Retail Properties of America (RPAI) 10-Q 5 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	1-May-15
Entity Information
Entity Registrant Name	RETAIL PROPERTIES OF AMERICA, INC.
Entity Central Index Key	1222840
Document Type	10-Q
Document Period End Date	31-Mar-15
Amendment Flag	FALSE
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		237,186,483

Condensed_Consolidated_Balance

Condensed Consolidated Balance Sheets (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Investment properties:
Land	$1,297,067	$1,195,369
Building and other improvements	4,652,456	4,442,446
Developments in progress	42,983	42,561
Gross investment properties	5,992,506	5,680,376
Less accumulated depreciation	-1,411,423	-1,365,471
Net investment properties	4,581,083	4,314,905
Cash and cash equivalents	64,895	112,292
Accounts and notes receivable (net of allowances of $7,660 and $7,497, respectively)	77,937	86,013
Acquired lease intangible assets, net	151,437	125,490
Assets associated with investment properties held for sale	5,041	33,640
Other assets, net	112,817	131,520
Total assets	4,993,210	4,803,860
Liabilities:
Mortgages payable, net	1,560,956	1,634,465
Unsecured notes payable, net	498,822	250,000
Unsecured term loan	450,000	450,000
Unsecured revolving line of credit	35,000	0
Accounts payable and accrued expenses	54,563	61,129
Distributions payable	39,284	39,187
Acquired lease intangible liabilities, net	117,502	100,641
Liabilities associated with investment properties held for sale	320	8,203
Other liabilities	75,575	70,860
Total liabilities	2,832,022	2,614,485
Commitments and contingencies (Note 14)
Equity:
Additional paid-in capital	4,923,342	4,922,864
Accumulated distributions in excess of earnings	-2,763,258	-2,734,688
Accumulated other comprehensive loss	-632	-537
Total shareholders' equity	2,159,694	2,187,881
Noncontrolling interests	1,494	1,494
Total equity	2,161,188	2,189,375
Total liabilities and equity	4,993,210	4,803,860
7.00% Series A cumulative redeemable preferred stock
Equity:
Preferred stock	5	5
Class A common stock
Equity:
Common stock	$237	$237

Condensed_Consolidated_Balance1

Condensed Consolidated Balance Sheets (parenthetical) (USD $)	3 Months Ended	12 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Accounts and notes receivable, allowances (in dollars)	$7,660	$7,497
7.00% Series A cumulative redeemable preferred stock
Preferred stock, par value (in dollars per share)	$0.00	$0.00
Preferred stock, shares authorized	10,000	10,000
Preferred stock, dividend rate	7.00%	7.00%
Preferred stock, shares issued	5,400	5,400
Preferred stock, shares outstanding	5,400	5,400
Preferred stock, liquidation preference	$135,000	$135,000
Class A common stock
Common stock, par value (in dollars per share)	$0.00	$0.00
Common stock, shares authorized	475,000	475,000
Common stock, shares issued	237,186	236,602
Common stock, shares outstanding	237,186	236,602

Condensed_Consolidated_Stateme

Condensed Consolidated Statements of Operations and Other Comprehensive Income (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Revenues:
Rental income	$119,788		$117,531
Tenant recovery income	31,300		29,748
Other property income	2,109		1,912
Total revenues	153,197		149,191
Expenses:
Property operating expenses	25,695		26,526
Real estate taxes	20,510		18,414
Depreciation and amortization	54,676		53,830
Provision for impairment of investment properties	0		394
General and administrative expenses	10,992		8,450
Total expenses	111,873		107,614
Operating income	41,324		41,577
Gain on extinguishment of other liabilities	0		4,258
Equity in loss of unconsolidated joint ventures, net	0		-778
Interest expense	-34,045		-31,863
Other income, net	1,225		427
Income from continuing operations	8,504		13,621
Discontinued operations:
Loss, net	0		-148
Gain on sales of investment properties	0		655
Income from discontinued operations	0		507
Gain on sales of investment properties	4,572		0
Net income	13,076		14,128
Net income attributable to the Company	13,076		14,128
Preferred stock dividends	-2,362		-2,362
Net income attributable to common shareholders	10,714		11,766
Earnings per common share b basic and diluted:
Continuing operations	$0.05		$0.05
Discontinued operations	$0		$0
Net income per common share attributable to common shareholders	$0.05		$0.05
Net income	13,076		14,128
Other comprehensive loss:
Net unrealized loss on derivative instruments (Note 9)	-95		-18
Comprehensive income attributable to the Company	$12,981		$14,110
Weighted average number of common shares outstanding b basic	236,250	[1]	236,151	[2]
Weighted average number of common shares outstanding b diluted	236,253		236,153
[1]	Excludes 871 shares of unvested restricted common stock, which equate to 611 shares on a weighted average basis for the three months ended MarchB 31, 2015. These shares will continue to be excluded from the computation of basic EPS until contingencies are resolved and the shares are released.
[2]	Excludes 414 shares of unvested restricted common stock, which equate to 264 shares on a weighted average basis for the three months ended MarchB 31, 2014. These shares will continue to be excluded from the computation of basic EPS until contingencies are resolved and the shares are released.

Condensed_Consolidated_Stateme1

Condensed Consolidated Statements of Equity (USD $)	Total	Preferred stock	Common stock	Additional paid-in capital	Accumulated distributions in excess of earnings	Accumulated other comprehensive loss	Total shareholders' equity	Noncontrolling interests
In Thousands, unless otherwise specified		7.00% Series A cumulative redeemable preferred stock	Class A common stock
Balance at Dec. 31, 2013	$2,308,834	$5	$236	$4,919,633	($2,611,796)	($738)	$2,307,340	$1,494
Balance (in shares) at Dec. 31, 2013		5,400	236,302
Increase (Decrease) in Shareholders' Equity
Net income	14,128				14,128		14,128
Other comprehensive loss	-18					-18	-18
Distributions declared to preferred shareholders	-2,362				-2,362		-2,362
Distributions declared to common shareholders	-39,181				-39,181		-39,181
Issuance of common stock, net of offering costs	-37			-37			-37
Issuance of restricted common stock	1		1				1
Issuance of restricted common stock (in shares)			262
Stock-based compensation expense, net of shares withheld for employee taxes and forfeitures	589			589			589
Balance at Mar. 31, 2014	2,281,954	5	237	4,920,185	-2,639,211	-756	2,280,460	1,494
Balance (in shares) at Mar. 31, 2014		5,400	236,564
Balance at Dec. 31, 2014	2,189,375	5	237	4,922,864	-2,734,688	-537	2,187,881	1,494
Balance (in shares) at Dec. 31, 2014		5,400	236,602
Increase (Decrease) in Shareholders' Equity
Net income	13,076				13,076		13,076
Other comprehensive loss	-95					-95	-95
Distributions declared to preferred shareholders	-2,362				-2,362		-2,362
Distributions declared to common shareholders	-39,284				-39,284		-39,284
Issuance of common stock, net of offering costs	-40			-40			-40
Issuance of restricted common stock	0		0				0
Issuance of restricted common stock (in shares)			637
Stock-based compensation expense, net of shares withheld for employee taxes and forfeitures	518			518			518
Stock-based compensation expense, net of shares withheld for employee taxes and forfeitures (in shares)			-53
Balance at Mar. 31, 2015	$2,161,188	$5	$237	$4,923,342	($2,763,258)	($632)	$2,159,694	$1,494
Balance (in shares) at Mar. 31, 2015		5,400	237,186

Condensed_Consolidated_Stateme2

Condensed Consolidated Statements of Equity (parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Distributions declared to preferred shareholders (in dollars per share)	$0.44	$0.44
Distributions declared to common shareholders (in dollars per share)	$0.17	$0.17

Condensed_Consolidated_Stateme3

Condensed Consolidated Statements of Cash Flows (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net income	$13,076	$14,128
Adjustments to reconcile net income to net cash provided by operating activities (including discontinued operations):
Depreciation and amortization	54,676	53,830
Provision for impairment of investment properties	0	394
Gain on sales of investment properties	-4,572	-655
Gain on extinguishment of other liabilities	0	-4,258
Amortization of loan fees and debt premium and discount, net	992	1,599
Amortization of stock-based compensation	1,369	589
Premium paid in connection with defeasance of mortgages payable	2,604	0
Equity in loss of unconsolidated joint ventures, net	0	778
Distributions on investments in unconsolidated joint ventures	0	755
Payment of leasing fees and inducements	-1,539	-2,277
Changes in accounts receivable, net	10,286	5,945
Changes in accounts payable and accrued expenses, net	-12,714	-10,808
Changes in other operating assets and liabilities, net	6,356	-1,164
Other, net	593	-705
Net cash provided by operating activities	71,127	58,151
Cash flows from investing activities:
Changes in restricted escrows, net	17,673	1,499
Purchase of investment properties	-316,200	-28,324
Capital expenditures and tenant improvements	-10,946	-9,558
Proceeds from sales of investment properties	35,343	9,204
Investment in developments in progress	-380	-1,441
Investment in unconsolidated joint ventures	0	-25
Other, net	-25	0
Net cash used in investing activities	-274,535	-28,645
Cash flows from financing activities:
Proceeds from mortgages payable	322	1,622
Principal payments on mortgages payable	-71,505	-50,114
Proceeds from unsecured notes payable	248,815	0
Proceeds from unsecured credit facility	335,000	101,000
Repayments of unsecured credit facility	-300,000	-36,000
Payment of loan fees and deposits, net	-1,812	0
Purchase of Treasury securities in connection with defeasance of mortgages payable	-12,379	0
Distributions paid	-41,549	-41,500
Other, net	-881	-37
Net cash provided by (used in) financing activities	156,011	-25,029
Net (decrease) increase in cash and cash equivalents	-47,397	4,477
Cash and cash equivalents, at beginning of period	112,292	58,190
Cash and cash equivalents, at end of period	64,895	62,667
Supplemental cash flow disclosure, including non-cash activities:
Cash paid for interest	24,662	26,813
Distributions payable	39,284	39,181
Accrued capital expenditures and tenant improvements	4,474	5,217
Accrued leasing fees and inducements	533	338
Accrued development expenditures	133	429
Treasury securities transferred in connection with defeasance of mortgages payable	12,379	0
Defeasance of mortgages payable	9,775	0
Purchase of investment properties (after credits at closing):
Land, building and other improvements, net	-308,728	-28,112
Accounts receivable, acquired lease intangible and other assets	-34,929	-1,492
Accounts payable, acquired lease intangible and other liabilities	27,457	1,280
Purchase of investment properties (after credits at closing)	-316,200	-28,324
Proceeds from sales of investment properties:
Land, building and other improvements, net	30,582	8,079
Accounts receivable, acquired lease intangible and other assets	207	494
Accounts payable, acquired lease intangible and other liabilities	-50	-24
Deferred gain	32	0
Gain on sales of investment properties	4,572	655
Proceeds from sales of investment properties	$35,343	$9,204

Organization_and_Basis_of_Pres

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2015
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 to own and operate high quality, strategically located shopping centers in the United States.
	All share amounts and dollar amounts in this Quarterly Report are stated in thousands with the exception of per share amounts and per square foot amounts.
	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 shareholders. If the Company fails to qualify as a REIT in any taxable year, the Company will be subject to U.S. federal corporate income tax on its undistributed 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 as a result of 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 those estimates.
	The accompanying condensed consolidated financial statements include the accounts of the Company, as well as all wholly-owned subsidiaries and consolidated joint venture investments. Wholly-owned subsidiaries generally consist of limited liability companies (LLCs), limited partnerships and statutory trusts.
	The Company’s property ownership as of March 31, 2015 is summarized below:
		Wholly-owned	Consolidated
			Joint Ventures (a)
	Operating properties (b)	216	—
	Development properties	2	1
	(a)	The Company has a 50% ownership interest in one LLC.
	(b)	Excludes one wholly-owned property classified as held for sale as of March 31, 2015.
	As of March 31, 2015, the Company is the controlling member in one less-than-wholly-owned consolidated entity. The Company is entitled to a preferred return on its capital contributions to the entity. No adjustments to the carrying value of the noncontrolling interests for contributions, distributions or allocation of net income or loss were made during the three months ended March 31, 2015 and 2014.
	During the three months ended March 31, 2014, the Company held investments in MS Inland Fund, LLC (MS Inland) and Oak Property & Casualty LLC (Oak), which were unconsolidated joint ventures accounted for under the equity method of accounting. The Company dissolved MS Inland and terminated its participation in Oak prior to December 31, 2014. The Company recorded net equity in loss of unconsolidated joint ventures of $778 and received net cash distributions of $730 during the three months ended March 31, 2014.

