairment charges recorded during the three months ended March 31, 2018 and the year ended December 31, 2017 , except for those properties sold prior to March 31, 2018 and December 31, 2017 , respectively. Methods and assumptions used to estimate the fair value of these assets are described after the table. Fair Value Level 1 Level 2 Level 3 Total Provision for Impairment (a) March 31, 2018 Investment property $ — $ 1,600 (b) $ — $ 1,600 $ 200 Investment property – held for sale $ — $ 68,650 (c) $ — $ 68,650 $ 392 December 31, 2017 Investment properties $ — $ 74,250 (d) $ — $ 74,250 $ 50,077 (a) Excludes impairment charges recorded on investment properties sold prior to March 31, 2018 and December 31, 2017 , respectively. (b) Represents the fair value of the Company’s CVS Pharmacy – Lawton, OK investment property as of March 31, 2018, the date the asset was measured at fair value. The estimated fair value of CVS Pharmacy – Lawton, OK was based upon the expected sales price from an executed sales contract and determined to be a Level 2 input. (c) Represents the fair value of the Company’s Schaumburg Towers investment property. The estimated fair value of Schaumburg Towers was based on an expected sales price of $86,600 from an executed sales contract, determined to be a Level 2 input, which contemplates historically deferred maintenance and capital requirements. The estimated fair value of $68,650 as of March 31, 2018, the date the asset was measured at fair value, reflects (i) estimated closing costs and (ii) tenant-related costs expected to be credited to the buyer at close. (d) Represents the fair value of the Company’s Schaumburg Towers and Home Depot Plaza investment properties. The estimated fair value of Schaumburg Towers was based on an expected sales price of $87,600 from a bona fide purchase offer, determined to be a Level 2 input, which contemplates historically deferred maintenance and capital requirements. The estimated fair value of $58,000 as of September 30, 2017, the date the asset was measured at fair value, reflects (i) capital expenditures expected to be incurred by the Company prior to sale and (ii) tenant-related costs expected to be credited to the buyer at close. The estimated fair value of Home Depot Plaza of $16,250 as of December 31, 2017, the date the asset was measured at fair value, was based upon the expected sales price for an executed sales contract and determined to be a Level 2 input. Fair Value Disclosures The following table presents the Company’s financial liabilities, which are measured at fair value for disclosure purposes, by the level in the fair value hierarchy within which those measurements fall. Methods and assumptions used to estimate the fair value of these instruments are described after the table. Fair Value Level 1 Level 2 Level 3 Total March 31, 2018 Mortgages payable, net $ — $ — $ 282,063 $ 282,063 Unsecured notes payable, net $ 236,818 $ — $ 442,554 $ 679,372 Unsecured term loans, net $ — $ — $ 552,364 $ 552,364 Unsecured revolving line of credit $ — $ — $ 91,247 $ 91,247 December 31, 2017 Mortgages payable, net $ — $ — $ 298,635 $ 298,635 Unsecured notes payable, net $ 243,183 $ — $ 450,640 $ 693,823 Unsecured term loans, net $ — $ — $ 552,555 $ 552,555 Unsecured revolving line of credit $ — $ — $ 216,222 $ 216,222 Mortgages payable, net: The Company estimates the fair value of its mortgages payable by discounting the anticipated future cash flows of each instrument at rates currently offered to the Company by its lenders for similar debt instruments of comparable maturities. The rates used are not directly observable in the marketplace and judgment is used in determining the appropriate rate for each of the Company’s individual mortgages payable based upon the specific terms of the agreement, including the term to maturity, the quality and nature of the underlying property and its leverage ratio. The rates used range from 3.7% to 4.4% and 3.5% to 4.2% as of March 31, 2018 and December 31, 2017 , respectively. Unsecured notes payable, net: The quoted market price as of March 31, 2018 was used to value the Notes Due 2025. The Company estimates the fair value of its Notes Due 2021 and 2024 and Notes Due 2026 and 2028 by discounting the future cash flows at rates currently offered to the Company by its lenders for similar debt instruments of comparable maturities. The rates used are not directly observable in the marketplace and judgment is used in determining the appropriate rates. The weighted average rates used were 4.69% and 4.28% as of March 31, 2018 and December 31, 2017 , respectively. Unsecured term loans, net: The Company estimates the fair value of its unsecured term loans, net by discounting the anticipated future cash flows related to the credit spreads at rates currently offered to the Company by its lenders for similar instruments of comparable maturities. The rates used are not directly observable in the marketplace and judgment is used in determining the appropriate rates. The weighted average rate used to discount the credit spreads was 1.33% as of March 31, 2018 and December 31, 2017 . Unsecured revolving line of credit: The Company estimates the fair value of its unsecured revolving line of credit by discounting the anticipated future cash flows related to the credit spreads at rates currently offered to the Company by its lenders for similar facilities of comparable maturity. The rates used are not directly observable in the marketplace and judgment is used in determining the appropriate rates. The rates used to discount the credit spreads were 1.20% and 1.30% as of March 31, 2018 and December 31, 2017 , respectively. There were no transfers between the levels of the fair value hierarchy during the three months ended March 31, 2018 .

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES As of March 31, 2018 , the Company had letters of credit outstanding totaling $9,645 that serve as collateral for certain capital improvements and performance obligations on certain redevelopment projects, which will be satisfied upon completion of the projects, and reduced the available borrowings on its unsecured revolving line of credit. As of March 31, 2018 , the Company had active redevelopments at Reisterstown Road Plaza located in Baltimore, Maryland and Circle East located in Towson, Maryland. The redevelopment portion of Circle East, formerly known as Towson Circle, has been combined with the Company’s neighboring retail operating property formerly known as Towson Square. The Company estimates that it will incur net costs of approximately $9,500 to $10,500 related to the Reisterstown Road Plaza redevelopment and approximately $33,000 to $35,000 related to the Circle East redevelopment. As of March 31, 2018 , the Company has incurred $8,447 related to Reisterstown Road Plaza and $3,409 , which is net of proceeds of $11,820 from the sale of air rights, related to Circle East.

Litigation

Litigation	3 Months Ended
	Mar. 31, 2018
Litigation Disclosure [Abstract]
Legal Matters and Contingencies	LITIGATION The Company is subject, from time to time, to various legal proceedings and claims that arise in the ordinary course of business. While the resolution of such matters cannot be predicted with certainty, management believes, based on currently available information, that the final outcome of such matters will not have a material effect on the Company’s condensed consolidated financial statements.

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2018
Subsequent Events [Abstract]
Subsequent Events	SUBSEQUENT EVENTS Subsequent to March 31, 2018 , the Company: • entered into its fifth amended and restated unsecured credit agreement with a syndicate of financial institutions to provide for an unsecured credit facility aggregating $1,100,000 . In conjunction with the execution of the amended and restated credit agreement, the Company repaid the unsecured term loan due 2018 under the Unsecured Credit Facility that had an outstanding balance of $100,000 as of March 31, 2018. See Note 8 to the condensed consolidated financial statements for further details; • closed on the disposition of CVS Pharmacy – Lawton, OK, a 10,900 square foot single-user retail operating property located in Lawton, Oklahoma, for a sales price of $1,600 with no anticipated gain on sale or additional impairment due to previously recognized impairment charges; and • declared the cash dividend for the second quarter of 2018 of $0.165625 per share on its outstanding Class A common stock, which will be paid on July 10, 2018 to Class A common shareholders of record at the close of business on June 26, 2018.

Summary of Significant Accoun24

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recently Issued Accounting Pronouncements In February 2016, the Financial Accounting Standards Board (FASB) issued ASU 2016-02, Leases . This new guidance is effective January 1, 2019, with early adoption permitted, and will require lessees to recognize a liability to make lease payments and a right-of-use (ROU) asset, initially measured at the present value of lease payments, for both operating and financing leases. For leases with a term of 12 months or less, lessees will be permitted to make an accounting policy election by class of underlying asset to not recognize lease liabilities and lease assets. Upon adoption, the Company will recognize a lease liability and an ROU asset for operating leases where it is the lessee, such as ground leases and office leases. The Company is in the process of evaluating the inputs required to calculate the amounts that will be recorded on its balance sheet for each lease. For leases with a term of 12 months or less, the Company expects to make an accounting policy election by class of underlying asset to not recognize lease liabilities and lease assets. Under this new pronouncement, lessor accounting for lease components will be largely unchanged from existing GAAP. Only incremental direct leasing costs may be capitalized under the new guidance, which is consistent with the Company’s existing policies. The pronouncement allows some optional practical expedients. The Company expects to adopt this new guidance on January 1, 2019 and will continue to evaluate the impact of this guidance until it becomes effective. In June 2016, the FASB issued ASU 2016-13, Financial Instruments – Credit Losses . This new guidance is effective January 1, 2020, with early adoption permitted beginning January 1, 2019, and replaces the current incurred loss impairment methodology with a methodology that reflects expected credit losses. Financial assets that are measured at amortized cost will be required to be presented at the net amount expected to be collected with an allowance for credit losses deducted from the amortized cost basis. In addition, an entity must consider broader information in developing its expected credit loss estimate, including the use of forecasted information. Generally, the pronouncement requires a modified retrospective method of adoption. The Company will continue to evaluate the impact of this guidance until it becomes effective.

Organization and Basis of Pre25

Organization and Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of property ownership	The Company’s property ownership as of March 31, 2018 is summarized below: Wholly-owned (a) Retail operating properties 106 Redevelopment properties 1 (a) Excludes (i) Schaumburg Towers, the Company’s one remaining office complex which is classified as held for sale, (ii) one property where the Company has begun activities in anticipation of future redevelopment and (iii) the redevelopment portion of Circle East, formerly known as Towson Circle, which has been combined with the Company’s neighboring retail operating property formerly known as Towson Square. This combination reduced the Company’s redevelopment property count by one .