Summary_of_Significant_Account

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies
	Refer to the Company’s 2014 Annual Report on Form 10-K for a summary of the Company’s 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, 2015.
	Recent Accounting Pronouncements
	Effective January 1, 2016 with early adoption permitted, the concept of extraordinary items will be eliminated from GAAP and entities will no longer be required to consider whether an underlying event or transaction is extraordinary. However, the presentation and disclosure guidance for items that are unusual in nature or occur infrequently will be retained. The Company has elected to early adopt this pronouncement effective January 1, 2015. The adoption of this pronouncement did not have any effect on the Company’s condensed consolidated financial statements.
	Effective January 1, 2016 with early adoption permitted, companies will be required to present debt issuance costs related to a recognized debt liability as a direct deduction from the carrying amount of that debt liability on the balance sheet. The recognition and measurement guidance for debt issuance costs will not be affected. This pronouncement requires a full retrospective method of adoption and the adoption will result in the reclassification of unamortized capitalized loan fees from other assets to a direct reduction of the Company’s indebtedness on the condensed consolidated balance sheets.
	Effective January 1, 2016 with early adoption permitted, a company’s management will be required to assess the entity’s ability to continue as a going concern every reporting period including interim periods for a period of one year after the date that the financial statements are issued (or available to be issued) and provide certain disclosures if conditions or events raise substantial doubt about the entity’s ability to continue as a going concern. The Company does not expect the adoption of this pronouncement will have a material effect on its condensed consolidated financial statements.
	Effective January 1, 2016 with early adoption permitted, companies will be required to evaluate whether they should consolidate certain legal entities under a revised consolidation model. All legal entities are subject to reevaluation under the revised consolidation model, which modifies the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities, eliminates the presumption that a general partner should consolidate a limited partnership, affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships, and provides a scope exception from consolidation guidance for registered money market funds. This pronouncement allows either a full or a modified retrospective method of adoption. The Company does not expect the adoption of this pronouncement will have a material effect on its condensed consolidated financial statements.
	Effective January 1, 2017 and currently awaiting Financial Accounting Standards Board approval of a proposal which could potentially defer the effective date by one year to January 1, 2018, companies will be required to apply a five-step model in accounting for revenue arising from contracts with customers. The core principle of this revised revenue model is that a company 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. Lease contracts will be excluded from this revenue recognition criteria; however, the sale of real estate will be required to follow the new model. This pronouncement allows either a full or a modified retrospective method of adoption. Expanded quantitative and qualitative disclosures regarding revenue recognition will be required for contracts that are subject to this guidance. The Company does not expect the adoption of this pronouncement will have a material effect on its condensed consolidated financial statements; however, it will continue to evaluate this assessment until the guidance becomes effective.

Acquisitions

Acquisitions	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Acquisitions	Acquisitions
	The Company closed on the following acquisitions during the three months ended March 31, 2015:
	Date		Property Name		Metropolitan	Property Type		Square	Acquisition
					Statistical Area			Footage	Price
					(MSA)
	8-Jan-15		Downtown Crown		Washington, D.C.	Multi-tenant retail		258,000	$	162,785
	23-Jan-15		Merrifield Town Center		Washington, D.C.	Multi-tenant retail		85,000	56,500
	23-Jan-15		Fort Evans Plaza II		Washington, D.C.	Multi-tenant retail		229,000	65,000
	19-Feb-15		Cedar Park Town Center		Austin	Multi-tenant retail		179,000	39,057
	24-Mar-15		Lake Worth Towne Crossing - Parcel (a)		Dallas	Land		—	400
								751,000	$	323,742
	(a)	The Company acquired a parcel located at its Lake Worth Towne Crossing multi-tenant retail operating property.
	The Company closed on the following acquisitions during the three months ended March 31, 2014:
	Date		Property Name		MSA	Property Type		Square	Acquisition
								Footage	Price
	27-Feb-14		Heritage Square		Seattle	Multi-tenant retail		53,100	$	18,022
	27-Feb-14		Bed Bath & Beyond Plaza - Fee Interest (a)		Miami	Ground lease interest		—	10,350
								53,100	$	28,372
	(a)	The Company acquired the fee interest in an existing wholly-owned multi-tenant retail operating property located in Miami, Florida, which was previously subject to a ground lease with a third party. In conjunction with this transaction, the Company reversed a straight-line ground rent liability of $4,258, which is presented in “Gain on extinguishment of other liabilities” in the accompanying consolidated statements of operations and other comprehensive income.
	The following table summarizes the acquisition date fair values, before prorations, the Company recorded in conjunction with the acquisitions discussed above:
			Three Months Ended March 31,
			2015			2014
	Land		$	102,487		$	16,727
	Building and other improvements		206,241			11,385
	Acquired lease intangible assets (a)		33,631			1,492
	Acquired lease intangible liabilities (b)		(18,617		)	(1,232		)
	Net assets acquired		$	323,742		$	28,372
	(a)	The weighted average amortization period for acquired lease intangible assets is 16 years and six years for acquisitions completed during the three months ended March 31, 2015 and 2014, respectively.
	(b)	The weighted average amortization period for acquired lease intangible liabilities is 20 years and 12 years for acquisitions completed during the three months ended March 31, 2015 and 2014, respectively.
	The above acquisitions were funded using a combination of available cash on hand and proceeds from the Company’s unsecured revolving line of credit. Transaction costs totaling $911 and $98 for the three months ended March 31, 2015 and 2014, respectively, were expensed as incurred and included within “General and administrative expenses” in the accompanying condensed consolidated statements of operations and other comprehensive income.
	Included in the Company’s condensed consolidated statements of operations and other comprehensive income from the properties acquired are $4,675 and $161 in total revenues and $1,401 and $61 in net income attributable to common shareholders from the date of acquisition through March 31, 2015 and 2014, respectively.
	Subsequent to March 31, 2015, the Company acquired Tysons Corner, a multi-tenant retail property located in the Washington, D.C. MSA, for a gross purchase price of $31,556. The property was acquired on May 4, 2015 and contains approximately 38,000 square feet. The Company has not completed the allocation of the acquisition date fair value for Tysons Corner; however, it expects that the purchase price of this property will primarily be allocated to building, land, and acquired lease intangibles.
	Condensed Pro Forma Financial Information
	The results of operations of the acquisitions accounted for as business combinations are included in the following unaudited condensed pro forma financial information as if these acquisitions had been completed as of the beginning of the year prior to the acquisition date. The following unaudited condensed pro forma financial information is presented as if the 2015 acquisitions, including the Tysons Corner acquisition, were completed as of January 1, 2014, and the 2014 acquisitions were completed as of January 1, 2013. The results of operations associated with the 2015 Lake Worth Towne Crossing and 2014 Bed Bath & Beyond Plaza acquisitions have not been included in the pro forma presentation as they have been accounted for as asset acquisitions. These pro forma results are for comparative purposes only and are not necessarily indicative of what the actual results of operations of the Company would have been had the acquisitions occurred at the beginning of the periods presented, nor are they necessarily indicative of future operating results.
	The unaudited condensed pro forma financial information is as follows:
			Three Months Ended March 31,
			2015			2014
	Total revenues		$	154,484		$	153,847
	Net income		$	12,990		$	13,252
	Net income attributable to common shareholders		$	10,628		$	10,890
	Earnings per common share — basic and diluted
	Net income per common share attributable to common shareholders		$	0.04		$	0.05
	Weighted average number of common shares outstanding — basic		236,250			236,151

Dispositions

Dispositions	3 Months Ended
	Mar. 31, 2015
Discontinued Operations and Disposal Groups [Abstract]
Dispositions	Dispositions
	The Company monitors its investment properties to ensure that each property continues to meet investment and strategic objectives. This approach results in the sale of certain non-strategic and non-core assets that no longer meet the Company’s investment criteria.
	The Company closed on the following property dispositions during the three months ended March 31, 2015:
	Date		Property Name		Property Type		Square		Consideration		Aggregate		Gain
							Footage				Proceeds, Net (a)
	January 20, 2015		Aon Hewitt East Campus		Single-user office		343,000		$	17,233	$	16,495	$	—
	February 27, 2015		Promenade at Red Cliff		Multi-tenant retail		94,500		19,050		18,848		4,572
							437,500		$	36,283	$	35,343	$	4,572
	(a)	Aggregate proceeds are net of transaction costs.
	The Company closed on the following property disposition during the three months ended March 31, 2014:
	Date		Property Name		Property Type		Square		Consideration		Aggregate		Gain
							Footage				Proceeds, Net (a)
	March 11, 2014		Riverpark Phase IIA		Single-user retail		64,300		$	9,269	$	9,204	$	655
	(a)	Aggregate proceeds are net of transaction costs.
	As of March 31, 2015, the Company had entered into a contract to sell Hartford Insurance Building, a 97,400 square foot single-user office property located in Maple Grove, Minnesota. This property qualified for held for sale accounting treatment upon meeting all applicable GAAP criteria during the quarter ended March 31, 2015, at which time depreciation and amortization were ceased. As such, the assets and liabilities associated with this property are separately classified as held for sale in the condensed consolidated balance sheet as of March 31, 2015. Promenade at Red Cliff and Aon Hewitt East Campus, both of which were sold during the three months ended March 31, 2015, were classified as held for sale as of December 31, 2014.
	The following table presents the assets and liabilities associated with the investment properties classified as held for sale:
		March 31,				December 31,
		2015				2014
	Assets
	Land, building and other improvements	$	4,972			$	36,020
	Accumulated depreciation	(58		)		(5,358		)
	Net investment properties	4,914				30,662
	Other assets	127				2,978
	Assets associated with investment properties held for sale	$	5,041			$	33,640
	Liabilities
	Mortgage payable	$	—			$	8,075
	Other liabilities	320				128
	Liabilities associated with investment properties held for sale	$	320			$	8,203
	There was no activity during the three months ended March 31, 2015 related to discontinued operations. The results of operations for the three months ended March 31, 2014 for the investment property accounted for as discontinued operations, Riverpark Phase IIA which was classified as held for sale as of December 31, 2013, were immaterial.

Compensation_Plans

Compensation Plans	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Compensation Plans	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, 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 represents a summary of the Company’s unvested restricted shares as of and for the three months ended March 31, 2015:
		Unvested		Weighted Average
		Restricted		Grant Date Fair
		Shares		Value per
				Restricted Share
	Balance as of January 1, 2015	396		$	14.26
	Shares granted (a)	637		$	16.02
	Shares vested	(162	)	$	14.03
	Balance as of March 31, 2015	871		$	15.59
	(a)	Shares granted vest ratably over periods ranging from one to three years in accordance with the terms of applicable award documents.
	During the three months ended March 31, 2015 and 2014, the Company recorded compensation expense of $1,369 and $587, respectively, related to unvested restricted shares. As of March 31, 2015, total unrecognized compensation expense related to unvested restricted shares was $10,919, which is expected to be amortized over a weighted average term of 1.5 years. The total fair value of shares vested during the three months ended March 31, 2015 was $2,613.
	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, 2015, options to purchase 84 shares of common stock had been granted, of which options to purchase three shares had been exercised, options to purchase six shares had expired and options to purchase 11 shares had been forfeited. The Company did not grant any options in 2014 or 2015 and did not record any compensation expense related to stock options during the three months ended March 31, 2015. Compensation expense of $2 related to stock options was recorded during the three months ended March 31, 2014.

Mortgages_Payable

Mortgages Payable	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Mortgages Payable	Mortgages Payable
	The following table summarizes the Company’s mortgages payable:
		March 31, 2015								December 31, 2014
		Aggregate			Weighted			Weighted		Aggregate				Weighted		Weighted
		Principal			Average			Average Years		Principal				Average		Average Years
		Balance			Interest Rate			to Maturity		Balance				Interest Rate		to Maturity
	Fixed rate mortgages payable (a)	$	1,542,858		6.01	%		3.9		$	1,616,063			6.03	%	4
	Variable rate construction loan (b)	15,222			2.44	%		0.6		14,900				2.44	%	0.8
	Mortgages payable	1,558,080			5.97	%		3.9		1,630,963				5.99	%	3.9
	Premium, net of accumulated amortization	3,218								3,972
	Discount, net of accumulated amortization	(342		)						(470		)
	Mortgages payable, net	$	1,560,956							$	1,634,465
	(a)	Includes $8,070 and $8,124 of variable rate mortgage debt that was swapped to a fixed rate as of March 31, 2015 and December 31, 2014, respectively, and excludes mortgages payable of $8,075 associated with one investment property classified as held for sale as of December 31, 2014. The fixed rate mortgages had interest rates ranging from 3.35% to 8.00% as of March 31, 2015 and December 31, 2014, respectively.
	(b)	The variable rate construction loan bears interest at a floating rate of London Interbank Offered Rate (LIBOR) plus 2.25%.
	Mortgages Payable
	During the three months ended March 31, 2015, the Company repaid or defeased mortgages payable in the total amount of $77,135 (excluding scheduled principal payments of $4,145 related to amortizing loans). The loans repaid or defeased during the three months ended March 31, 2015 had a weighted average fixed interest rate of 6.53%.
	The majority of the Company’s mortgages payable require monthly payments of principal and interest, as well as reserves for real estate taxes and certain other costs. Certain of the Company’s properties and the related tenant leases are pledged as collateral for the fixed rate mortgages payable while a consolidated joint venture property and the related tenant leases are pledged as collateral for the variable rate construction loan. Although the mortgage loans obtained by the Company are generally non-recourse, occasionally, the Company may guarantee all or a portion of the debt on a full-recourse basis. As of March 31, 2015, the Company had guaranteed $8,106 of the outstanding mortgage and construction loans with maturity dates ranging from November 2, 2015 through September 30, 2016 (see Note 14). At times, the Company has borrowed funds financed as part of a cross-collateralized package, with cross-default provisions, in order to enhance the financial benefits of a transaction. In those circumstances, one or more of the Company’s properties may secure the debt of another of the Company’s properties. As of March 31, 2015, the most significant cross-collateralized pool of mortgages was the IW JV 2009, LLC portfolio in the amount of $460,078, which is cross-collateralized by 53 properties.
	Debt Maturities
	The following table shows the scheduled maturities and principal amortization of the Company’s indebtedness as of March 31, 2015 for the remainder of 2015, 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, 2015.
		2015			2016				2017				2018			2019			Thereafter			Total
	Debt:
	Fixed rate debt:
	Mortgages payable (a)	$	305,135		$	67,703			$	321,090			$	12,376		$	501,308		$	335,246		$	1,542,858
	Unsecured credit facility - fixed rate portion of term loan (b)	—			—				—				300,000			—			—			300,000
	Unsecured notes payable (c)	—			—				—				—			—			500,000			500,000
	Total fixed rate debt	305,135			67,703				321,090				312,376			501,308			835,246			2,342,858
	Variable rate debt:
	Construction loan	15,222			—				—				—			—			—			15,222
	Unsecured credit facility	—			—				35,000				150,000			—			—			185,000
	Total variable rate debt	15,222			—				35,000				150,000			—			—			200,222
	Total debt (d)	$	320,357		$	67,703			$	356,090			$	462,376		$	501,308		$	835,246		$	2,543,080
	Weighted average interest rate on debt:
	Fixed rate debt	5.39		%	5.06		%		5.53		%		2.18		%	7.5		%	4.51		%	5.11		%
	Variable rate debt (e)	2.44		%	—				1.68		%		1.63		%	—			—			1.7		%
	Total	5.25		%	5.06		%		5.15		%		2		%	7.5		%	4.51		%	4.84		%
	(a)	Includes $8,070 of variable rate mortgage debt that was swapped to a fixed rate as of March 31, 2015. Excludes mortgage premium of $3,218 and discount of $(342), net of accumulated amortization, which was outstanding as of March 31, 2015.
	(b)	$300,000 of LIBOR-based variable rate debt has been swapped to a fixed rate through February 24, 2016. The swap effectively converts one-month floating rate LIBOR to a fixed rate of 0.53875% over the term of the swap.
	(c)	Excludes discount of $(1,178), net of accumulated amortization, which was outstanding as of March 31, 2015.
	(d)	As of March 31, 2015, the weighted average years to maturity of consolidated indebtedness was 4.7 years.
	(e)	Represents interest rates as of March 31, 2015.
	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, 2015
Debt Disclosure [Abstract]
Unsecured Notes Payable	Unsecured Notes Payable
	On March 12, 2015, the Company completed a public offering of $250,000 in aggregate principal amount of its 4.00% senior unsecured notes due 2025 (4.00% notes). The 4.00% notes were priced at 99.526% of the principal amount to yield 4.058% to maturity. In addition, on June 30, 2014, the Company completed a private placement of $250,000 of unsecured notes, consisting of $100,000 of 4.12% Series A senior notes due 2021 and $150,000 of 4.58% Series B senior notes due 2024 (collectively, Series A and B notes). The proceeds from the 4.00% notes and the Series A and B notes were used to repay a portion of the Company’s unsecured revolving line of credit in anticipation of the repayment of future secured debt maturities.
	The following table summarizes the Company’s unsecured notes payable as of March 31, 2015:
	Unsecured Notes Payable	Maturity Date	Principal Balance			Interest Rate/
						Weighted Average
						Interest Rate
	Senior notes - 4.12% Series A due 2021	30-Jun-21	$	100,000		4.12	%
	Senior notes - 4.58% Series B due 2024	30-Jun-24	150,000			4.58	%
	Senior notes - 4.00% due 2025	15-Mar-25	250,000			4	%
			500,000			4.2	%
	Discount, net of accumulated amortization		(1,178		)
		Total	$	498,822
	The indenture, as supplemented, governing the 4.00% notes (the Indenture) 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.
	The note purchase agreement governing the Series A and B notes 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 primary 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, 2015, management believes the Company was in compliance with the financial covenants under the Indenture and the note purchase agreement.

Unsecured_Credit_Facility

Unsecured Credit Facility	3 Months Ended
	Mar. 31, 2015
Line of Credit Facility [Abstract]
Unsecured Credit Facility	Credit Facility
	On May 13, 2013, the Company entered into its third amended and restated unsecured credit agreement with a syndicate of financial institutions led by KeyBank National Association and Wells Fargo Securities LLC to provide for an unsecured credit facility aggregating $1,000,000. The unsecured credit facility consists of a $550,000 unsecured revolving line of credit and a $450,000 unsecured term loan (collectively, the Unsecured Credit Facility). The Company has the ability to increase available borrowings up to $1,450,000 in certain circumstances.
	The Unsecured Credit Facility is currently priced on a leverage grid at a rate of LIBOR plus a margin ranging from 1.50% to 2.05%, plus a quarterly unused fee ranging from 0.25% to 0.30% depending on the undrawn amount, for the unsecured revolving line of credit and LIBOR plus a margin ranging from 1.45% to 2.00% for the unsecured term loan. The Company received investment grade credit ratings from two rating agencies in 2014. In accordance with the unsecured credit agreement, the Company may elect to convert to an investment grade pricing grid. Upon making such an election and depending on the Company’s credit rating, the interest rate for the unsecured revolving line of credit would equal LIBOR plus a margin ranging from 0.90% to 1.70%, plus a facility fee ranging from 0.15% to 0.35%, and for the unsecured term loan, LIBOR plus a margin ranging from 1.05% to 2.05%. As of March 31, 2015, 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 Company’s Unsecured Credit Facility:
				31-Mar-15				31-Dec-14
	Unsecured Credit Facility		Maturity Date	Balance		Interest Rate/		Balance		Interest Rate/
						Weighted Average				Weighted Average
						Interest Rate				Interest Rate
	Term loan - fixed rate portion (a)		11-May-18	$	300,000	1.99	%	$	300,000	1.99	%
	Term loan - variable rate portion		11-May-18	150,000		1.63	%	150,000		1.62	%
	Revolving line of credit - variable rate		May 12, 2017 (b)	35,000		1.68	%	—		1.67	%
			Total	$	485,000	1.86	%	$	450,000	1.87	%
	(a)	$300,000 of the term loan has been swapped to a fixed rate of 0.53875% plus a margin based on a leverage grid ranging from 1.45% to 2.00% through February 24, 2016. The applicable margin was 1.45% as of March 31, 2015 and December 31, 2014.
	(b)	The Company has a one year extension option on the unsecured revolving line of credit, which it may exercise as long as it is in compliance with the terms of the unsecured credit agreement and it pays an extension fee equal to 0.15% of the commitment amount being extended.
	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; (ii) minimum fixed charge and unencumbered interest coverage ratios; and (iii) a minimum consolidated net worth.
	As of March 31, 2015, management believes the Company was in compliance with the financial covenants and default provisions under the unsecured credit agreement.

Derivatives

Derivatives

3 Months Ended

Mar. 31, 2015

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Derivatives

Derivatives

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.

The Company utilizes two interest rate swaps to hedge the variable cash flows associated with variable rate debt. The effective portion of changes in the fair value of derivatives that are designated and that qualify as cash flow hedges is recorded in “Accumulated other comprehensive loss” and is 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 $607 will be reclassified as an increase to interest expense. The ineffective portion of the change in fair value of derivatives is recognized directly in earnings.

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,

December 31,

March 31,

December 31,

2015

2014

2015

2014

Interest rate swaps

2

2

$

308,070

$

308,124

The table below presents the estimated fair value of the Company’s derivative financial instruments, which are presented within “Other liabilities” in the condensed consolidated balance sheets. The valuation techniques utilized are described in Note 13 to the condensed consolidated financial statements.

Fair Value

March 31,

December 31,

2015

2014

Derivatives designated as cash flow hedges:

Interest rate swaps

$

632

$

562

The following table presents the effect of the Company’s derivative financial instruments on the condensed consolidated statements of operations and other comprehensive income for the three months ended March 31, 2015 and 2014:

Derivatives in

Amount of Loss

Location of Loss

Amount of Loss

Location of Gain

Amount of Gain

Cash Flow

Recognized in Other

Reclassified from

Reclassified from

Recognized In

Recognized in Income

Hedging

Comprehensive Income

Accumulated Other

AOCI into Income

Income on Derivative

on Derivative

Relationships

on Derivative

Comprehensive Income (AOCI)

(Effective Portion)

(Ineffective Portion

(Ineffective Portion and

(Effective Portion)

into Income

and Amount

Amount Excluded from

(Effective Portion)

Excluded from

Effectiveness Testing)

Effectiveness Testing)

2015

2014

2015

2014

2015

2014

Interest rate swaps

$

386

$

309

Interest expense

$

291

$

291

Other income, net

$

(25

)

$

(13

)

Equity

Equity	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Equity	Equity
	In March 2013, the Company established an at-the-market (ATM) equity program under which it may sell shares of its Class A common stock, having an aggregate offering price of up to $200,000, 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. The net proceeds are expected to be used for general corporate purposes, which may include repaying debt, including the Company's unsecured revolving line of credit, and funding acquisitions or other growth initiatives.
	The Company did not sell any shares under its ATM equity program during the three months ended March 31, 2015 and 2014.
	As of March 31, 2015, the Company had Class A common shares having an aggregate offering price of up to $115,165 remaining available for sale under its ATM equity program.