Acquisitions (Tables)

Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2018
Business Combinations [Abstract]
Schedule of acquisitions	The Company closed on the following acquisitions during the three months ended March 31, 2017: Date Property Name Metropolitan Property Type Square Footage Acquisition Price January 13, 2017 Main Street Promenade (a) Chicago Multi-tenant retail 181,600 $ 88,000 January 25, 2017 Boulevard at the Capital Centre – Fee Interest Washington, D.C. Fee interest (b) — 2,000 February 24, 2017 One Loudoun Downtown – Phase II Washington, D.C. Additional phase of multi-tenant retail (c) 15,900 4,128 197,500 $ 94,128 (d) (a) This property was acquired through two consolidated VIEs and used to facilitate an Internal Revenue Code Section 1031 tax-deferred exchange (1031 Exchange). (b) The wholly-owned multi-tenant retail operating property located in Largo, Maryland was previously subject to an approximately 70 acre long-term ground lease with a third party. The Company completed a transaction whereby it received the fee interest in approximately 50 acres of the underlying land in exchange for which (i) the Company paid $1,939 and (ii) the term of the ground lease with respect to the remaining approximately 20 acres was shortened to nine months . The Company derecognized building and improvements of $11,347 related to the remaining ground lease, recognized the fair value of land received of $15,200 and recorded a deferred gain of $2,524 as of March 31, 2017, which was recognized during the three months ended December 31, 2017 upon the expiration of the ground lease on approximately 20 acres. The total number of properties in the Company’s portfolio was not affected by this transaction. (c) The Company acquired an additional phase at its One Loudoun Downtown multi-tenant retail operating property, which was accounted for as an asset acquisition. The total number of properties in the Company’s portfolio was not affected by this transaction. (d) Acquisition price does not include capitalized closing costs and adjustments totaling $2,394 .
Schedule of acquisition date fair values	The following table summarizes the acquisition date values, before prorations, the Company recorded in conjunction with the acquisitions discussed above: Three Months Ended March 31, 2017 Land $ 19,926 Building and other improvements, net 75,696 Acquired lease intangible assets (a) 7,343 Acquired lease intangible liabilities (b) (5,367 ) Other liabilities (1,076 ) Net assets acquired $ 96,522 (a) The weighted average amortization period for acquired lease intangible assets is six years for acquisitions completed during the three months ended March 31, 2017. (b) The weighted average amortization period for acquired lease intangible liabilities is 13 years for acquisitions completed during the three months ended March 31, 2017.

Dispositions (Tables)

Dispositions (Tables)	3 Months Ended
	Mar. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Schedule of property dispositions	The Company closed on the following dispositions during the three months ended March 31, 2017: Date Property Name Property Type Square Footage Consideration Aggregate Proceeds, Net (a) Gain January 27, 2017 Rite Aid Store (Eckerd), Culver Rd. – Rochester, NY Single-user retail 10,900 $ 500 $ 332 $ — February 21, 2017 Shoppes at Park West (b) Multi-tenant retail 63,900 15,383 15,261 7,569 March 7, 2017 CVS Pharmacy – Sylacauga, AL (b) Single-user retail 10,100 3,700 3,348 1,651 March 8, 2017 Rite Aid Store (Eckerd) – Kill Devil Hills, NC (b) Single-user retail 13,800 4,297 4,134 1,857 March 15, 2017 Century III Plaza – Home Depot (b) (c) Single-user parcel 131,900 17,519 17,344 4,487 March 16, 2017 Village Shoppes at Gainesville Multi-tenant retail 229,500 41,750 41,380 14,107 March 24, 2017 Northwood Crossing (b) Multi-tenant retail 160,000 22,850 22,723 10,007 620,100 $ 105,999 $ 104,522 $ 39,678 (a) Aggregate proceeds are net of transaction costs. (b) As of March 31, 2017, the following disposition proceeds were temporarily restricted related to 1031 Exchanges and are included in “Other assets, net” in the accompanying condensed consolidated balance sheets: Property Name Proceeds Temporarily Restricted Shoppes at Park West $ 15,272 CVS Pharmacy – Sylacauga, AL 3,332 Rite Aid Store (Eckerd) – Kill Devil Hills, NC 4,114 Century III Plaza – Home Depot 17,031 Northwood Crossing 22,719 $ 62,468 (c) The Company disposed of the Home Depot parcel at Century III Plaza, an existing 284,100 square foot multi-tenant retail operating property. The remaining portion of Century III Plaza was classified as held for sale as of March 31, 2017 and was sold on December 15, 2017. The Company closed on the following dispositions during the three months ended March 31, 2018: Date Property Name Property Type Square Footage Consideration Aggregate Proceeds, Net (a) Gain January 19, 2018 Crown Theater Single-user retail 74,200 $ 6,900 $ 6,350 $ 2,952 February 15, 2018 Cranberry Square Multi-tenant retail 195,200 23,500 23,163 10,174 March 7, 2018 Rite Aid Store (Eckerd)–Crossville, TN Single-user retail 13,800 1,800 1,768 157 March 20, 2018 Home Depot Plaza (b) Multi-tenant retail 135,600 16,250 15,873 — March 21, 2018 Governor's Marketplace Multi-tenant retail 243,100 23,500 20,993 7,429 March 28, 2018 Stony Creek I & Stony Creek II (c) Multi-tenant retail 204,800 32,800 32,078 11,628 866,700 $ 104,750 $ 100,225 $ 32,340 (a) Aggregate proceeds are net of transaction costs and exclude $169 of condemnation proceeds, which did not result in any additional gain recognition. (b) The Company repaid a $10,750 mortgage payable in connection with the disposition of the property. (c) The terms of the disposition of Stony Creek I and Stony Creek II were negotiated as a single transaction.
Schedule of assets and liabilities associated with investment properties held for sale	The following table presents the assets and liabilities associated with the investment properties classified as held for sale: March 31, 2018 December 31, 2017 Assets Land, building and other improvements $ 61,638 $ 2,791 Less accumulated depreciation — (27 ) Net investment properties 61,638 2,764 Other assets 7,161 883 Assets associated with investment properties held for sale $ 68,799 $ 3,647 Liabilities Other liabilities $ 2,673 $ — Liabilities associated with investment properties held for sale $ 2,673 $ —

Equity Compensation Plans (Tabl

Equity Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of unvested restricted shares and restricted stock units	The following table summarizes the Company’s unvested restricted shares as of and for the three months ended March 31, 2018 : Unvested Restricted Shares Weighted Average Grant Date Fair Value per Restricted Share Balance as of January 1, 2018 496 $ 14.81 Shares granted (a) 305 $ 13.02 Shares vested (256 ) $ 15.32 Balance as of March 31, 2018 (b) 545 $ 13.57 (a) Shares granted vest over periods ranging from 0.9 years to three years in accordance with the terms of applicable award agreements. (b) As of March 31, 2018 , total unrecognized compensation expense related to unvested restricted shares was $4,208 , which is expected to be amortized over a weighted average term of 1.6 years . The following table summarizes the Company’s unvested performance restricted stock units (RSUs) as of and for the three months ended March 31, 2018 : Unvested RSUs Weighted Average Grant Date Fair Value per RSU RSUs eligible for future conversion as of January 1, 2018 555 $ 14.60 RSUs granted (a) 291 $ 14.36 Conversion of RSUs to common stock and restricted shares (b) (141 ) $ 14.10 RSUs ineligible for conversion (56 ) $ 15.36 RSUs eligible for future conversion as of March 31, 2018 (c) 649 $ 14.54 (a) Assumptions and inputs as of the grant dates included a weighted average risk-free interest rate of 2.04% , the Company’s historical common stock performance relative to the peer companies within the National Association of Real Estate Investment Trusts (NAREIT) Shopping Center Index and the Company’s weighted average common stock dividend yield of 5.00% . Subject to continued employment, in 2021, following the performance period which concludes on December 31, 2020, one-third of the RSUs that are earned will convert into shares of common stock and two-thirds will convert into restricted shares with a one year vesting term. (b) On February 5, 2018, 141 RSUs converted into 42 shares of common stock and 65 restricted shares that will vest on December 31, 2018, subject to continued employment through such date, after applying a conversion rate of 76% based upon the Company’s Total Shareholder Return (TSR) relative to the TSRs of its peer companies, for the performance period that concluded on December 31, 2017. An additional 16 shares of common stock were also issued representing the dividends that would have been paid on the earned awards during the performance period. (c) As of March 31, 2018 , total unrecognized compensation expense related to unvested RSUs was $6,294 , which is expected to be amortized over a weighted average term of 2.9 years .

Mortgages Payable (Tables)

Mortgages Payable (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Summary of mortgages payable	The following table summarizes the Company’s mortgages payable: March 31, 2018 December 31, 2017 Aggregate Principal Balance Weighted Average Interest Rate Weighted Average Years to Maturity Aggregate Principal Balance Weighted Average Interest Rate Weighted Average Years to Maturity Fixed rate mortgages payable (a) $ 275,450 5.00 % 4.8 $ 287,238 4.99 % 5.2 Premium, net of accumulated amortization 962 1,024 Discount, net of accumulated amortization (569 ) (579 ) Capitalized loan fees, net of accumulated amortization (527 ) (615 ) Mortgages payable, net $ 275,316 $ 287,068 (a) The fixed rate mortgages had interest rates ranging from 3.75% to 8.00% as of March 31, 2018 and December 31, 2017 . The following table summarizes the key terms of the Term Loan Due 2023: Term Loan Due 2023 Maturity Date Leverage-Based Pricing Credit Spread Ratings-Based Pricing Credit Spread $200,000 unsecured term loan 11/22/2023 1.70% – 2.55% 1.50% – 2.45%
Summary of scheduled maturities and principal amortization of indebtedness	The following table shows the scheduled maturities and principal amortization of the Company’s indebtedness as of March 31, 2018 for the remainder of 2018 , each of the next four years and thereafter and the weighted average interest rates by year. The table does not reflect the impact of any debt activity that occurred after March 31, 2018 , such as the Company’s 2018 unsecured credit facility. See Note 8 to the condensed consolidated financial statements for further details regarding the 2018 unsecured credit facility. 2018 2019 2020 2021 2022 Thereafter Total Debt: Fixed rate debt: Mortgages payable (a) $ 3,128 $ 25,257 $ 3,923 $ 22,820 $ 157,216 $ 63,106 $ 275,450 Fixed rate term loans (b) — — — 250,000 — 200,000 450,000 Unsecured notes payable (c) — — — 100,000 — 600,000 700,000 Total fixed rate debt 3,128 25,257 3,923 372,820 157,216 863,106 1,425,450 Variable rate debt: Variable rate term loan and revolving line of credit 100,000 — 91,000 — — — 191,000 Total debt (d) $ 103,128 $ 25,257 $ 94,923 $ 372,820 $ 157,216 $ 863,106 $ 1,616,450 Weighted average interest rate on debt: Fixed rate debt 5.08 % 7.29 % 4.62 % 3.63 % 5.00 % 3.91 % 4.02 % Variable rate debt (e) 3.23 % — 3.23 % — — — 3.23 % Total 3.28 % 7.29 % 3.28 % 3.63 % 5.00 % 3.91 % 3.93 % (a) Excludes mortgage premium of $962 and discount of $(569) , net of accumulated amortization, as of March 31, 2018 . (b) $250,000 of London Interbank Offered Rate (LIBOR)-based variable rate debt has been swapped to a fixed rate through three interest rate swaps. The swaps effectively convert one-month floating rate LIBOR to a fixed rate of 2.00% through January 5, 2021. In addition, $200,000 of LIBOR-based variable rate debt has been swapped to a fixed rate through two interest rate swaps. The swaps effectively convert one-month floating rate LIBOR to a fixed rate of 1.26% through November 22, 2018. (c) Excludes discount of $(823) , net of accumulated amortization, as of March 31, 2018 . (d) The weighted average years to maturity of consolidated indebtedness was 5.1 years as of March 31, 2018 . Total debt excludes capitalized loan fees of $(6,173) , net of accumulated amortization, as of March 31, 2018 , which are included as a reduction to the respective debt balances. (e) Represents interest rates as of March 31, 2018 .

Unsecured Notes Payable (Tables

Unsecured Notes Payable (Tables)	3 Months Ended
	Mar. 31, 2018
Debt Disclosure [Abstract]
Summary of unsecured notes payable	The following table summarizes the Company’s unsecured notes payable: March 31, 2018 December 31, 2017 Unsecured Notes Payable Maturity Date Principal Balance Interest Rate/ Weighted Average Interest Rate Principal Balance Interest Rate/ Weighted Average Interest Rate Senior notes – 4.12% due 2021 June 30, 2021 $ 100,000 4.12 % $ 100,000 4.12 % Senior notes – 4.58% due 2024 June 30, 2024 150,000 4.58 % 150,000 4.58 % Senior notes – 4.00% due 2025 March 15, 2025 250,000 4.00 % 250,000 4.00 % Senior notes – 4.08% due 2026 September 30, 2026 100,000 4.08 % 100,000 4.08 % Senior notes – 4.24% due 2028 December 28, 2028 100,000 4.24 % 100,000 4.24 % 700,000 4.19 % 700,000 4.19 % Discount, net of accumulated amortization (823 ) (853 ) Capitalized loan fees, net of accumulated amortization (3,275 ) (3,399 ) Total $ 695,902 $ 695,748 The following table summarizes the Company’s term loans and revolving line of credit: March 31, 2018 December 31, 2017 Maturity Date Balance Interest Rate Balance Interest Unsecured credit facility term loan due 2021 – fixed rate (a) January 5, 2021 $ 250,000 3.30 % $ 250,000 3.30 % Unsecured credit facility term loan due 2018 – variable rate May 11, 2018 100,000 3.23 % 100,000 2.93 % Unsecured term loan due 2023 – fixed rate (b) November 22, 2023 200,000 2.96 % 200,000 2.96 % Subtotal 550,000 550,000 Capitalized loan fees, net of accumulated amortization (2,371 ) (2,730 ) Term loans, net $ 547,629 $ 547,270 Revolving line of credit – variable rate (c) January 5, 2020 $ 91,000 3.23 % $ 216,000 2.92 % (a) $250,000 of LIBOR -based variable rate debt has been swapped to a fixed rate of 2.00% plus a credit spread based on a leverage grid ranging from 1.30% to 2.20% through January 5, 2021. The applicable credit spread was 1.30% as of March 31, 2018 and December 31, 2017 . (b) $200,000 of LIBOR -based variable rate debt has been swapped to a fixed rate of 1.26% plus a credit spread based on a leverage grid ranging from 1.70% to 2.55% through November 22, 2018. The applicable credit spread was 1.70% as of March 31, 2018 and December 31, 2017 . (c) Excludes capitalized loan fees, which are included in “Other assets, net” in the accompanying condensed consolidated balance sheets.

Unsecured Term Loans and Revo31

Unsecured Term Loans and Revolving Line of Credit (Tables)	3 Months Ended
	Mar. 31, 2018
Line of Credit Facility [Abstract]
Summary of term loans and revolving line of credit	The following table summarizes the Company’s unsecured notes payable: March 31, 2018 December 31, 2017 Unsecured Notes Payable Maturity Date Principal Balance Interest Rate/ Weighted Average Interest Rate Principal Balance Interest Rate/ Weighted Average Interest Rate Senior notes – 4.12% due 2021 June 30, 2021 $ 100,000 4.12 % $ 100,000 4.12 % Senior notes – 4.58% due 2024 June 30, 2024 150,000 4.58 % 150,000 4.58 % Senior notes – 4.00% due 2025 March 15, 2025 250,000 4.00 % 250,000 4.00 % Senior notes – 4.08% due 2026 September 30, 2026 100,000 4.08 % 100,000 4.08 % Senior notes – 4.24% due 2028 December 28, 2028 100,000 4.24 % 100,000 4.24 % 700,000 4.19 % 700,000 4.19 % Discount, net of accumulated amortization (823 ) (853 ) Capitalized loan fees, net of accumulated amortization (3,275 ) (3,399 ) Total $ 695,902 $ 695,748 The following table summarizes the Company’s term loans and revolving line of credit: March 31, 2018 December 31, 2017 Maturity Date Balance Interest Rate Balance Interest Unsecured credit facility term loan due 2021 – fixed rate (a) January 5, 2021 $ 250,000 3.30 % $ 250,000 3.30 % Unsecured credit facility term loan due 2018 – variable rate May 11, 2018 100,000 3.23 % 100,000 2.93 % Unsecured term loan due 2023 – fixed rate (b) November 22, 2023 200,000 2.96 % 200,000 2.96 % Subtotal 550,000 550,000 Capitalized loan fees, net of accumulated amortization (2,371 ) (2,730 ) Term loans, net $ 547,629 $ 547,270 Revolving line of credit – variable rate (c) January 5, 2020 $ 91,000 3.23 % $ 216,000 2.92 % (a) $250,000 of LIBOR -based variable rate debt has been swapped to a fixed rate of 2.00% plus a credit spread based on a leverage grid ranging from 1.30% to 2.20% through January 5, 2021. The applicable credit spread was 1.30% as of March 31, 2018 and December 31, 2017 . (b) $200,000 of LIBOR -based variable rate debt has been swapped to a fixed rate of 1.26% plus a credit spread based on a leverage grid ranging from 1.70% to 2.55% through November 22, 2018. The applicable credit spread was 1.70% as of March 31, 2018 and December 31, 2017 . (c) Excludes capitalized loan fees, which are included in “Other assets, net” in the accompanying condensed consolidated balance sheets.
Summary of unsecured credit facility	The following table summarizes the key terms of the 2018 Unsecured Credit Facility: Leverage-Based Pricing Ratings-Based Pricing 2018 Unsecured Credit Facility Maturity Date Extension Option Extension Fee Credit Spread Facility Fee Credit Spread Facility Fee $250,000 unsecured term loan 1/5/2021 N/A N/A 1.20% - 1.70% N/A 0.90% - 1.75% N/A $850,000 unsecured revolving line of credit 4/22/2022 2 six month 0.075% 1.05% - 1.50% 0.15% - 0.30% 0.825%-1.55% 0.125% - 0.30% The following table summarizes the key terms of the Unsecured Credit Facility: Leverage-Based Pricing Ratings-Based Pricing Unsecured Credit Facility Maturity Date Extension Option Extension Fee Credit Spread Unused Fee Credit Spread Facility Fee $250,000 unsecured term loan 1/5/2021 N/A N/A 1.30% - 2.20% N/A 0.90% - 1.75% N/A $100,000 unsecured term loan 5/11/2018 2 one year 0.15% 1.45% - 2.20% N/A 1.05% - 2.05% N/A $750,000 unsecured revolving line of credit 1/5/2020 2 six month 0.075% 1.35% - 2.25% 0.15% - 0.25% 0.85% - 1.55% 0.125% - 0.30%
Summary of Term Loan Due 2023	The following table summarizes the Company’s mortgages payable: March 31, 2018 December 31, 2017 Aggregate Principal Balance Weighted Average Interest Rate Weighted Average Years to Maturity Aggregate Principal Balance Weighted Average Interest Rate Weighted Average Years to Maturity Fixed rate mortgages payable (a) $ 275,450 5.00 % 4.8 $ 287,238 4.99 % 5.2 Premium, net of accumulated amortization 962 1,024 Discount, net of accumulated amortization (569 ) (579 ) Capitalized loan fees, net of accumulated amortization (527 ) (615 ) Mortgages payable, net $ 275,316 $ 287,068 (a) The fixed rate mortgages had interest rates ranging from 3.75% to 8.00% as of March 31, 2018 and December 31, 2017 . The following table summarizes the key terms of the Term Loan Due 2023: Term Loan Due 2023 Maturity Date Leverage-Based Pricing Credit Spread Ratings-Based Pricing Credit Spread $200,000 unsecured term loan 11/22/2023 1.70% – 2.55% 1.50% – 2.45%

Derivatives (Tables)

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of derivative instruments	The following table summarizes the Company’s interest rate swaps as of March 31, 2018 , which effectively convert one-month floating rate LIBOR to a fixed rate: Effective Date Notional Fixed Interest Rate Maturity Date January 3, 2017 $ 100,000 1.26 % November 22, 2018 January 3, 2017 $ 100,000 1.26 % November 22, 2018 December 29, 2017 $ 100,000 2.00 % January 5, 2021 December 29, 2017 $ 100,000 2.00 % January 5, 2021 December 29, 2017 $ 50,000 2.00 % January 5, 2021
Schedule of interest rate swaps designated as cash flow hedges	The following table summarizes the Company’s interest rate swaps that were designated as cash flow hedges of interest rate risk: Number of Instruments Notional Interest Rate Derivatives March 31, 2018 December 31, 2017 March 31, 2018 December 31, 2017 Interest rate swaps 5 5 $ 450,000 $ 450,000
Schedule of estimated fair value of derivative instruments	The table below presents the estimated fair value of the Company’s derivative financial instruments, which are presented within “Other assets, net” in the condensed consolidated balance sheets. The valuation techniques used are described in Note 13 to the condensed consolidated financial statements. Fair Value March 31, 2018 December 31, 2017 Derivatives designated as cash flow hedges: Interest rate swaps $ 3,840 $ 1,086
Schedule of effect of derivative instruments on the consolidated statements of operations	The following table presents the effect of the Company’s derivative financial instruments on the accompanying condensed consolidated statements of operations and other comprehensive income (loss) for the three months ended March 31, 2018: Derivatives in Cash Flow Hedging Relationships Amount of Gain Recognized in Other Comprehensive Income on Derivative Location of Loss Reclassified from Accumulated Other Comprehensive Income (AOCI) into Income Amount of Loss Reclassified from AOCI into Income Total Interest Expense Presented in the Results of Operations in which the Effects of Cash Flow Hedges are Recorded 2018 2018 2018 Interest rate swaps $ (2,667 ) Interest expense $ 87 $ 18,765 The following table presents the effect of the Company’s derivative financial instruments on the accompanying condensed consolidated statements of operations and other comprehensive income (loss) for the three months ended March 31, 2017: Derivatives in Cash Flow Hedging Relationships Amount of Gain Recognized in Other Comprehensive Income on Derivative (Effective Portion) Location of Loss Reclassified from AOCI into Income (Effective Portion) Amount of Loss Reclassified from AOCI into Income (Effective Portion) Location of Loss Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) Amount of Loss Recognized in Income on Derivative (Ineffective Portion and Amount Excluded from Effectiveness Testing) 2017 2017 2017 Interest rate swaps $ (472 ) Interest expense $ 160 Other income, net $ 6