Earnings_per_Share

Earnings per Share	3 Months Ended
	Mar. 31, 2015
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,
		2015				2014
	Numerator:
	Income from continuing operations	$	8,504			$	13,621
	Gain on sales of investment properties	4,572				—
	Preferred stock dividends	(2,362		)		(2,362		)
	Income from continuing operations attributable to common shareholders	10,714				11,259
	Income from discontinued operations	—				507
	Net income attributable to common shareholders	10,714				11,766
	Distributions paid on unvested restricted shares	(66		)		(25		)
	Net income attributable to common shareholders excluding	$	10,648			$	11,741
	amounts attributable to unvested restricted shares
	Denominator:
	Denominator for earnings per common share — basic:
	Weighted average number of common shares outstanding	236,250			(a)	236,151			(b)
	Effect of dilutive securities — stock options	3			(c)	2			(c)
	Denominator for earnings per common share — diluted:
	Weighted average number of common and common equivalent shares outstanding	236,253				236,153
	(a)	Excludes 871 shares of unvested restricted common stock, which equate to 611 shares on a weighted average basis for the three months ended March 31, 2015. These shares will continue to be excluded from the computation of basic EPS until contingencies are resolved and the shares are released.
	(b)	Excludes 414 shares of unvested restricted common stock, which equate to 264 shares on a weighted average basis for the three months ended March 31, 2014. These shares will continue to be excluded from the computation of basic EPS until contingencies are resolved and the shares are released.
	(c)	There were outstanding options to purchase 64 and 78 shares of common stock as of March 31, 2015 and 2014, respectively, at a weighted average exercise price of $19.32 and $19.10, respectively. Of these totals, outstanding options to purchase 54 and 64 shares of common stock as of March 31, 2015 and 2014, respectively, at a weighted average exercise price of $20.72 and $20.71, respectively, have been excluded from the common shares used in calculating diluted earnings per share as including them would be anti-dilutive.

Provision_for_Impairment_of_In

Provision for Impairment of Investment Properties	3 Months Ended
	Mar. 31, 2015
Impairment or Disposal of Tangible Assets Disclosure [Abstract]
Provision for Impairment of Investment Properties	Provision for Impairment of Investment Properties
	As of March 31, 2015 and 2014, 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, 2015 and 2014:
			March 31, 2015			March 31, 2014
	Number of properties for which indicators of impairment were identified		6			12		(a)
	Less: Number of properties for which an impairment charge was recorded		—			1
	Less: Number of properties that were held for sale as of the date the analysis was performed		1		(b)	—
	for which indicators of impairment were identified but no impairment charge was recorded
	Remaining properties for which indicators of impairment were identified		5			11
	Weighted average percentage by which the projected undiscounted cash flows exceeded		66	%		19	%
	its respective carrying value for each of the remaining properties (c)
	(a)	Includes seven properties which were subsequently sold or classified as held for sale as of March 31, 2015.
	(b)	Hartford Insurance Building was classified as held for sale as of March 31, 2015. This property was not considered impaired based upon the executed sales contract and it was sold on April 7, 2015 with an anticipated gain on sale of approximately $860.
	(c)	Based upon the estimated holding period for each asset where an undiscounted cash flow analysis was performed.
	The investment property impairment charge recorded by the Company during the three months ended March 31, 2014 is summarized below:
	Property Name		Property Type		Impairment Date		Square		Provision for
							Footage		Impairment of
									Investment
									Properties
	Midtown Center (a)		Multi-tenant retail		31-Mar-14		408,500		$	394
			Estimated fair value of impaired property as of impairment date						$	47,150
	(a)	The Company recorded an impairment charge based upon the terms and conditions of an executed sales contract for this property, which was sold on April 1, 2014.
	The Company can provide 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, 2015
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, 2015					December 31, 2014
		Carrying Value			Fair Value		Carrying Value			Fair Value
	Financial liabilities:
	Mortgages payable, net	$	1,560,956		$	1,679,271	$	1,634,465		$	1,749,671
	Unsecured notes payable, net	$	498,822		$	519,560	$	250,000		$	258,360
	Unsecured credit facility	$	485,000		$	487,205	$	450,000		$	451,502
	Derivative liability	$	632		$	632	$	562		$	562
	The carrying values of mortgages payable, net and unsecured notes payable, net in the table are included in the condensed consolidated balance sheets under the indicated captions. The carrying value of the Unsecured Credit Facility is comprised of the “Unsecured term loan” and the “Unsecured revolving line of credit” and the carrying value of the derivative liability is included in “Other liabilities” in the 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, 2015
	Derivative liability	$	—		$	632	$	—		$	632
	December 31, 2014
	Derivative liability	$	—		$	562	$	—		$	562
	Derivative liability:  The fair value of the derivative liability is determined using a discounted cash flow analysis on the expected future cash flows of each derivative. This analysis utilizes 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 utilize 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, 2015 and December 31, 2014, 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.
	Nonrecurring Fair Value Measurements
	The Company did not have any assets measured at fair value on a nonrecurring basis as of March 31, 2015.
	The following table presents the Company’s assets measured at fair value on a nonrecurring basis as of December 31, 2014 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 during the year ended December 31, 2014, except for those properties sold prior to December 31, 2014. 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)
	December 31, 2014
	Investment properties	$	—		$	—	$	86,500	(b)	$	86,500	$	59,352
	Investment properties - held for sale (c)	$	—		$	17,233	$	—		$	17,233	$	563
	(a)	Excludes impairment charges recorded on investment properties sold prior to December 31, 2014.
	(b)	Represents the fair values of the Company’s Shaw’s Supermarket, The Gateway, Hartford Insurance Building and Citizen’s Property Insurance Building investment properties. The estimated fair values of Shaw’s Supermarket and The Gateway of $3,100 and $75,400, respectively, were determined using the income approach. The income approach involves discounting the estimated income stream and reversion (presumed sale) value of a property over an estimated holding period to a present value at a risk-adjusted rate. Discount rates, growth assumptions and terminal capitalization rates utilized in this approach are derived from property-specific information, market transactions and other industry data. The terminal capitalization rate and discount rate are significant inputs to this valuation. The following were the key Level 3 inputs used in estimating the fair value of Shaw’s Supermarket and The Gateway as of September 30, 2014.
			2014
			Low	High
	Rental growth rates		Varies (i)	Varies (i)
	Operating expense growth rates		1.39%	3.70%
	Discount rates		8.25%	9.50%
	Terminal capitalization rates		7.50%	8.50%
	(i) Since cash flow models are established at the tenant level, projected rental revenue growth rates fluctuate over the course of the estimated holding period based upon the timing of lease rollover, amount of available space and other property and space-specific factors.
	The estimated fair values of Hartford Insurance Building and Citizen’s Property Insurance Building of $5,000 and $3,000, respectively, were based upon third party comparable sales prices, which contain unobservable inputs used by these third parties to determine the estimated fair values.
	(c)	Represents an impairment charge recorded during the three months ended December 31, 2014 for Aon Hewitt East Campus, which was classified as held for sale as of December 31, 2014. Such charge, calculated as the expected sales price from the executed sales contract less estimated transaction costs as compared to the Company’s carrying value of its investment, was determined to be a Level 2 input. The estimated transaction costs totaling $738 are not reflected as a reduction to the fair value disclosed in the table above but were included in the calculation of the impairment charge.
	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, 2015
	Mortgages payable, net	$	—		$	—	$	1,679,271		$	1,679,271
	Unsecured notes payable, net	$	252,285		$	—	$	267,275		$	519,560
	Unsecured credit facility	$	—		$	—	$	487,205		$	487,205
	December 31, 2014
	Mortgages payable, net	$	—		$	—	$	1,749,671		$	1,749,671
	Unsecured notes payable	$	—		$	—	$	258,360		$	258,360
	Unsecured credit facility	$	—		$	—	$	451,502		$	451,502
	Mortgages payable, net:  The Company estimates the fair value of its mortgages payable by discounting the 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 2.2% to 5.5% and 2.2% to 4.0% as of March 31, 2015 and December 31, 2014, respectively.
	Unsecured notes payable, net: The quoted market price as of March 31, 2015 was used to value the Company’s 4.00% notes. The Company estimates the fair value of its Series A and B notes 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 rate used was 3.59% and 3.97% as of March 31, 2015 and December 31, 2014, respectively.
	Unsecured Credit Facility:  The Company estimates the fair value of its Unsecured Credit Facility by discounting the future cash flows related to the credit spreads at rates currently offered to the Company by its lenders for similar facilities of comparable maturities. 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 1.30% and 1.35% for the unsecured term loan as of March 31, 2015 and December 31, 2014, respectively, and 1.35% for the unsecured revolving line of credit as of March 31, 2015. There were no amounts drawn on the unsecured revolving line of credit as of December 31, 2014.
	There were no transfers between the levels of the fair value hierarchy during the three months ended March 31, 2015.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	Insurance Captive
	On December 1, 2014, the Company formed a wholly-owned captive insurance company, Birch Property and Casualty LLC (Birch), which insures the Company’s first layer of property and general liability insurance claims subject to certain limitations. The Company capitalized Birch in accordance with the applicable regulatory requirements and Birch established annual premiums based on projections derived from the past loss experience of the Company’s properties.
	Guarantees
	Although the mortgage loans obtained by the Company are generally non-recourse, occasionally the Company may guarantee all or a portion of the debt on a full-recourse basis. As of March 31, 2015, the Company has guaranteed $8,106 of its outstanding mortgage and construction loans, with maturity dates ranging from November 2, 2015 through September 30, 2016.

Litigation

Litigation	3 Months Ended
	Mar. 31, 2015
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 condensed consolidated financial statements of the Company.

Subsequent_Events

Subsequent Events	3 Months Ended
	Mar. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events
	Subsequent to March 31, 2015, the Company:
	•	drew $60,000 on its unsecured revolving line of credit and used the proceeds to:
	•	acquire Tysons Corner, a 38,000 square foot multi-tenant retail property located in Vienna, Virginia, for a gross purchase price of $31,556; and
	•	repay a mortgage payable with a principal balance of $21,684 and an interest rate of 8.00%;
	•	closed on the disposition of Hartford Insurance Building, a 97,400 square foot single-user office property located in Maple Grove, Minnesota, for a sales price of $6,015 with an anticipated gain on sale of approximately $860; and
	•	closed on the disposition of Rasmussen College, a 26,700 square foot single-user office property located in Brooklyn Park, Minnesota, for a sales price of $4,800 with an anticipated gain on sale of approximately $1,334.
	On April 27, 2015, the Company’s board of directors declared the cash dividend for the second quarter of 2015 for the Company’s 7.00% Series A cumulative redeemable preferred stock. The dividend of $0.4375 per preferred share will be paid on June 30, 2015 to preferred shareholders of record at the close of business on June 19, 2015.
	On April 27, 2015, the Company’s board of directors declared the distribution for the second quarter of 2015 of $0.165625 per share on the Company’s outstanding Class A common stock, which will be paid on July 10, 2015 to Class A common shareholders of record at the close of business on June 26, 2015.