Earnings per Share (Tables)

Earnings per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Schedule of components used in the calculation of basic and diluted EPS	The following table summarizes the components used in the calculation of basic and diluted earnings per share (EPS): Three Months Ended March 31, 2018 2017 Numerator: Income (loss) from continuing operations $ 7,261 $ (50,264 ) Gain on sales of investment properties 34,519 41,164 Preferred stock dividends — (2,362 ) Net income (loss) attributable to common shareholders 41,780 (11,462 ) Earnings allocated to unvested restricted shares (96 ) (90 ) Net income (loss) attributable to common shareholders excluding amounts attributable to unvested restricted shares $ 41,684 $ (11,552 ) Denominator: Denominator for earnings (loss) per common share – basic: Weighted average number of common shares outstanding 218,849 (a) 236,294 (b) Effect of dilutive securities: Stock options — (c) — (c) RSUs 554 (d) — (e) Denominator for earnings (loss) per common share – diluted: Weighted average number of common and common equivalent shares outstanding 219,403 236,294 (a) Excludes 545 shares of unvested restricted common stock as of March 31, 2018 , which equate to 573 on a weighted average basis for the three months ended March 31, 2018 . These shares will continue to be excluded from the computation of basic EPS until contingencies are resolved and the shares are released. (b) Excludes 534 shares of unvested restricted common stock as of March 31, 2017 , which equate to 565 on a weighted average basis for the three months ended March 31, 2017 . These shares were excluded from the computation of basic EPS as the contingencies remained and the shares had not been released as of the end of the reporting period. (c) There were outstanding options to purchase 38 and 41 shares of common stock as of March 31, 2018 and 2017 , respectively, at a weighted average exercise price of $18.85 and $19.25 , respectively. Of these totals, outstanding options to purchase 38 and 41 shares of common stock as of March 31, 2018 and 2017 , respectively, at a weighted average exercise price of $18.85 and $19.25 , respectively, have been excluded from the common shares used in calculating diluted EPS as including them would be anti-dilutive. (d) As of March 31, 2018 , there were 649 RSUs eligible for future conversion upon completion of the performance periods (see Note 5 to the condensed consolidated financial statements), which equate to 686 RSUs on a weighted average basis for the three months ended March 31, 2018 . These contingently issuable shares are a component of calculating diluted EPS. (e) As of March 31, 2017 , there were 644 RSUs eligible for future conversion upon completion of the performance periods, which equate to 638 RSUs on a weighted average basis for the three months ended March 31, 2017 . These contingently issuable shares are a component of calculating diluted EPS.

Provision for Impairment of I34

Provision for Impairment of Investment Properties (Tables)	3 Months Ended
	Mar. 31, 2018
Impairment or Disposal of Tangible Assets Disclosure [Abstract]
Schedule of identified impairment indicators	As of March 31, 2018 and 2017 , the Company identified indicators of impairment at certain of its properties. Such indicators included a low occupancy rate, difficulty in leasing space and related cost of re-leasing, financially troubled tenants or reduced anticipated holding periods. The following table summarizes the results of these analyses as of March 31, 2018 and 2017 : March 31, 2018 March 31, 2017 Number of properties for which indicators of impairment were identified 4 (a) 8 (b) Less: number of properties for which an impairment charge was recorded 2 — Less: number of properties that were held for sale as of the date the analysis was performed for which indicators of impairment were identified but no impairment charge was recorded — 4 Remaining properties for which indicators of impairment were identified but no impairment charge was considered necessary 2 4 Weighted average percentage by which the projected undiscounted cash flows exceeded its respective carrying value for each of the remaining properties (c) 39 % 17 % (a) Includes one property which was sold subsequent to March 31, 2018 . (b) Includes five properties which have subsequently been sold as of March 31, 2018 . (c) Based upon the estimated holding period for each asset where an undiscounted cash flow analysis was performed.
Schedule of investment property impairment charges	The Company recorded the following investment property impairment charges during the three months ended March 31, 2018 : Property Name Property Type Impairment Date Square Footage Provision for Impairment of Investment Properties Schaumburg Towers (a) Office March 31, 2018 895,400 $ 392 CVS Pharmacy – Lawton, OK (b) Single-user retail March 31, 2018 10,900 200 $ 592 Estimated fair value of impaired properties as of impairment date $ 70,250 (a) The Company recorded an impairment charge based upon the terms and conditions of an executed sales contract. This property is classified as held for sale as of March 31, 2018 . (b) The Company recorded an impairment charge based upon the terms and conditions of an executed sales contract. The property was sold on April 19, 2018.

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Schedule of carrying value and estimated fair value of financial instruments	The following table presents the carrying value and estimated fair value of the Company’s financial instruments: March 31, 2018 December 31, 2017 Carrying Value Fair Value Carrying Value Fair Value Financial assets: Derivative asset $ 3,840 $ 3,840 $ 1,086 $ 1,086 Financial liabilities: Mortgages payable, net $ 275,316 $ 282,063 $ 287,068 $ 298,635 Unsecured notes payable, net $ 695,902 $ 679,372 $ 695,748 $ 693,823 Unsecured term loans, net $ 547,629 $ 552,364 $ 547,270 $ 552,555 Unsecured revolving line of credit $ 91,000 $ 91,247 $ 216,000 $ 216,222
Schedule of financial instruments measured at fair value on a recurring basis	The following table presents the Company’s financial instruments, which are measured at fair value on a recurring basis, by the level in the fair value hierarchy within which those measurements fall. Methods and assumptions used to estimate the fair value of these instruments are described after the table. Fair Value Level 1 Level 2 Level 3 Total March 31, 2018 Derivative asset $ — $ 3,840 $ — $ 3,840 December 31, 2017 Derivative asset $ — $ 1,086 $ — $ 1,086
Schedule of assets measured at fair value on a nonrecurring basis	The following table presents the Company’s assets measured at fair value on a nonrecurring basis as of March 31, 2018 and December 31, 2017 , aggregated by the level within the fair value hierarchy in which those measurements fall. The table includes information related to properties remeasured to fair value as a result of impairment charges recorded during the three months ended March 31, 2018 and the year ended December 31, 2017 , except for those properties sold prior to March 31, 2018 and December 31, 2017 , respectively. Methods and assumptions used to estimate the fair value of these assets are described after the table. Fair Value Level 1 Level 2 Level 3 Total Provision for Impairment (a) March 31, 2018 Investment property $ — $ 1,600 (b) $ — $ 1,600 $ 200 Investment property – held for sale $ — $ 68,650 (c) $ — $ 68,650 $ 392 December 31, 2017 Investment properties $ — $ 74,250 (d) $ — $ 74,250 $ 50,077 (a) Excludes impairment charges recorded on investment properties sold prior to March 31, 2018 and December 31, 2017 , respectively. (b) Represents the fair value of the Company’s CVS Pharmacy – Lawton, OK investment property as of March 31, 2018, the date the asset was measured at fair value. The estimated fair value of CVS Pharmacy – Lawton, OK was based upon the expected sales price from an executed sales contract and determined to be a Level 2 input. (c) Represents the fair value of the Company’s Schaumburg Towers investment property. The estimated fair value of Schaumburg Towers was based on an expected sales price of $86,600 from an executed sales contract, determined to be a Level 2 input, which contemplates historically deferred maintenance and capital requirements. The estimated fair value of $68,650 as of March 31, 2018, the date the asset was measured at fair value, reflects (i) estimated closing costs and (ii) tenant-related costs expected to be credited to the buyer at close. (d) Represents the fair value of the Company’s Schaumburg Towers and Home Depot Plaza investment properties. The estimated fair value of Schaumburg Towers was based on an expected sales price of $87,600 from a bona fide purchase offer, determined to be a Level 2 input, which contemplates historically deferred maintenance and capital requirements. The estimated fair value of $58,000 as of September 30, 2017, the date the asset was measured at fair value, reflects (i) capital expenditures expected to be incurred by the Company prior to sale and (ii) tenant-related costs expected to be credited to the buyer at close. The estimated fair value of Home Depot Plaza of $16,250 as of December 31, 2017, the date the asset was measured at fair value, was based upon the expected sales price for an executed sales contract and determined to be a Level 2 input.
Schedule of financial liabilities measured at fair value for disclosure purposes	The following table presents the Company’s financial liabilities, which are measured at fair value for disclosure purposes, by the level in the fair value hierarchy within which those measurements fall. Methods and assumptions used to estimate the fair value of these instruments are described after the table. Fair Value Level 1 Level 2 Level 3 Total March 31, 2018 Mortgages payable, net $ — $ — $ 282,063 $ 282,063 Unsecured notes payable, net $ 236,818 $ — $ 442,554 $ 679,372 Unsecured term loans, net $ — $ — $ 552,364 $ 552,364 Unsecured revolving line of credit $ — $ — $ 91,247 $ 91,247 December 31, 2017 Mortgages payable, net $ — $ — $ 298,635 $ 298,635 Unsecured notes payable, net $ 243,183 $ — $ 450,640 $ 693,823 Unsecured term loans, net $ — $ — $ 552,555 $ 552,555 Unsecured revolving line of credit $ — $ — $ 216,222 $ 216,222