Summary_of_Significant_Account1

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Recent Accounting Pronouncements	Recent Accounting Pronouncements
	Effective January 1, 2016 with early adoption permitted, the concept of extraordinary items will be eliminated from GAAP and entities will no longer be required to consider whether an underlying event or transaction is extraordinary. However, the presentation and disclosure guidance for items that are unusual in nature or occur infrequently will be retained. The Company has elected to early adopt this pronouncement effective January 1, 2015. The adoption of this pronouncement did not have any effect on the Company’s condensed consolidated financial statements.
	Effective January 1, 2016 with early adoption permitted, companies will be required to present debt issuance costs related to a recognized debt liability as a direct deduction from the carrying amount of that debt liability on the balance sheet. The recognition and measurement guidance for debt issuance costs will not be affected. This pronouncement requires a full retrospective method of adoption and the adoption will result in the reclassification of unamortized capitalized loan fees from other assets to a direct reduction of the Company’s indebtedness on the condensed consolidated balance sheets.
	Effective January 1, 2016 with early adoption permitted, a company’s management will be required to assess the entity’s ability to continue as a going concern every reporting period including interim periods for a period of one year after the date that the financial statements are issued (or available to be issued) and provide certain disclosures if conditions or events raise substantial doubt about the entity’s ability to continue as a going concern. The Company does not expect the adoption of this pronouncement will have a material effect on its condensed consolidated financial statements.
	Effective January 1, 2016 with early adoption permitted, companies will be required to evaluate whether they should consolidate certain legal entities under a revised consolidation model. All legal entities are subject to reevaluation under the revised consolidation model, which modifies the evaluation of whether limited partnerships and similar legal entities are variable interest entities (VIEs) or voting interest entities, eliminates the presumption that a general partner should consolidate a limited partnership, affects the consolidation analysis of reporting entities that are involved with VIEs, particularly those that have fee arrangements and related party relationships, and provides a scope exception from consolidation guidance for registered money market funds. This pronouncement allows either a full or a modified retrospective method of adoption. The Company does not expect the adoption of this pronouncement will have a material effect on its condensed consolidated financial statements.
	Effective January 1, 2017 and currently awaiting Financial Accounting Standards Board approval of a proposal which could potentially defer the effective date by one year to January 1, 2018, companies will be required to apply a five-step model in accounting for revenue arising from contracts with customers. The core principle of this revised revenue model is that a company 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. Lease contracts will be excluded from this revenue recognition criteria; however, the sale of real estate will be required to follow the new model. This pronouncement allows either a full or a modified retrospective method of adoption. Expanded quantitative and qualitative disclosures regarding revenue recognition will be required for contracts that are subject to this guidance. The Company does not expect the adoption of this pronouncement will have a material effect on its condensed consolidated financial statements; however, it will continue to evaluate this assessment until the guidance becomes effective.

Organization_and_Basis_of_Pres1

Organization and Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Summary of property ownership	The Company’s property ownership as of March 31, 2015 is summarized below:
		Wholly-owned	Consolidated
			Joint Ventures (a)
	Operating properties (b)	216	—
	Development properties	2	1
	(a)	The Company has a 50% ownership interest in one LLC.
	(b)	Excludes one wholly-owned property classified as held for sale as of March 31, 2015.

Acquisitions_Tables

Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Schedule of acquisitions	The Company closed on the following acquisitions during the three months ended March 31, 2015:
	Date		Property Name		Metropolitan	Property Type		Square	Acquisition
					Statistical Area			Footage	Price
					(MSA)
	8-Jan-15		Downtown Crown		Washington, D.C.	Multi-tenant retail		258,000	$	162,785
	23-Jan-15		Merrifield Town Center		Washington, D.C.	Multi-tenant retail		85,000	56,500
	23-Jan-15		Fort Evans Plaza II		Washington, D.C.	Multi-tenant retail		229,000	65,000
	19-Feb-15		Cedar Park Town Center		Austin	Multi-tenant retail		179,000	39,057
	24-Mar-15		Lake Worth Towne Crossing - Parcel (a)		Dallas	Land		—	400
								751,000	$	323,742
	(a)	The Company acquired a parcel located at its Lake Worth Towne Crossing multi-tenant retail operating property.
	The Company closed on the following acquisitions during the three months ended March 31, 2014:
	Date		Property Name		MSA	Property Type		Square	Acquisition
								Footage	Price
	27-Feb-14		Heritage Square		Seattle	Multi-tenant retail		53,100	$	18,022
	27-Feb-14		Bed Bath & Beyond Plaza - Fee Interest (a)		Miami	Ground lease interest		—	10,350
								53,100	$	28,372
	(a)	The Company acquired the fee interest in an existing wholly-owned multi-tenant retail operating property located in Miami, Florida, which was previously subject to a ground lease with a third party. In conjunction with this transaction, the Company reversed a straight-line ground rent liability of $4,258, which is presented in “Gain on extinguishment of other liabilities” in the accompanying consolidated statements of operations and other comprehensive income.
Schedule of acquisition date fair values	The following table summarizes the acquisition date fair values, before prorations, the Company recorded in conjunction with the acquisitions discussed above:
			Three Months Ended March 31,
			2015			2014
	Land		$	102,487		$	16,727
	Building and other improvements		206,241			11,385
	Acquired lease intangible assets (a)		33,631			1,492
	Acquired lease intangible liabilities (b)		(18,617		)	(1,232		)
	Net assets acquired		$	323,742		$	28,372
	(a)	The weighted average amortization period for acquired lease intangible assets is 16 years and six years for acquisitions completed during the three months ended March 31, 2015 and 2014, respectively.
	(b)	The weighted average amortization period for acquired lease intangible liabilities is 20 years and 12 years for acquisitions completed during the three months ended March 31, 2015 and 2014, respectively.
Schedule of condensed pro forma financial information	The unaudited condensed pro forma financial information is as follows:
			Three Months Ended March 31,
			2015			2014
	Total revenues		$	154,484		$	153,847
	Net income		$	12,990		$	13,252
	Net income attributable to common shareholders		$	10,628		$	10,890
	Earnings per common share — basic and diluted
	Net income per common share attributable to common shareholders		$	0.04		$	0.05
	Weighted average number of common shares outstanding — basic		236,250			236,151

Dispositions_Tables

Dispositions (Tables)	3 Months Ended
	Mar. 31, 2015
Discontinued Operations and Disposal Groups [Abstract]
Schedule of property dispositions	The Company closed on the following property dispositions during the three months ended March 31, 2015:
	Date		Property Name		Property Type		Square		Consideration		Aggregate		Gain
							Footage				Proceeds, Net (a)
	January 20, 2015		Aon Hewitt East Campus		Single-user office		343,000		$	17,233	$	16,495	$	—
	February 27, 2015		Promenade at Red Cliff		Multi-tenant retail		94,500		19,050		18,848		4,572
							437,500		$	36,283	$	35,343	$	4,572
	(a)	Aggregate proceeds are net of transaction costs.
	The Company closed on the following property disposition during the three months ended March 31, 2014:
	Date		Property Name		Property Type		Square		Consideration		Aggregate		Gain
							Footage				Proceeds, Net (a)
	March 11, 2014		Riverpark Phase IIA		Single-user retail		64,300		$	9,269	$	9,204	$	655
	(a)	Aggregate proceeds are net of transaction costs.
Schedule of assets and liabilities associated with investment properties classified as held for sale	The following table presents the assets and liabilities associated with the investment properties classified as held for sale:
		March 31,				December 31,
		2015				2014
	Assets
	Land, building and other improvements	$	4,972			$	36,020
	Accumulated depreciation	(58		)		(5,358		)
	Net investment properties	4,914				30,662
	Other assets	127				2,978
	Assets associated with investment properties held for sale	$	5,041			$	33,640
	Liabilities
	Mortgage payable	$	—			$	8,075
	Other liabilities	320				128
	Liabilities associated with investment properties held for sale	$	320			$	8,203

Compensation_Plans_Tables

Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Summary of unvested restricted shares	The following table represents a summary of the Company’s unvested restricted shares as of and for the three months ended March 31, 2015:
		Unvested		Weighted Average
		Restricted		Grant Date Fair
		Shares		Value per
				Restricted Share
	Balance as of January 1, 2015	396		$	14.26
	Shares granted (a)	637		$	16.02
	Shares vested	(162	)	$	14.03
	Balance as of March 31, 2015	871		$	15.59
	(a)	Shares granted vest ratably over periods ranging from one to three years in accordance with the terms of applicable award documents.

Mortgages_Payable_Tables

Mortgages Payable (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Summary of mortgages payable	The following table summarizes the Company’s mortgages payable:
		March 31, 2015								December 31, 2014
		Aggregate			Weighted			Weighted		Aggregate				Weighted		Weighted
		Principal			Average			Average Years		Principal				Average		Average Years
		Balance			Interest Rate			to Maturity		Balance				Interest Rate		to Maturity
	Fixed rate mortgages payable (a)	$	1,542,858		6.01	%		3.9		$	1,616,063			6.03	%	4
	Variable rate construction loan (b)	15,222			2.44	%		0.6		14,900				2.44	%	0.8
	Mortgages payable	1,558,080			5.97	%		3.9		1,630,963				5.99	%	3.9
	Premium, net of accumulated amortization	3,218								3,972
	Discount, net of accumulated amortization	(342		)						(470		)
	Mortgages payable, net	$	1,560,956							$	1,634,465
	(a)	Includes $8,070 and $8,124 of variable rate mortgage debt that was swapped to a fixed rate as of March 31, 2015 and December 31, 2014, respectively, and excludes mortgages payable of $8,075 associated with one investment property classified as held for sale as of December 31, 2014. The fixed rate mortgages had interest rates ranging from 3.35% to 8.00% as of March 31, 2015 and December 31, 2014, respectively.
	(b)	The variable rate construction loan bears interest at a floating rate of London Interbank Offered Rate (LIBOR) plus 2.25%.
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, 2015 for the remainder of 2015, 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, 2015.
		2015			2016				2017				2018			2019			Thereafter			Total
	Debt:
	Fixed rate debt:
	Mortgages payable (a)	$	305,135		$	67,703			$	321,090			$	12,376		$	501,308		$	335,246		$	1,542,858
	Unsecured credit facility - fixed rate portion of term loan (b)	—			—				—				300,000			—			—			300,000
	Unsecured notes payable (c)	—			—				—				—			—			500,000			500,000
	Total fixed rate debt	305,135			67,703				321,090				312,376			501,308			835,246			2,342,858
	Variable rate debt:
	Construction loan	15,222			—				—				—			—			—			15,222
	Unsecured credit facility	—			—				35,000				150,000			—			—			185,000
	Total variable rate debt	15,222			—				35,000				150,000			—			—			200,222
	Total debt (d)	$	320,357		$	67,703			$	356,090			$	462,376		$	501,308		$	835,246		$	2,543,080
	Weighted average interest rate on debt:
	Fixed rate debt	5.39		%	5.06		%		5.53		%		2.18		%	7.5		%	4.51		%	5.11		%
	Variable rate debt (e)	2.44		%	—				1.68		%		1.63		%	—			—			1.7		%
	Total	5.25		%	5.06		%		5.15		%		2		%	7.5		%	4.51		%	4.84		%
	(a)	Includes $8,070 of variable rate mortgage debt that was swapped to a fixed rate as of March 31, 2015. Excludes mortgage premium of $3,218 and discount of $(342), net of accumulated amortization, which was outstanding as of March 31, 2015.
	(b)	$300,000 of LIBOR-based variable rate debt has been swapped to a fixed rate through February 24, 2016. The swap effectively converts one-month floating rate LIBOR to a fixed rate of 0.53875% over the term of the swap.
	(c)	Excludes discount of $(1,178), net of accumulated amortization, which was outstanding as of March 31, 2015.
	(d)	As of March 31, 2015, the weighted average years to maturity of consolidated indebtedness was 4.7 years.

Unsecured_Notes_Payable_Tables

Unsecured Notes Payable (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Summary of unsecured notes payable	The following table summarizes the Company’s unsecured notes payable as of March 31, 2015:
	Unsecured Notes Payable	Maturity Date	Principal Balance			Interest Rate/
						Weighted Average
						Interest Rate
	Senior notes - 4.12% Series A due 2021	30-Jun-21	$	100,000		4.12	%
	Senior notes - 4.58% Series B due 2024	30-Jun-24	150,000			4.58	%
	Senior notes - 4.00% due 2025	15-Mar-25	250,000			4	%
			500,000			4.2	%
	Discount, net of accumulated amortization		(1,178		)
		Total	$	498,822

Unsecured_Credit_Facility_Tabl

Unsecured Credit Facility (Tables)	3 Months Ended
	Mar. 31, 2015
Line of Credit Facility [Abstract]
Summary of unsecured credit facility	The following table summarizes the Company’s Unsecured Credit Facility:
				31-Mar-15				31-Dec-14
	Unsecured Credit Facility		Maturity Date	Balance		Interest Rate/		Balance		Interest Rate/
						Weighted Average				Weighted Average
						Interest Rate				Interest Rate
	Term loan - fixed rate portion (a)		11-May-18	$	300,000	1.99	%	$	300,000	1.99	%
	Term loan - variable rate portion		11-May-18	150,000		1.63	%	150,000		1.62	%
	Revolving line of credit - variable rate		May 12, 2017 (b)	35,000		1.68	%	—		1.67	%
			Total	$	485,000	1.86	%	$	450,000	1.87	%
	(a)	$300,000 of the term loan has been swapped to a fixed rate of 0.53875% plus a margin based on a leverage grid ranging from 1.45% to 2.00% through February 24, 2016. The applicable margin was 1.45% as of March 31, 2015 and December 31, 2014.
	(b)	The Company has a one year extension option on the unsecured revolving line of credit, which it may exercise as long as it is in compliance with the terms of the unsecured credit agreement and it pays an extension fee equal to 0.15% of the commitment amount being extended.

Derivatives_Tables

Derivatives (Tables)

3 Months Ended

Mar. 31, 2015

Derivative Instruments and Hedging Activities Disclosure [Abstract]

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,

December 31,

March 31,

December 31,

2015

2014

2015

2014

Interest rate swaps

2

2

$

308,070

$

308,124

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 liabilities” in the condensed consolidated balance sheets. The valuation techniques utilized are described in Note 13 to the condensed consolidated financial statements.

Fair Value

March 31,

December 31,

2015

2014

Derivatives designated as cash flow hedges:

Interest rate swaps

$

632

$

562

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 condensed consolidated statements of operations and other comprehensive income for the three months ended March 31, 2015 and 2014:

Derivatives in

Amount of Loss

Location of Loss

Amount of Loss

Location of Gain

Amount of Gain

Cash Flow

Recognized in Other

Reclassified from

Reclassified from

Recognized In

Recognized in Income

Hedging

Comprehensive Income

Accumulated Other

AOCI into Income

Income on Derivative

on Derivative

Relationships

on Derivative

Comprehensive Income (AOCI)

(Effective Portion)

(Ineffective Portion

(Ineffective Portion and

(Effective Portion)

into Income

and Amount

Amount Excluded from

(Effective Portion)

Excluded from

Effectiveness Testing)

Effectiveness Testing)

2015

2014

2015

2014

2015

2014

Interest rate swaps

$

386

$

309

Interest expense

$

291

$

291

Other income, net

$

(25

)

$

(13

)

Earnings_per_Share_Tables

Earnings per Share (Tables)	3 Months Ended
	Mar. 31, 2015
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,
		2015				2014
	Numerator:
	Income from continuing operations	$	8,504			$	13,621
	Gain on sales of investment properties	4,572				—
	Preferred stock dividends	(2,362		)		(2,362		)
	Income from continuing operations attributable to common shareholders	10,714				11,259
	Income from discontinued operations	—				507
	Net income attributable to common shareholders	10,714				11,766
	Distributions paid on unvested restricted shares	(66		)		(25		)
	Net income attributable to common shareholders excluding	$	10,648			$	11,741
	amounts attributable to unvested restricted shares
	Denominator:
	Denominator for earnings per common share — basic:
	Weighted average number of common shares outstanding	236,250			(a)	236,151			(b)
	Effect of dilutive securities — stock options	3			(c)	2			(c)
	Denominator for earnings per common share — diluted:
	Weighted average number of common and common equivalent shares outstanding	236,253				236,153
	(a)	Excludes 871 shares of unvested restricted common stock, which equate to 611 shares on a weighted average basis for the three months ended March 31, 2015. These shares will continue to be excluded from the computation of basic EPS until contingencies are resolved and the shares are released.
	(b)	Excludes 414 shares of unvested restricted common stock, which equate to 264 shares on a weighted average basis for the three months ended March 31, 2014. These shares will continue to be excluded from the computation of basic EPS until contingencies are resolved and the shares are released.
	(c)	There were outstanding options to purchase 64 and 78 shares of common stock as of March 31, 2015 and 2014, respectively, at a weighted average exercise price of $19.32 and $19.10, respectively. Of these totals, outstanding options to purchase 54 and 64 shares of common stock as of March 31, 2015 and 2014, respectively, at a weighted average exercise price of $20.72 and $20.71, respectively, have been excluded from the common shares used in calculating diluted earnings per share as including them would be anti-dilutive.

Provision_for_Impairment_of_In1

Provision for Impairment of Investment Properties (Tables)	3 Months Ended
	Mar. 31, 2015
Impairment or Disposal of Tangible Assets Disclosure [Abstract]
Schedule of identified impairment indicators	As of March 31, 2015 and 2014, 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, 2015 and 2014:
			March 31, 2015			March 31, 2014
	Number of properties for which indicators of impairment were identified		6			12		(a)
	Less: Number of properties for which an impairment charge was recorded		—			1
	Less: Number of properties that were held for sale as of the date the analysis was performed		1		(b)	—
	for which indicators of impairment were identified but no impairment charge was recorded
	Remaining properties for which indicators of impairment were identified		5			11
	Weighted average percentage by which the projected undiscounted cash flows exceeded		66	%		19	%
	its respective carrying value for each of the remaining properties (c)
	(a)	Includes seven properties which were subsequently sold or classified as held for sale as of March 31, 2015.
	(b)	Hartford Insurance Building was classified as held for sale as of March 31, 2015. This property was not considered impaired based upon the executed sales contract and it was sold on April 7, 2015 with an anticipated gain on sale of approximately $860.
	(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 investment property impairment charge recorded by the Company during the three months ended March 31, 2014 is summarized below:
	Property Name		Property Type		Impairment Date		Square		Provision for
							Footage		Impairment of
									Investment
									Properties
	Midtown Center (a)		Multi-tenant retail		31-Mar-14		408,500		$	394
			Estimated fair value of impaired property as of impairment date						$	47,150
	(a)	The Company recorded an impairment charge based upon the terms and conditions of an executed sales contract for this property, which was sold on April 1, 2014.

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
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, 2015					December 31, 2014
		Carrying Value			Fair Value		Carrying Value			Fair Value
	Financial liabilities:
	Mortgages payable, net	$	1,560,956		$	1,679,271	$	1,634,465		$	1,749,671
	Unsecured notes payable, net	$	498,822		$	519,560	$	250,000		$	258,360
	Unsecured credit facility	$	485,000		$	487,205	$	450,000		$	451,502
	Derivative liability	$	632		$	632	$	562		$	562
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, 2015
	Derivative liability	$	—		$	632	$	—		$	632
	December 31, 2014
	Derivative liability	$	—		$	562	$	—		$	562
Schedule of assets measured at fair value on a nonrecurring basis	The Company did not have any assets measured at fair value on a nonrecurring basis as of March 31, 2015.
	The following table presents the Company’s assets measured at fair value on a nonrecurring basis as of December 31, 2014 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 during the year ended December 31, 2014, except for those properties sold prior to December 31, 2014. 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)
	December 31, 2014
	Investment properties	$	—		$	—	$	86,500	(b)	$	86,500	$	59,352
	Investment properties - held for sale (c)	$	—		$	17,233	$	—		$	17,233	$	563
	(a)	Excludes impairment charges recorded on investment properties sold prior to December 31, 2014.
	(b)	Represents the fair values of the Company’s Shaw’s Supermarket, The Gateway, Hartford Insurance Building and Citizen’s Property Insurance Building investment properties. The estimated fair values of Shaw’s Supermarket and The Gateway of $3,100 and $75,400, respectively, were determined using the income approach. The income approach involves discounting the estimated income stream and reversion (presumed sale) value of a property over an estimated holding period to a present value at a risk-adjusted rate. Discount rates, growth assumptions and terminal capitalization rates utilized in this approach are derived from property-specific information, market transactions and other industry data. The terminal capitalization rate and discount rate are significant inputs to this valuation. The following were the key Level 3 inputs used in estimating the fair value of Shaw’s Supermarket and The Gateway as of September 30, 2014.
			2014
			Low	High
	Rental growth rates		Varies (i)	Varies (i)
	Operating expense growth rates		1.39%	3.70%
	Discount rates		8.25%	9.50%
	Terminal capitalization rates		7.50%	8.50%
	(i) Since cash flow models are established at the tenant level, projected rental revenue growth rates fluctuate over the course of the estimated holding period based upon the timing of lease rollover, amount of available space and other property and space-specific factors.
	The estimated fair values of Hartford Insurance Building and Citizen’s Property Insurance Building of $5,000 and $3,000, respectively, were based upon third party comparable sales prices, which contain unobservable inputs used by these third parties to determine the estimated fair values.
	(c)	Represents an impairment charge recorded during the three months ended December 31, 2014 for Aon Hewitt East Campus, which was classified as held for sale as of December 31, 2014. Such charge, calculated as the expected sales price from the executed sales contract less estimated transaction costs as compared to the Company’s carrying value of its investment, was determined to be a Level 2 input. The estimated transaction costs totaling $738 are not reflected as a reduction to the fair value disclosed in the table above but were included in the calculation of the impairment charge.
Schedule of financial liabilities measured at fair value	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, 2015
	Mortgages payable, net	$	—		$	—	$	1,679,271		$	1,679,271
	Unsecured notes payable, net	$	252,285		$	—	$	267,275		$	519,560
	Unsecured credit facility	$	—		$	—	$	487,205		$	487,205
	December 31, 2014
	Mortgages payable, net	$	—		$	—	$	1,749,671		$	1,749,671
	Unsecured notes payable	$	—		$	—	$	258,360		$	258,360
	Unsecured credit facility	$	—		$	—	$	451,502		$	451,502

Organization_and_Basis_of_Pres2

Organization and Basis of Presentation (Details) (USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014	Dec. 31, 2014
	subsidiary			property
	item
	property
Organization and Basis of Presentation
Number of wholly-owned subsidiaries jointly elected to be treated as a TRS	1
Number of wholly-owned properties classified as held for sale				1
Number of less-than-wholly-owned consolidated entities in which Company is controlling member	1
Equity in loss of unconsolidated joint ventures, net	$0		$778
Net cash distributions from unconsolidated joint ventures			$730
Wholly-owned | Operating properties
Organization and Basis of Presentation
Number of real estate properties owned	216	[1]
Number of wholly-owned properties classified as held for sale	1
Wholly-owned | Development properties
Organization and Basis of Presentation
Number of real estate properties owned	2
Consolidated joint ventures | Development properties
Organization and Basis of Presentation
Number of real estate properties owned	1	[2]
Ownership interest of consolidated joint venture (as a percent)	50.00%
Number of consolidated LLCs in which Company has ownership interest	1
[1]	Excludes one wholly-owned property classified as held for sale as of MarchB 31, 2015.
[2]	The Company has a 50% ownership interest in one LLC.