Organization and Basis of Pre36

Organization and Basis of Presentation (Details)	Mar. 31, 2018propertysubsidiary
Real Estate Properties [Line Items]
Number of wholly-owned subsidiaries jointly elected to be treated as a TRS | subsidiary	1
Wholly-owned | Operating properties
Real Estate Properties [Line Items]
Number of real estate properties owned	106
Wholly-owned | Redevelopment properties
Real Estate Properties [Line Items]
Number of real estate properties owned	1
Decrease in redevelopment property count	1
Wholly-owned | Future redevelopment property
Real Estate Properties [Line Items]
Number of real estate properties owned	1
Investment properties held for sale | Wholly-owned
Real Estate Properties [Line Items]
Number of real estate properties owned	1

Summary of Significant Accoun37

Summary of Significant Accounting Policies Summary of Significant Accounting Policies (Details) $ in Thousands	Jan. 01, 2018USD ($)
Accounting Policies [Abstract]
Cumulative effect of accounting change	$ 12

Acquisitions - Summary of Acqui

Acquisitions - Summary of Acquisitions (Details) $ in Thousands	Feb. 24, 2017USD ($)ft²	Jan. 25, 2017USD ($)aft²	Jan. 13, 2017USD ($)ft²VIE	Mar. 31, 2017USD ($)ft²
Main Street Promenade
Business Acquisition [Line Items]
Square footage | ft²			181,600
Purchase price of asset acquisition			$ 88,000
Boulevard at the Capital Centre
Business Acquisition [Line Items]
Square footage | ft²		0
Purchase price of asset acquisition		$ 2,000
Land subject to ground lease | a		70
Fee interest in land acquired | a		50
Consideration paid for fee interest in land		$ 1,939
Remaining land subject to ground lease | a		20
Term of ground lease		9 months
Amount of building and improvements derecognized		$ 11,347
Fair value of land received		$ 15,200
Deferred gain				$ 2,524
One Loudoun Downtown - Phase II
Business Acquisition [Line Items]
Square footage | ft²	15,900
Purchase price of asset acquisition	$ 4,128
2017 acquisitions
Business Acquisition [Line Items]
Square footage | ft²				197,500
Purchase price of asset acquisition				$ 94,128
Capitalized closing costs and adjustments				$ 2,394
VIE | Main Street Promenade
Business Acquisition [Line Items]
Number of variable interest entities | VIE			2

Acquisitions - Acquisition Date

Acquisitions - Acquisition Date Fair Values (Details) - 2017 acquisitions $ in Thousands	3 Months Ended
	Mar. 31, 2017USD ($)
Acquisition Date Fair Values
Land	$ 19,926
Building and other improvements, net	75,696
Acquired lease intangible assets	7,343
Acquired lease intangible liabilities	(5,367)
Other liabilities	(1,076)
Net assets acquired	$ 96,522
Weighted average amortization period, acquired lease intangible assets	6 years
Weighted average amortization period, acquired lease intangible liabilities	13 years

Acquisitions - Variable Interes

Acquisitions - Variable Interest Entities (Details) - VIE $ in Thousands	Mar. 31, 2017days	Jan. 13, 2017USD ($)
Variable Interest Entity [Line Items]
Number of days to complete tax-deferred exchange | days	180
Main Street Promenade
Variable Interest Entity [Line Items]
Amount loaned to VIE for acquisition | $		$ 87,452

Dispositions - Summary of Dispo

Dispositions - Summary of Dispositions (Details) $ in Thousands

Mar. 28, 2018USD ($)ft²

Mar. 21, 2018USD ($)ft²

Mar. 20, 2018USD ($)ft²

Mar. 07, 2018USD ($)ft²

Feb. 15, 2018USD ($)ft²

Jan. 19, 2018USD ($)ft²

Mar. 31, 2017USD ($)ft²

Mar. 24, 2017USD ($)ft²

Mar. 16, 2017USD ($)ft²

Mar. 15, 2017USD ($)ft²

Mar. 08, 2017USD ($)ft²

Mar. 07, 2017USD ($)ft²

Feb. 21, 2017USD ($)ft²

Jan. 27, 2017USD ($)ft²

Mar. 31, 2018USD ($)ft²

Mar. 31, 2017USD ($)ft²

May 02, 2018USD ($)ft²

Property Dispositions [Line Items]

Aggregate proceeds, net

$ 112,214

$ 104,527

Gain

$ 34,519

$ 41,164

Proceeds temporarily restricted related to 1031 Exchanges

$ 62,468

Crown Theater

Property Dispositions [Line Items]

Square footage | ft²

74,200

Consideration

$ 6,900

Aggregate proceeds, net

6,350

Gain

$ 2,952

Cranberry Square

Property Dispositions [Line Items]

Square footage | ft²

195,200

Consideration

$ 23,500

Aggregate proceeds, net

23,163

Gain

$ 10,174

Rite Aid Store (Eckerd) - Crossville, TN

Property Dispositions [Line Items]

Square footage | ft²

13,800

Consideration

$ 1,800

Aggregate proceeds, net

1,768

Gain

$ 157

Home Depot Plaza

Property Dispositions [Line Items]

Square footage | ft²

135,600

Consideration

$ 16,250

Aggregate proceeds, net

15,873

Gain

0

Mortgage payable repaid

$ 10,750

Governor's Marketplace

Property Dispositions [Line Items]

Square footage | ft²

243,100

Consideration

$ 23,500

Aggregate proceeds, net

20,993

Gain

$ 7,429

Stony Creek I & Stony Creek II

Property Dispositions [Line Items]

Square footage | ft²

204,800

Consideration

$ 32,800

Aggregate proceeds, net

32,078

Gain

$ 11,628

2018 dispositions

Property Dispositions [Line Items]

Square footage | ft²

866,700

Consideration

$ 104,750

Aggregate proceeds, net

100,225

Gain

32,340

Condemnation proceeds

169

Circle East

Property Dispositions [Line Items]

Aggregate proceeds, net

11,820

Gain

$ 2,179

Rite Aid Store (Eckerd), Culver Rd., Rochester, NY

Property Dispositions [Line Items]

Square footage | ft²

10,900

Consideration

$ 500

Aggregate proceeds, net

332

Gain

$ 0

Shoppes at Park West

Property Dispositions [Line Items]

Square footage | ft²

63,900

Consideration

$ 15,383

Aggregate proceeds, net

15,261

Gain

$ 7,569

Proceeds temporarily restricted related to 1031 Exchanges

15,272

CVS Pharmacy - Sylacauga, AL

Property Dispositions [Line Items]

Square footage | ft²

10,100

Consideration

$ 3,700

Aggregate proceeds, net

3,348

Gain

$ 1,651

Proceeds temporarily restricted related to 1031 Exchanges

3,332

Rite Aid Store (Eckerd) - Kill Devil Hills, NC

Property Dispositions [Line Items]

Square footage | ft²

13,800

Consideration

$ 4,297

Aggregate proceeds, net

4,134

Gain

$ 1,857

Proceeds temporarily restricted related to 1031 Exchanges

4,114

Century III Plaza - Home Depot

Property Dispositions [Line Items]

Square footage | ft²

131,900

Consideration

$ 17,519

Aggregate proceeds, net

17,344

Gain

$ 4,487

Proceeds temporarily restricted related to 1031 Exchanges

17,031

Village Shoppes at Gainesville

Property Dispositions [Line Items]

Square footage | ft²

229,500

Consideration

$ 41,750

Aggregate proceeds, net

41,380

Gain

$ 14,107

Northwood Crossing

Property Dispositions [Line Items]

Square footage | ft²

160,000

Consideration

$ 22,850

Aggregate proceeds, net

22,723

Gain

$ 10,007

Proceeds temporarily restricted related to 1031 Exchanges

$ 22,719

2017 dispositions

Property Dispositions [Line Items]

Square footage | ft²

620,100

620,100

Consideration

$ 105,999

$ 105,999

Aggregate proceeds, net

104,522

Gain

39,678

Century III Plaza

Property Dispositions [Line Items]

Square footage | ft²

284,100

Maple Tree Place

Property Dispositions [Line Items]

Aggregate proceeds, net

5

Gain

$ 1,486

Subsequent events | CVS Pharmacy - Lawton, OK

Property Dispositions [Line Items]

Square footage | ft²

10,900

Consideration

$ 1,600

Dispositions - Assets and Liabi

Dispositions - Assets and Liabilities of Investment Properties Held for Sale (Details) $ in Thousands	Mar. 31, 2018USD ($)ft²	Dec. 31, 2017USD ($)
Assets
Assets associated with investment properties held for sale	$ 68,799	$ 3,647
Liabilities
Liabilities associated with investment properties held for sale	2,673	0
Investment properties held for sale
Assets
Land, building and other improvements	61,638	2,791
Less accumulated depreciation	0	(27)
Net investment properties	61,638	2,764
Other assets	7,161	883
Assets associated with investment properties held for sale	68,799	3,647
Liabilities
Other liabilities	2,673	0
Liabilities associated with investment properties held for sale	$ 2,673	$ 0
Investment properties held for sale | Schaumburg Towers
Long Lived Assets Held-for-sale [Line Items]
Square footage | ft²	895,400