Acquisitions_Summary_of_Acquis

Acquisitions - Summary of Acquisitions (Details) (USD $)	3 Months Ended		0 Months Ended						1 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Jan. 08, 2015	Jan. 23, 2015	Feb. 19, 2015	Mar. 24, 2015	Feb. 27, 2014	4-May-15	5-May-15
									sqft
Acquisitions
Gain on extinguishment of other liabilities	$0	$4,258
Total revenues	153,197	149,191
Net income attributable to common shareholders	10,714	11,766
Downtown Crown
Acquisitions
Square footage			258,000
Acquisition price			162,785
Merrifield Town Center
Acquisitions
Square footage				85,000
Acquisition price				56,500
Fort Evans Plaza II
Acquisitions
Square footage				229,000
Acquisition price				65,000
Cedar Park Town Center
Acquisitions
Square footage					179,000
Acquisition price					39,057
Parcel at Lake Worth Towne Crossing
Acquisitions
Square footage						0
Acquisition price						400
2015 Acquisitions
Acquisitions
Square footage	751,000
Acquisition price	323,742
Transaction costs	911
Total revenues	4,675
Net income attributable to common shareholders	1,401
Acquisition date fair values:
Land	102,487
Building and other improvements	206,241
Acquired lease intangible assets	33,631
Acquired lease intangible liabilities	-18,617
Net assets acquired	323,742
Weighted average amortization period, acquired lease intangible assets	16 years
Weighted average amortization period, acquired lease intangible liabilities	20 years
Heritage Square
Acquisitions
Square footage							53,100
Acquisition price							18,022
Bed Bath & Beyond Plaza
Acquisitions
Square footage							0
Acquisition price							10,350
Gain on extinguishment of other liabilities							4,258
2014 Acquisitions
Acquisitions
Square footage		53,100
Acquisition price		28,372
Transaction costs		98
Total revenues		161
Net income attributable to common shareholders		61
Acquisition date fair values:
Land		16,727
Building and other improvements		11,385
Acquired lease intangible assets		1,492
Acquired lease intangible liabilities		-1,232
Net assets acquired		28,372
Weighted average amortization period, acquired lease intangible assets		6 years
Weighted average amortization period, acquired lease intangible liabilities		12 years
Tysons Corner | Subsequent events
Acquisitions
Square footage								38,000	38,000
Acquisition price								$31,556	$31,556

Acquisitions_Condensed_Pro_For

Acquisitions - Condensed Pro Forma Financial Information (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Unaudited Condensed Pro Forma Financial Information
Total revenues	$154,484	$153,847
Net income	12,990	13,252
Net income attributable to common shareholders	$10,628	$10,890
Earnings per common share b basic and diluted:
Net income per common share attributable to common shareholders	$0.04	$0.05
Weighted average number of common shares outstanding b basic	236,250	236,151

Dispositions_Summary_of_Dispos

Dispositions - Summary of Dispositions (Details) (USD $)	3 Months Ended		0 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Jan. 20, 2015	Feb. 27, 2015	Mar. 11, 2014
Dispositions
Aggregate proceeds, net	$35,343	$9,204
Gain	4,572	655
Aon Hewitt East Campus
Dispositions
Square footage			343,000
Consideration			17,233
Aggregate proceeds, net			16,495
Gain			0
Promenade at Red Cliff
Dispositions
Square footage				94,500
Consideration				19,050
Aggregate proceeds, net				18,848
Gain				4,572
Riverpark Phase IIA
Dispositions
Square footage					64,300
Consideration					9,269
Aggregate proceeds, net					9,204
Gain					655
2015 Dispositions
Dispositions
Square footage	437,500
Consideration	36,283
Aggregate proceeds, net	35,343
Gain	$4,572

Dispositions_Assets_and_Liabil

Dispositions - Assets and Liabilities of Properties Classified as Held for Sale (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Assets
Assets associated with investment properties held for sale	$5,041	$33,640
Liabilities
Liabilities associated with investment properties held for sale	320	8,203
Investment properties held for sale
Assets
Land, building and other improvements	4,972	36,020
Accumulated depreciation	-58	-5,358
Net investment properties	4,914	30,662
Other assets	127	2,978
Assets associated with investment properties held for sale	5,041	33,640
Liabilities
Mortgage payable	0	8,075
Other liabilities	320	128
Liabilities associated with investment properties held for sale	$320	$8,203
Hartford Insurance Building | Investment properties held for sale
Investment Properties Held for Sale
Square footage	97,400

Compensation_Plans_Unvested_Re

Compensation Plans - Unvested Restricted Shares (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Unvested Restricted Shares
Balance at the end of the period (in shares)	871		414
Restricted shares
Compensation Plans
Compensation expense	$1,369		$587
Fair value of shares vested	2,613
Unvested Restricted Shares
Balance at the beginning of the period (in shares)	396
Shares granted (in shares)	637	[1]
Shares vested (in shares)	-162
Balance at the end of the period (in shares)	871
Weighted Average Grant Date Fair Value per Restricted Share
Balance at the beginning of the period (in dollars per share)	$14.26
Shares granted (in dollars per share)	$16.02
Shares vested (in dollars per share)	$14.03
Balance at the end of the period (in dollars per share)	$15.59
Compensation Cost Not Yet Recognized
Total unrecognized compensation expense	$10,919
Unrecognized compensation expense, period for recognition (in years)	1 year 6 months
Restricted shares | Minimum
Compensation Plans
Vesting period for shares granted	1 year
Restricted shares | Maximum
Compensation Plans
Vesting period for shares granted	3 years
[1]	Shares granted vest ratably over periods ranging from one to three years in accordance with the terms of applicable award documents.

Compensation_Plans_Stock_Optio

Compensation Plans - Stock Options (Details) (Stock options, USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Stock options
Independent Director Stock Option and Incentive Plan
Compensation expense		$2
Stock Options
Options granted (in shares)	84
Options exercised (in shares)	3
Options expired (in shares)	6
Options forfeited (in shares)	11

Mortgages_Payable_Summary_Deta

Mortgages Payable - Summary (Details) (USD $)	0 Months Ended				3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2015		Dec. 31, 2014
Mortgages Payable
Total debt	$2,543,080	[1]			$2,543,080	[1]
Weighted average interest rate (as a percent)	4.84%				4.84%
Number of investment properties classified as held for sale			1				1
Weighted average | Debt repaid
Mortgages Payable
Fixed interest rate (as a percent)	6.53%				6.53%
Fixed rate debt
Mortgages Payable
Total debt	2,342,858				2,342,858
Weighted average interest rate (as a percent)	5.11%				5.11%
Variable rate debt
Mortgages Payable
Total debt	200,222				200,222
Weighted average interest rate (as a percent)	1.70%				1.70%
Mortgages payable
Mortgages Payable
Variable rate debt swapped to fixed rate debt	8,070		8,124		8,070		8,124
Mortgages payable repaid and defeased					77,135
Scheduled principal payments related to amortizing loans	4,145				4,145
Mortgages payable | Fixed rate debt
Mortgages Payable
Total debt	1,542,858	[2],[3]	1,616,063	[2]	1,542,858	[2],[3]	1,616,063	[2]
Weighted average interest rate (as a percent)	6.01%		6.03%		6.01%		6.03%
Weighted average years to maturity	3 years 11 months		4 years
Mortgages payable associated with investment properties held for sale			8,075				8,075
Mortgages payable | Fixed rate debt | Minimum
Mortgages Payable
Fixed interest rate (as a percent)	3.35%		3.35%		3.35%		3.35%
Mortgages payable | Fixed rate debt | Maximum
Mortgages Payable
Fixed interest rate (as a percent)	8.00%		8.00%		8.00%		8.00%
Construction loan | Variable rate debt
Mortgages Payable
Total debt	15,222	[4]	14,900	[4]	15,222	[4]	14,900	[4]
Variable interest rate (as a percent)	2.44%		2.44%		2.44%		2.44%
Weighted average years to maturity	7 months 15 days		10 months
Variable interest rate spread (as a percent)					2.25%
Secured debt
Mortgages Payable
Total debt	1,558,080		1,630,963		1,558,080		1,630,963
Premium, net of accumulated amortization	3,218		3,972		3,218		3,972
Discount, net of accumulated amortization	-342		-470		-342		-470
Mortgages payable, net	1,560,956		1,634,465		1,560,956		1,634,465
Weighted average interest rate (as a percent)	5.97%		5.99%		5.97%		5.99%
Weighted average years to maturity	3 years 11 months		3 years 11 months
Amount of mortgage and construction loans guaranteed	8,106				8,106
IW JV 2009 LLC
Mortgages Payable
Cross-collateralized mortgage loan balance	$460,078				$460,078
Number of properties in cross-collateralized mortgage	53				53
[1]	As of MarchB 31, 2015, the weighted average years to maturity of consolidated indebtedness was 4.7 years.
[2]	Includes $8,070 and $8,124 of variable rate mortgage debt that was swapped to a fixed rate as of MarchB 31, 2015 and DecemberB 31, 2014, respectively, and excludes mortgages payable of $8,075 associated with one investment property classified as held for sale as of DecemberB 31, 2014. The fixed rate mortgages had interest rates ranging from 3.35% to 8.00% as of MarchB 31, 2015 and DecemberB 31, 2014, respectively.
[3]	Includes $8,070 of variable rate mortgage debt that was swapped to a fixed rate as of MarchB 31, 2015. Excludes mortgage premium of $3,218 and discount of $(342), net of accumulated amortization, which was outstanding as of MarchB 31, 2015.
[4]	The variable rate construction loan bears interest at a floating rate of London Interbank Offered Rate (LIBOR) plus 2.25%.

Mortgages_Payable_Scheduled_De

Mortgages Payable - Scheduled Debt Maturities (Details) (USD $)	0 Months Ended				3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2015
Debt Maturities
2015	$320,357				320,357
2016	67,703				67,703
2017	356,090				356,090
2018	462,376				462,376
2019	501,308				501,308
Thereafter	835,246				835,246
Total	2,543,080	[1]			2,543,080	[1]
Weighted average interest rate on debt (as a percent)
2015	5.25%				5.25%
2016	5.06%				5.06%
2017	5.15%				5.15%
2018	2.00%				2.00%
2019	7.50%				7.50%
Thereafter	4.51%				4.51%
Total	4.84%				4.84%
Fixed rate debt
Debt Maturities
2015	305,135				305,135
2016	67,703				67,703
2017	321,090				321,090
2018	312,376				312,376
2019	501,308				501,308
Thereafter	835,246				835,246
Total	2,342,858				2,342,858
Weighted average interest rate on debt (as a percent)
2015	5.39%				5.39%
2016	5.06%				5.06%
2017	5.53%				5.53%
2018	2.18%				2.18%
2019	7.50%				7.50%
Thereafter	4.51%				4.51%
Total	5.11%				5.11%
Variable rate debt
Debt Maturities
2015	15,222				15,222
2016	0				0
2017	35,000				35,000
2018	150,000				150,000
2019	0				0
Thereafter	0				0
Total	200,222				200,222
Weighted average interest rate on debt (as a percent)
2015	2.44%				2.44%
2016	0.00%				0.00%
2017	1.68%				1.68%
2018	1.63%				1.63%
2019	0.00%				0.00%
Thereafter	0.00%				0.00%
Total	1.70%				1.70%
Mortgages payable
Mortgages Payable
Variable rate debt swapped to fixed rate debt	8,070		8,124		8,070
Mortgages payable | Fixed rate debt
Mortgages Payable
Weighted average years to maturity	3 years 11 months		4 years
Debt Maturities
2015	305,135				305,135
2016	67,703				67,703
2017	321,090				321,090
2018	12,376				12,376
2019	501,308				501,308
Thereafter	335,246				335,246
Total	1,542,858	[2],[3]	1,616,063	[2]	1,542,858	[2],[3]
Weighted average interest rate on debt (as a percent)
Total	6.01%		6.03%		6.01%
Unsecured credit facility
Mortgages Payable
Variable rate debt swapped to fixed rate debt	300,000				300,000
Fixed interest rate (as a percent)	0.54%				0.54%
Unsecured credit facility | LIBOR
Mortgages Payable
Reference rate for variable interest rate					one-month floating rate LIBOR
Unsecured credit facility | Fixed rate debt
Debt Maturities
2015	0				0
2016	0				0
2017	0				0
2018	300,000				300,000
2019	0				0
Thereafter	0				0
Total	300,000	[4]			300,000	[4]
Unsecured credit facility | Variable rate debt
Debt Maturities
2015	0				0
2016	0				0
2017	35,000				35,000
2018	150,000				150,000
2019	0				0
Thereafter	0				0
Total	185,000				185,000
Unsecured notes payable
Mortgages Payable
Discount, net of accumulated amortization	-1,178				-1,178
Unsecured notes payable | Fixed rate debt
Debt Maturities
2015	0				0
2016	0				0
2017	0				0
2018	0				0
2019	0				0
Thereafter	500,000				500,000
Total	500,000	[5]			500,000	[5]
Construction loan | Variable rate debt
Mortgages Payable
Weighted average years to maturity	7 months 15 days		10 months
Debt Maturities
2015	15,222				15,222
2016	0				0
2017	0				0
2018	0				0
2019	0				0
Thereafter	0				0
Total	15,222	[6]	14,900	[6]	15,222	[6]
Secured debt
Mortgages Payable
Premium, net of accumulated amortization	3,218		3,972		3,218
Discount, net of accumulated amortization	-342		-470		-342
Weighted average years to maturity	3 years 11 months		3 years 11 months
Debt Maturities
Total	$1,558,080		$1,630,963		1,558,080
Weighted average interest rate on debt (as a percent)
Total	5.97%		5.99%		5.97%
Consolidated indebtedness
Mortgages Payable
Weighted average years to maturity	4 years 8 months 15 days
[1]	As of MarchB 31, 2015, the weighted average years to maturity of consolidated indebtedness was 4.7 years.
[2]	Includes $8,070 and $8,124 of variable rate mortgage debt that was swapped to a fixed rate as of MarchB 31, 2015 and DecemberB 31, 2014, respectively, and excludes mortgages payable of $8,075 associated with one investment property classified as held for sale as of DecemberB 31, 2014. The fixed rate mortgages had interest rates ranging from 3.35% to 8.00% as of MarchB 31, 2015 and DecemberB 31, 2014, respectively.
[3]	Includes $8,070 of variable rate mortgage debt that was swapped to a fixed rate as of MarchB 31, 2015. Excludes mortgage premium of $3,218 and discount of $(342), net of accumulated amortization, which was outstanding as of MarchB 31, 2015.
[4]	$300,000 of LIBOR-based variable rate debt has been swapped to a fixed rate through February 24, 2016. The swap effectively converts one-month floating rate LIBOR to a fixed rate of 0.53875% over the term of the swap.
[5]	Excludes discount of $(1,178), net of accumulated amortization, which was outstanding as of MarchB 31, 2015.
[6]	The variable rate construction loan bears interest at a floating rate of London Interbank Offered Rate (LIBOR) plus 2.25%.