Equity Compensation Plans (Deta

Equity Compensation Plans (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	Feb. 05, 2018	Mar. 31, 2018	Mar. 31, 2017
Share-based Compensation Arrangement [Line Items]
Number of options outstanding		38	41
Restricted shares
Share-based Compensation Arrangement [Line Items]
Number of shares in which vesting was accelerated		23
Fair value of restricted shares vested		$ 3,161
Equity Instruments, Nonvested [Roll Forward]
Balance at the beginning of the period (in shares)		496
Shares/RSUs granted (in shares)		305
Shares/RSUs vested (in shares)		(256)
Balance at the end of the period (in shares)		545	534
Equity Instruments, Nonvested, Weighted Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per share)		$ 14.81
Shares/RSUs granted (in dollars per share)		13.02
Shares/RSUs vested (in dollars per share)		15.32
Balance at the end of the period (in dollars per share)		$ 13.57
Compensation Cost Not Yet Recognized
Total unrecognized compensation expense		$ 4,208
Unrecognized compensation expense, period for recognition (in years)		1 year 7 months 10 days
RSUs
Share-based Compensation Arrangement [Line Items]
Vesting period for shares/RSUs granted		1 year
Risk-free interest rate (as a percent)		2.04%
Common stock dividend yield (as a percent)		5.00%
Conversion rate of RSUs into shares of common stock (as a percent)		33.00%
Conversion rate of RSUs into restricted shares (as a percent)		67.00%
Number of shares in which vesting was accelerated		29
Equity Instruments, Nonvested [Roll Forward]
Balance at the beginning of the period (in shares)		555
Shares/RSUs granted (in shares)		291
Shares/RSUs vested (in shares)		(141)
Shares/RSUs forfeited (in shares)		(56)
Balance at the end of the period (in shares)		649
Equity Instruments, Nonvested, Weighted Average Grant Date Fair Value
Balance at the beginning of the period (in dollars per share)		$ 14.60
Shares/RSUs granted (in dollars per share)		14.36
Shares/RSUs vested (in dollars per share)		14.10
Shares/RSUs forfeited (in dollars per share)		15.36
Balance at the end of the period (in dollars per share)		$ 14.54
Compensation Cost Not Yet Recognized
Total unrecognized compensation expense		$ 6,294
Unrecognized compensation expense, period for recognition (in years)		2 years 11 months
Restricted shares and RSUs
Share-based Compensation Arrangement [Line Items]
Compensation expense		$ 2,133	$ 1,793
Additional compensation expense		$ 330
Minimum | Restricted shares
Share-based Compensation Arrangement [Line Items]
Vesting period for shares/RSUs granted		11 months
Maximum | Restricted shares
Share-based Compensation Arrangement [Line Items]
Vesting period for shares/RSUs granted		3 years
2015 RSU grant | Restricted shares
Share-based Compensation Arrangement [Line Items]
Number of shares issued	65
2015 RSU grant | RSUs
Share-based Compensation Arrangement [Line Items]
Number of RSUs converted	141
Conversion rate (as a percent)	76.00%
2015 RSU grant | Class A common stock
Share-based Compensation Arrangement [Line Items]
Number of shares issued	42
2015 RSU grant | Dividends | Class A common stock
Share-based Compensation Arrangement [Line Items]
Number of shares issued	16

Mortgages Payable - Summary (De

Mortgages Payable - Summary (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Fixed rate mortgages payable	$ 1,616,450
Weighted average interest rate (as a percent)	3.93%
Fixed rate debt
Debt Instrument [Line Items]
Fixed rate mortgages payable	$ 1,425,450
Weighted average interest rate (as a percent)	4.02%
Mortgages payable
Debt Instrument [Line Items]
Premium, net of accumulated amortization	$ 962	$ 1,024
Discount, net of accumulated amortization	(569)	(579)
Capitalized loan fees, net of accumulated amortization	(527)	(615)
Mortgages payable, net	275,316	287,068
Amount of mortgages payable repaid	10,750
Scheduled principal payments related to amortizing loans	1,038
Mortgages payable | Fixed rate debt
Debt Instrument [Line Items]
Fixed rate mortgages payable	$ 275,450	$ 287,238
Weighted average interest rate (as a percent)	5.00%	4.99%
Weighted average years to maturity	4 years 10 months	5 years 2 months 15 days
Minimum | Mortgages payable
Debt Instrument [Line Items]
Fixed interest rate (as a percent)	3.75%	3.75%
Maximum | Mortgages payable
Debt Instrument [Line Items]
Fixed interest rate (as a percent)	8.00%	8.00%
Debt repaid or defeased | Mortgages payable
Debt Instrument [Line Items]
Fixed interest rate (as a percent)	4.82%

Mortgages Payable - Debt Maturi

Mortgages Payable - Debt Maturities (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018USD ($)instrument	Dec. 31, 2017USD ($)
Long-term Debt, Fiscal Year Maturity
2,018	$ 103,128
2,019	25,257
2,020	94,923
2,021	372,820
2,022	157,216
Thereafter	863,106
Total	$ 1,616,450
Long-term Debt, Weighted Average Interest Rate
2,018	3.28%
2,019	7.29%
2,020	3.28%
2,021	3.63%
2,022	5.00%
Thereafter	3.91%
Total	3.93%
Mortgages payable
Debt Instrument [Line Items]
Premium, net of accumulated amortization	$ 962	$ 1,024
Discount, net of accumulated amortization	(569)	(579)
Capitalized loan fees, net of accumulated amortization	(527)	(615)
Unsecured notes payable
Debt Instrument [Line Items]
Discount, net of accumulated amortization	(823)	(853)
Capitalized loan fees, net of accumulated amortization	$ (3,275)	$ (3,399)
Consolidated indebtedness
Debt Instrument [Line Items]
Weighted average years to maturity	5 years 1 month 10 days
Capitalized loan fees, net of accumulated amortization	$ (6,173)
Fixed rate debt
Long-term Debt, Fiscal Year Maturity
2,018	3,128
2,019	25,257
2,020	3,923
2,021	372,820
2,022	157,216
Thereafter	863,106
Total	$ 1,425,450
Long-term Debt, Weighted Average Interest Rate
2,018	5.08%
2,019	7.29%
2,020	4.62%
2,021	3.63%
2,022	5.00%
Thereafter	3.91%
Total	4.02%
Fixed rate debt | Mortgages payable
Debt Instrument [Line Items]
Weighted average years to maturity	4 years 10 months	5 years 2 months 15 days
Long-term Debt, Fiscal Year Maturity
2,018	$ 3,128
2,019	25,257
2,020	3,923
2,021	22,820
2,022	157,216
Thereafter	63,106
Total	$ 275,450	$ 287,238
Long-term Debt, Weighted Average Interest Rate
Total	5.00%	4.99%
Fixed rate debt | Unsecured term loans
Long-term Debt, Fiscal Year Maturity
2,018	$ 0
2,019	0
2,020	0
2,021	250,000
2,022	0
Thereafter	200,000
Total	450,000
Fixed rate debt | Unsecured notes payable
Long-term Debt, Fiscal Year Maturity
2,018	0
2,019	0
2,020	0
2,021	100,000
2,022	0
Thereafter	600,000
Total	$ 700,000
Variable rate debt
Long-term Debt, Weighted Average Interest Rate
2,018	3.23%
2,019	0.00%
2,020	3.23%
2,021	0.00%
2,022	0.00%
Thereafter	0.00%
Total	3.23%
Variable rate debt | Variable rate term loan and revolving line of credit
Long-term Debt, Fiscal Year Maturity
2,018	$ 100,000
2,019	0
2,020	91,000
2,021	0
2,022	0
Thereafter	0
Total	191,000
Two $100,00 and one $50,000 interest rate swaps maturing in 2021
Debt Instrument [Line Items]
Variable rate debt swapped to fixed rate	$ 250,000
Number of instruments | instrument	3
Fixed interest rate (as a percent)	2.00%
Two $100,000 interest rate swaps maturing in 2018
Debt Instrument [Line Items]
Variable rate debt swapped to fixed rate	$ 200,000
Number of instruments | instrument	2
Fixed interest rate (as a percent)	1.26%
LIBOR | Two $100,00 and one $50,000 interest rate swaps maturing in 2021
Debt Instrument [Line Items]
Reference rate for variable interest rate	one-month floating rate LIBOR
LIBOR | Two $100,000 interest rate swaps maturing in 2018
Debt Instrument [Line Items]
Reference rate for variable interest rate	one-month floating rate LIBOR

Unsecured Notes Payable (Detail

Unsecured Notes Payable (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Principal balance	$ 695,902	$ 695,748
Senior Notes
Debt Instrument [Line Items]
Principal balance	700,000	700,000
Discount, net of accumulated amortization	(823)	(853)
Capitalized loan fees, net of accumulated amortization	$ (3,275)	$ (3,399)
Weighted average interest rate (as a percent)	4.19%	4.19%
Senior Notes | 4.12% Notes Due 2021
Debt Instrument [Line Items]
Principal balance	$ 100,000	$ 100,000
Stated interest rate (as a percent)	4.12%	4.12%
Senior Notes | 4.58% Notes Due 2024
Debt Instrument [Line Items]
Principal balance	$ 150,000	$ 150,000
Stated interest rate (as a percent)	4.58%	4.58%
Senior Notes | 4.00% Notes Due 2025
Debt Instrument [Line Items]
Principal balance	$ 250,000	$ 250,000
Stated interest rate (as a percent)	4.00%	4.00%
Senior Notes | 4.08% Notes Due 2026
Debt Instrument [Line Items]
Principal balance	$ 100,000	$ 100,000
Stated interest rate (as a percent)	4.08%	4.08%
Senior Notes | 4.24% Notes Due 2028
Debt Instrument [Line Items]
Principal balance	$ 100,000	$ 100,000
Stated interest rate (as a percent)	4.24%	4.24%

Unsecured Credit Facility (Deta

Unsecured Credit Facility (Details) $ in Thousands	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Jan. 03, 2017USD ($)	Jan. 06, 2016USD ($)extension_options	May 02, 2018USD ($)extension_options	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Line of Credit Facility [Line Items]
Unsecured term loans	$ 547,629	$ 547,270				$ 547,629	$ 547,270
Revolving line of credit	$ 91,000	$ 216,000				91,000	216,000
Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)	1.30%	1.30%
Unsecured credit facility term loan due 2018
Line of Credit Facility [Line Items]
Repayment of unsecured term loan							100,000
Unsecured term loans
Line of Credit Facility [Line Items]
Unsecured term loans	$ 550,000	$ 550,000				550,000	550,000
Capitalized loan fees, net of accumulated amortization	(2,371)	(2,730)				(2,371)	(2,730)
Term loans, net	$ 547,629	$ 547,270				547,629	547,270
Term Loan Due 2023
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)	1.70%	1.70%
Principal amount			$ 200,000
Fixed rate debt | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Unsecured term loans	$ 250,000	$ 250,000				$ 250,000	$ 250,000
Interest rate (as a percent)	3.30%	3.30%				3.30%	3.30%
Fixed rate debt | Term Loan Due 2023
Line of Credit Facility [Line Items]
Unsecured term loans	$ 200,000	$ 200,000				$ 200,000	$ 200,000
Interest rate on term loan (as a percent)	2.96%	2.96%
Variable rate debt | Unsecured credit facility term loan due 2018
Line of Credit Facility [Line Items]
Unsecured term loans	$ 100,000	$ 100,000				$ 100,000	$ 100,000
Interest rate (as a percent)	3.23%	2.93%				3.23%	2.93%
Variable rate debt | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Revolving line of credit	$ 91,000	$ 216,000				$ 91,000	$ 216,000
Interest rate (as a percent)	3.23%	2.92%				3.23%	2.92%
Two $100,00 and one $50,000 interest rate swaps maturing in 2021
Line of Credit Facility [Line Items]
Variable rate debt swapped to fixed rate	$ 250,000					$ 250,000
Fixed interest rate (as a percent)	2.00%					2.00%
Two $100,00 and one $50,000 interest rate swaps maturing in 2021 | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable rate debt swapped to fixed rate	$ 250,000					$ 250,000
Fixed interest rate (as a percent)	2.00%					2.00%
Two $100,000 interest rate swaps maturing in 2018
Line of Credit Facility [Line Items]
Variable rate debt swapped to fixed rate	$ 200,000					$ 200,000
Fixed interest rate (as a percent)	1.26%					1.26%
Two $100,000 interest rate swaps maturing in 2018 | Term Loan Due 2023
Line of Credit Facility [Line Items]
Variable rate debt swapped to fixed rate	$ 200,000					$ 200,000
Fixed interest rate (as a percent)	1.26%					1.26%
LIBOR | Unsecured Credit Facility
Line of Credit Facility [Line Items]
Reference rate for variable interest rate				LIBOR
LIBOR | Term Loan Due 2023
Line of Credit Facility [Line Items]
Reference rate for variable interest rate			LIBOR
LIBOR | Two $100,00 and one $50,000 interest rate swaps maturing in 2021
Line of Credit Facility [Line Items]
Reference rate for variable interest rate						one-month floating rate LIBOR
LIBOR | Two $100,00 and one $50,000 interest rate swaps maturing in 2021 | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Reference rate for variable interest rate	LIBOR
LIBOR | Two $100,000 interest rate swaps maturing in 2018
Line of Credit Facility [Line Items]
Reference rate for variable interest rate						one-month floating rate LIBOR
LIBOR | Two $100,000 interest rate swaps maturing in 2018 | Term Loan Due 2023
Line of Credit Facility [Line Items]
Reference rate for variable interest rate	LIBOR
Minimum | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)	1.30%
Minimum | Term Loan Due 2023
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)	1.70%
Minimum | LIBOR | Term Loan Due 2023
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)			1.70%
Maximum | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)	2.20%
Maximum | Term Loan Due 2023
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)	2.55%
Maximum | LIBOR | Term Loan Due 2023
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)			2.55%
KeyBank and Wells Fargo Syndicate | Unsecured Credit Facility
Line of Credit Facility [Line Items]
Aggregate borrowing capacity				$ 1,200,000
Additional borrowing capacity				400,000
KeyBank and Wells Fargo Syndicate | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Principal amount				250,000
KeyBank and Wells Fargo Syndicate | Unsecured credit facility term loan due 2018
Line of Credit Facility [Line Items]
Principal amount				$ 200,000
Number of extension options | extension_options				2
Term loan, period of extension of maturity (in years)				1 year
Term loan, extension fee as a percentage of amount outstanding				0.15%
KeyBank and Wells Fargo Syndicate | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Aggregate borrowing capacity				$ 750,000
Number of extension options | extension_options				2
Revolving line of credit, period of extension of maturity (in years)				6 months
Revolving line of credit, extension fee as a percentage of commitment amount				0.075%
KeyBank and Wells Fargo Syndicate | Minimum | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Quarterly unused fees (as a percent)				0.15%
KeyBank and Wells Fargo Syndicate | Minimum | LIBOR | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				1.30%
KeyBank and Wells Fargo Syndicate | Minimum | LIBOR | Unsecured credit facility term loan due 2018
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				1.45%
KeyBank and Wells Fargo Syndicate | Minimum | LIBOR | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				1.35%
KeyBank and Wells Fargo Syndicate | Maximum | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Quarterly unused fees (as a percent)				0.25%
KeyBank and Wells Fargo Syndicate | Maximum | LIBOR | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				2.20%
KeyBank and Wells Fargo Syndicate | Maximum | LIBOR | Unsecured credit facility term loan due 2018
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				2.20%
KeyBank and Wells Fargo Syndicate | Maximum | LIBOR | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				2.25%
Investment grade rated | Minimum | LIBOR | Term Loan Due 2023
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)			1.50%
Investment grade rated | Maximum | LIBOR | Term Loan Due 2023
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)			2.45%
Investment grade rated | KeyBank and Wells Fargo Syndicate | Minimum | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Facility fee (as a percent)				0.125%
Investment grade rated | KeyBank and Wells Fargo Syndicate | Minimum | LIBOR | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				0.90%
Investment grade rated | KeyBank and Wells Fargo Syndicate | Minimum | LIBOR | Unsecured credit facility term loan due 2018
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				1.05%
Investment grade rated | KeyBank and Wells Fargo Syndicate | Minimum | LIBOR | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				0.85%
Investment grade rated | KeyBank and Wells Fargo Syndicate | Maximum | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Facility fee (as a percent)				0.30%
Investment grade rated | KeyBank and Wells Fargo Syndicate | Maximum | LIBOR | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				1.75%
Investment grade rated | KeyBank and Wells Fargo Syndicate | Maximum | LIBOR | Unsecured credit facility term loan due 2018
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				2.05%
Investment grade rated | KeyBank and Wells Fargo Syndicate | Maximum | LIBOR | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)				1.55%
Subsequent events | Unsecured credit facility term loan due 2018
Line of Credit Facility [Line Items]
Repayment of unsecured term loan					$ 100,000
Subsequent events | KeyBank and Wells Fargo Syndicate | Unsecured credit facility term loan due 2018
Line of Credit Facility [Line Items]
Repayment of unsecured term loan					100,000
Subsequent events | 2018 Wells Fargo and KeyBank Syndicate | Unsecured Credit Facility
Line of Credit Facility [Line Items]
Aggregate borrowing capacity					1,100,000
Additional borrowing capacity					500,000
Maximum borrowing capacity					1,600,000
Subsequent events | 2018 Wells Fargo and KeyBank Syndicate | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Principal amount					250,000
Subsequent events | 2018 Wells Fargo and KeyBank Syndicate | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Aggregate borrowing capacity					$ 850,000
Number of extension options | extension_options					2
Revolving line of credit, period of extension of maturity (in years)					6 months
Revolving line of credit, extension fee as a percentage of commitment amount					0.075%
Subsequent events | 2018 Wells Fargo and KeyBank Syndicate | Minimum | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Facility fee (as a percent)					0.15%
Subsequent events | 2018 Wells Fargo and KeyBank Syndicate | Minimum | LIBOR | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)					1.20%
Subsequent events | 2018 Wells Fargo and KeyBank Syndicate | Minimum | LIBOR | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)					1.05%
Subsequent events | 2018 Wells Fargo and KeyBank Syndicate | Maximum | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Facility fee (as a percent)					0.30%
Subsequent events | 2018 Wells Fargo and KeyBank Syndicate | Maximum | LIBOR | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)					1.70%
Subsequent events | 2018 Wells Fargo and KeyBank Syndicate | Maximum | LIBOR | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)					1.50%
Subsequent events | Investment grade rated | 2018 Wells Fargo and KeyBank Syndicate | Minimum | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Facility fee (as a percent)					0.125%
Subsequent events | Investment grade rated | 2018 Wells Fargo and KeyBank Syndicate | Minimum | LIBOR | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)					0.90%
Subsequent events | Investment grade rated | 2018 Wells Fargo and KeyBank Syndicate | Minimum | LIBOR | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)					0.825%
Subsequent events | Investment grade rated | 2018 Wells Fargo and KeyBank Syndicate | Maximum | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Facility fee (as a percent)					0.30%
Subsequent events | Investment grade rated | 2018 Wells Fargo and KeyBank Syndicate | Maximum | LIBOR | Unsecured credit facility term loan due 2021
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)					1.75%
Subsequent events | Investment grade rated | 2018 Wells Fargo and KeyBank Syndicate | Maximum | LIBOR | Unsecured revolving line of credit
Line of Credit Facility [Line Items]
Variable interest rate spread (as a percent)					1.55%

Term Loan Due 2023 (Details)

Term Loan Due 2023 (Details) - Term Loan Due 2023 - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Jan. 03, 2017
Debt Instrument [Line Items]
Term of debt issuance			7 years
Principal amount			$ 200,000
Variable interest rate spread (as a percent)	1.70%	1.70%
Additional borrowing capacity			100,000
Maximum borrowing capacity			$ 300,000
LIBOR
Debt Instrument [Line Items]
Reference rate for variable interest rate			LIBOR
Minimum
Debt Instrument [Line Items]
Variable interest rate spread (as a percent)	1.70%
Minimum | LIBOR
Debt Instrument [Line Items]
Variable interest rate spread (as a percent)			1.70%
Maximum
Debt Instrument [Line Items]
Variable interest rate spread (as a percent)	2.55%
Maximum | LIBOR
Debt Instrument [Line Items]
Variable interest rate spread (as a percent)			2.55%
Investment grade rated | Minimum | LIBOR
Debt Instrument [Line Items]
Variable interest rate spread (as a percent)			1.50%
Investment grade rated | Maximum | LIBOR
Debt Instrument [Line Items]
Variable interest rate spread (as a percent)			2.45%

Derivatives - Schedule of Deriv

Derivatives - Schedule of Derivative Instruments (Details) - Cash flow hedges $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)instrument	Dec. 31, 2017USD ($)instrument
Interest rate swaps
Derivative [Line Items]
Number of instruments | instrument	5	5
Amount expected to be reclassified to interest expense over the next 12 months	$ 1,319
Notional	450,000	$ 450,000
$100,000 interest rate swap maturing in 2018 no. 1
Derivative [Line Items]
Notional	$ 100,000
Fixed interest rate (as a percent)	1.26%
$100,000 interest rate swap maturing in 2018 no. 2
Derivative [Line Items]
Notional	$ 100,000
Fixed interest rate (as a percent)	1.26%
$100,000 interest rate swap maturing in 2021 no. 1
Derivative [Line Items]
Notional	$ 100,000
Fixed interest rate (as a percent)	2.00%
$100,000 interest rate swap maturing in 2021 no. 2
Derivative [Line Items]
Notional	$ 100,000
Fixed interest rate (as a percent)	2.00%
$50,000 interest rate swap maturing in 2021
Derivative [Line Items]
Notional	$ 50,000
Fixed interest rate (as a percent)	2.00%
LIBOR
Derivative [Line Items]
Reference rate for variable interest rate	one-month floating rate LIBOR

Derivatives - Interest Rate Swa

Derivatives - Interest Rate Swaps Designated as Cash Flow Hedges (Details) - Interest rate swaps - Cash flow hedges $ in Thousands	Mar. 31, 2018USD ($)instrument	Dec. 31, 2017USD ($)instrument
Derivative [Line Items]
Number of instruments | instrument	5	5
Notional | $	$ 450,000	$ 450,000

Derivatives - Estimated Fair Va

Derivatives - Estimated Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Interest rate swaps | Cash flow hedges
Derivatives, Fair Value [Line Items]
Fair value of interest rate swaps	$ 3,840	$ 1,086

Derivatives - Effect on Stateme

Derivatives - Effect on Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, (Gain) Loss [Line Items]
Interest expense presented in the Results of Operations in which the effects of cash flow hedges are recorded	$ 18,765	$ 85,532
Interest rate swaps | Cash flow hedges
Derivative Instruments, (Gain) Loss [Line Items]
Amount of gain recognized in other comprehensive income on derivative (effective portion)	(2,667)	(472)
Amount of loss reclassified from AOCI into income (effective portion)	$ 87	160
Amount of loss recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)		$ 6

Equity (Details)

Equity (Details) - USD ($) $ in Thousands	1 Months Ended
	Dec. 31, 2015	Mar. 31, 2018	Dec. 31, 2017
2015 ATM Equity Program
Class of Stock [Line Items]
Maximum aggregate offering price	$ 250,000
Aggregate offering price of remaining common shares available for sale		$ 250,000
2015 Share Repurchase Program
Class of Stock [Line Items]
Maximum authorized amount for stock repurchases	$ 250,000
Increase in authorized amount for repurchases			$ 250,000
Remaining authorized repurchase amount		$ 264,057

Earnings per Share (Details)

Earnings per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Numerator:
Income (loss) from continuing operations	$ 7,261	$ (50,264)
Gain on sales of investment properties	34,519	41,164
Preferred stock dividends	0	(2,362)
Net income (loss) attributable to common shareholders	41,780	(11,462)
Earnings allocated to unvested restricted shares	(96)	(90)
Net income (loss) attributable to common shareholders excluding amounts attributable to unvested restricted shares	$ 41,684	$ (11,552)
Denominator for earnings (loss) per common share – basic:
Weighted average number of common shares outstanding	218,849	236,294
Effect of dilutive securities:
Stock options	0	0
RSUs	554	0
Denominator for earnings (loss) per common share – diluted:
Weighted average number of common and common equivalent shares outstanding	219,403	236,294
Earnings Per Share, Other Disclosures
Weighted average number of shares of restricted common stock	573	565
Antidilutive Securities Excluded from Computation of Earnings per Share [Line Items]
Number of outstanding options to purchase shares of common stock	38	41
Weighted average exercise price of outstanding options (in dollars per share)	$ 18.85	$ 19.25
Restricted shares
Earnings Per Share, Other Disclosures
Unvested restricted common stock	545	534	496
Stock options
Antidilutive Securities Excluded from Computation of Earnings per Share [Line Items]
Number of outstanding options to purchase shares of common stock that would be anti-dilutive	38	41
Weighted average exercise price of outstanding options excluded from diluted EPS calculation (in dollars per share)	$ 18.85	$ 19.25
RSUs
Earnings Per Share, Other Disclosures
Unvested restricted common stock	649		555
Antidilutive Securities Excluded from Computation of Earnings per Share [Line Items]
Number of RSUs eligible for future conversion	649	644
Weighted average number of RSUs	686	638

Provision for Impairment of I55

Provision for Impairment of Investment Properties - Impairment Indicators (Details) - property	Mar. 31, 2018	Mar. 31, 2017
Impaired Long-Lived Assets Held and Used [Line Items]
Number of properties for which indicators of impairment were identified	4	8
Number of properties for which an impairment charge was recorded	2	0
Number of properties held for sale with impairment indicators but not impaired	0	4
Remaining properties for which indicators of impairment were identified but no impairment was considered necessary	2	4
Weighted average percentage by which projected undiscounted cash flows exceeded carrying value for each of the remaining properties	39.00%	17.00%
Number of properties with impairment indicators which were subsequently sold	1	5

Provision for Impairment of I56

Provision for Impairment of Investment Properties - Impairment Charges (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2018USD ($)ft²	Mar. 31, 2017USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Provision for impairment of investment properties	$ 592	$ 0
Estimated fair value of impaired properties as of impairment date	$ 70,250
Schaumburg Towers
Impaired Long-Lived Assets Held and Used [Line Items]
Square footage | ft²	895,400
Provision for impairment of investment properties	$ 392
CVS Pharmacy - Lawton, OK
Impaired Long-Lived Assets Held and Used [Line Items]
Square footage | ft²	10,900
Provision for impairment of investment properties	$ 200

Fair Value Measurements - Fair

Fair Value Measurements - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Financial liabilities:
Mortgages payable, net	$ 275,316	$ 287,068
Unsecured notes payable, net	695,902	695,748
Unsecured term loans, net	547,629	547,270
Unsecured revolving line of credit	91,000	216,000
Carrying value
Financial assets:
Derivative asset	3,840	1,086
Financial liabilities:
Mortgages payable, net	275,316	287,068
Unsecured notes payable, net	695,902	695,748
Unsecured term loans, net	547,629	547,270
Unsecured revolving line of credit	91,000	216,000
Fair value
Financial assets:
Derivative asset	3,840	1,086
Financial liabilities:
Mortgages payable, net	282,063	298,635
Unsecured notes payable, net	679,372	693,823
Unsecured term loans, net	552,364	552,555
Unsecured revolving line of credit	$ 91,247	$ 216,222

Fair Value Measurements - Recur

Fair Value Measurements - Recurring Fair Value Measurements (Details) - Recurring Fair Value Measurements - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value Measurements [Line Items]
Derivative asset	$ 3,840	$ 1,086
Fair value, Level 2
Fair Value Measurements [Line Items]
Derivative asset	$ 3,840	$ 1,086

Fair Value Measurements - Nonre

Fair Value Measurements - Nonrecurring Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Sep. 30, 2017
Fair Value Measurements [Line Items]
Provision for impairment	$ 592	$ 0
Nonrecurring Fair Value Measurements
Fair Value Measurements [Line Items]
Fair value of investment properties	1,600		$ 74,250
Provision for impairment	200		50,077
Fair value, Level 2 | Nonrecurring Fair Value Measurements
Fair Value Measurements [Line Items]
Fair value of investment properties	1,600		74,250
Investment properties held for sale | Nonrecurring Fair Value Measurements
Fair Value Measurements [Line Items]
Fair value of investment properties	68,650
Provision for impairment	392
Investment properties held for sale | Fair value, Level 2 | Nonrecurring Fair Value Measurements
Fair Value Measurements [Line Items]
Fair value of investment properties	68,650
Schaumburg Towers
Fair Value Measurements [Line Items]
Fair value of investment properties	68,650			$ 58,000
Sales price	$ 86,600		87,600
Home Depot Plaza
Fair Value Measurements [Line Items]
Fair value of investment properties			$ 16,250

Fair Value Measurements - Fai60

Fair Value Measurements - Fair Value Disclosures (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Fair Value Measurements [Line Items]
Mortgages payable, net	$ 275,316	$ 287,068
Unsecured notes payable, net	695,902	695,748
Unsecured term loans, net	547,629	547,270
Unsecured revolving line of credit	91,000	216,000
Fair value, Level 1
Fair Value Measurements [Line Items]
Unsecured notes payable, net	236,818	243,183
Fair value, Level 3
Fair Value Measurements [Line Items]
Mortgages payable, net	282,063	298,635
Unsecured notes payable, net	442,554	450,640
Unsecured term loans, net	552,364	552,555
Unsecured revolving line of credit	91,247	216,222
Fair value, Total
Fair Value Measurements [Line Items]
Mortgages payable, net	282,063	298,635
Unsecured notes payable, net	679,372	693,823
Unsecured term loans, net	552,364	552,555
Unsecured revolving line of credit	$ 91,247	$ 216,222
Mortgages payable | Minimum
Fair Value Measurements [Line Items]
Discount rate (as a percent)	3.70%	3.50%
Mortgages payable | Maximum
Fair Value Measurements [Line Items]
Discount rate (as a percent)	4.40%	4.20%
Unsecured notes payable
Fair Value Measurements [Line Items]
Unsecured notes payable, net	$ 700,000	$ 700,000
Unsecured term loans | Weighted average
Fair Value Measurements [Line Items]
Discount rate (as a percent)	1.33%	1.33%
Unsecured revolving line of credit
Fair Value Measurements [Line Items]
Discount rate (as a percent)	1.20%	1.30%
Notes Due 2021, 2024, 2026 and 2028 | Unsecured notes payable | Weighted average
Fair Value Measurements [Line Items]
Discount rate (as a percent)	4.69%	4.28%

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Commitments and Contingencies [Line Items]
Amount of letters of credit outstanding	$ 9,645
Aggregate proceeds, net	112,214	$ 104,527
Reisterstown Road Plaza
Commitments and Contingencies [Line Items]
Redevelopment costs incurred	8,447
Reisterstown Road Plaza | Minimum
Commitments and Contingencies [Line Items]
Net estimated redevelopment costs	9,500
Reisterstown Road Plaza | Maximum
Commitments and Contingencies [Line Items]
Net estimated redevelopment costs	10,500
Circle East
Commitments and Contingencies [Line Items]
Redevelopment costs incurred	3,409
Aggregate proceeds, net	11,820
Circle East | Minimum
Commitments and Contingencies [Line Items]
Net estimated redevelopment costs	33,000
Circle East | Maximum
Commitments and Contingencies [Line Items]
Net estimated redevelopment costs	$ 35,000

Subsequent Events (Details)

Subsequent Events (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	May 02, 2018USD ($)ft²$ / shares	Mar. 31, 2018$ / shares	Mar. 31, 2017$ / shares	Dec. 31, 2017USD ($)
Subsequent Event [Line Items]
Common stock dividends declared (per share) | $ / shares		$ 0.165625	$ 0.165625
Unsecured credit facility term loan due 2018
Subsequent Event [Line Items]
Repayment of unsecured term loan				$ 100,000
Subsequent events | Unsecured Credit Facility | 2018 Wells Fargo and KeyBank Syndicate
Subsequent Event [Line Items]
Aggregate borrowing capacity	$ 1,100,000
Subsequent events | Unsecured credit facility term loan due 2018
Subsequent Event [Line Items]
Repayment of unsecured term loan	$ 100,000
Subsequent events | CVS Pharmacy - Lawton, OK
Subsequent Event [Line Items]
Square footage | ft²	10,900
Sales price	$ 1,600
Subsequent events | Class A common stock
Subsequent Event [Line Items]
Common stock dividends declared (per share) | $ / shares	$ 0.165625