Unsecured_Notes_Payable_Detail

Unsecured Notes Payable (Details) (USD $)	0 Months Ended
In Thousands, unless otherwise specified	Mar. 12, 2015	Mar. 31, 2015	Dec. 31, 2014	Jun. 30, 2014
Unsecured Notes Payable
Principal balance		$498,822	$250,000
Senior Notes
Unsecured Notes Payable
Principal balance		500,000
Weighted average interest rate (as a percent)		4.20%
Discount, net of accumulated amortization		-1,178
4.00% Senior Notes Due 2025 | Senior Notes
Unsecured Notes Payable
Principal amount	250,000
Stated interest rate (as a percent)	4.00%	4.00%
Percentage of principal amount (as a percent)	99.53%
Effective interest rate (as a percent)	4.06%
Principal balance		250,000
Series A and B Senior Notes | Senior Notes
Unsecured Notes Payable
Principal amount				250,000
4.12% Series A Senior Notes Due 2021 | Senior Notes
Unsecured Notes Payable
Principal amount				100,000
Stated interest rate (as a percent)		4.12%		4.12%
Principal balance		100,000
4.58% Series B Senior Notes Due 2024 | Senior Notes
Unsecured Notes Payable
Principal amount				150,000
Stated interest rate (as a percent)		4.58%		4.58%
Principal balance		$150,000

Unsecured_Credit_Facility_Deta

Unsecured Credit Facility (Details) (USD $)	12 Months Ended	3 Months Ended		0 Months Ended
In Thousands, unless otherwise specified	Dec. 31, 2014	Mar. 31, 2015		13-May-13
	rating_agency
Unsecured Credit Facility
Number of rating agencies	2
Balance	$0	35,000
Unsecured credit facility
Unsecured Credit Facility
Balance	450,000	485,000
Unsecured credit facility | Weighted average
Unsecured Credit Facility
Interest rate (as percent)	1.87%	1.86%
Unsecured revolving line of credit | Variable rate debt
Unsecured Credit Facility
Balance	0	35,000	[1]
Interest rate (as percent)	1.67%	1.68%
Unsecured revolving line of credit | Minimum
Unsecured Credit Facility
Quarterly unused fees (as a percent)		0.25%
Unsecured revolving line of credit | Maximum
Unsecured Credit Facility
Quarterly unused fees (as a percent)		0.30%
Unsecured revolving line of credit | LIBOR
Unsecured Credit Facility
Reference rate for variable interest rate		LIBOR
Unsecured revolving line of credit | LIBOR | Minimum
Unsecured Credit Facility
Variable interest rate spread (as a percent)		1.50%
Unsecured revolving line of credit | LIBOR | Maximum
Unsecured Credit Facility
Variable interest rate spread (as a percent)		2.05%
Unsecured revolving line of credit | Investment grade rated | Minimum
Unsecured Credit Facility
Facility fee (as a percent)		0.15%
Unsecured revolving line of credit | Investment grade rated | Maximum
Unsecured Credit Facility
Facility fee (as a percent)		0.35%
Unsecured revolving line of credit | Investment grade rated | LIBOR
Unsecured Credit Facility
Reference rate for variable interest rate		LIBOR
Unsecured revolving line of credit | Investment grade rated | LIBOR | Minimum
Unsecured Credit Facility
Variable interest rate spread (as a percent)		0.90%
Unsecured revolving line of credit | Investment grade rated | LIBOR | Maximum
Unsecured Credit Facility
Variable interest rate spread (as a percent)		1.70%
Unsecured term loan
Unsecured Credit Facility
Variable interest rate spread (as a percent)	1.45%	1.45%
Variable rate debt swapped to fixed rate debt		300,000
Fixed interest rate (as a percent)		0.54%
Unsecured term loan | Fixed rate debt
Unsecured Credit Facility
Balance	300,000	300,000	[2]
Interest rate (as percent)	1.99%	1.99%
Unsecured term loan | Variable rate debt
Unsecured Credit Facility
Balance	150,000	150,000
Interest rate (as percent)	1.62%	1.63%
Unsecured term loan | Minimum
Unsecured Credit Facility
Variable interest rate spread (as a percent)		1.45%
Unsecured term loan | Maximum
Unsecured Credit Facility
Variable interest rate spread (as a percent)		2.00%
Unsecured term loan | LIBOR
Unsecured Credit Facility
Reference rate for variable interest rate		LIBOR
Unsecured term loan | LIBOR | Minimum
Unsecured Credit Facility
Variable interest rate spread (as a percent)		1.45%
Unsecured term loan | LIBOR | Maximum
Unsecured Credit Facility
Variable interest rate spread (as a percent)		2.00%
Unsecured term loan | Investment grade rated | LIBOR
Unsecured Credit Facility
Reference rate for variable interest rate		LIBOR
Unsecured term loan | Investment grade rated | LIBOR | Minimum
Unsecured Credit Facility
Variable interest rate spread (as a percent)		1.05%
Unsecured term loan | Investment grade rated | LIBOR | Maximum
Unsecured Credit Facility
Variable interest rate spread (as a percent)		2.05%
KeyBank and Wells Fargo Syndicate | Unsecured credit facility
Unsecured Credit Facility
Aggregate borrowing capacity				1,000,000
Maximum borrowing capacity				1,450,000
KeyBank and Wells Fargo Syndicate | Unsecured revolving line of credit
Unsecured Credit Facility
Aggregate borrowing capacity				550,000
Period of extension of maturity (in years)				1 year
Extension fee as a percentage of commitment amount				0.15%
KeyBank and Wells Fargo Syndicate | Unsecured term loan
Unsecured Credit Facility
Principal amount				$450,000
[1]	The Company has a one year extension option on the unsecured revolving line of credit, which it may exercise as long as it is in compliance with the terms of the unsecured credit agreement and it pays an extension fee equal to 0.15% of the commitment amount being extended.
[2]	$300,000 of the term loan has been swapped to a fixed rate of 0.53875% plus a margin based on a leverage grid ranging from 1.45% to 2.00% through February 24, 2016. The applicable margin was 1.45% as of MarchB 31, 2015 and DecemberB 31, 2014.

Derivatives_Interest_Rate_Swap

Derivatives - Interest Rate Swaps Designated as Cash Flow Hedges (Details) (Interest rate swaps, Cash flow hedges, USD $)	0 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
		instrument	instrument
Interest rate swaps | Cash flow hedges
Derivatives
Number of interest rate swaps utilized to hedge variable cash flows	2	2	2
Amount of gain (loss) on cash flow hedges expected to be reclassified to interest expense over the next 12 months	$607
Interest Rate Derivatives
Number of instruments	2	2	2
Notional	$308,070	$308,070	$308,124

Derivatives_Estimated_Fair_Val

Derivatives - Estimated Fair Value (Details) (Interest rate swaps, Cash flow hedges, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Interest rate swaps | Cash flow hedges
Fair Value of Derivative Financial Instruments
Fair value of derivatives	$632	$562

Derivatives_Effect_on_Statemen

Derivatives - Effect on Statements of Operations (Details) (Interest rate swaps, Cash flow hedges, USD $)	3 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Interest rate swaps | Cash flow hedges
(Gain) Loss on Derivative Instruments
Amount of loss recognized in other comprehensive income on derivative (effective portion)	$386	$309
Amount of loss reclassified from AOCI into income (effective portion)	291	291
Amount of gain recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	($25)	($13)

Equity_Details

Equity (Details) (2013 ATM Equity Program, USD $)	1 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2013	Mar. 31, 2015
2013 ATM Equity Program
Equity
Maximum aggregate offering price	$200,000
Aggregate offering price of remaining common shares available for sale		$115,165

Earnings_per_Share_Details

Earnings per Share (Details) (USD $)	3 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Numerator:
Income from continuing operations	$8,504		$13,621
Gain on sales of investment properties	4,572		0
Preferred stock dividends	-2,362		-2,362
Income from continuing operations attributable to common shareholders	10,714		11,259
Income from discontinued operations	0		507
Net income attributable to common shareholders	10,714		11,766
Distributions paid on unvested restricted shares	-66		-25
Net income attributable to common shareholders excluding amounts attributable to unvested restricted shares	$10,648		$11,741
Denominator for earnings per common share b basic:
Weighted average number of common shares outstanding	236,250	[1]	236,151	[2]
Effect of dilutive securities b stock options	3	[3]	2	[3]
Denominator for earnings per common share b diluted:
Weighted average number of common and common equivalent shares outstanding	236,253		236,153
Earnings per Share
Unvested restricted common stock	871		414
Weighted average number of shares of restricted stock	611		264
Stock options
Anti-dilutive Securities Excluded from Computation of Earnings per Share
Number of outstanding options to purchase shares of common stock	64		78
Weighted average exercise price of outstanding options (in dollars per share)	$19.32		$19.10
Number of outstanding options to purchase shares of common stock that would be anti-dilutive	54		64
Weighted average exercise price of outstanding options excluded from diluted EPS calculation (in dollars per share)	$20.72		$20.71
[1]	Excludes 871 shares of unvested restricted common stock, which equate to 611 shares on a weighted average basis for the three months ended MarchB 31, 2015. These shares will continue to be excluded from the computation of basic EPS until contingencies are resolved and the shares are released.
[2]	Excludes 414 shares of unvested restricted common stock, which equate to 264 shares on a weighted average basis for the three months ended MarchB 31, 2014. These shares will continue to be excluded from the computation of basic EPS until contingencies are resolved and the shares are released.
[3]	There were outstanding options to purchase 64 and 78 shares of common stock as of MarchB 31, 2015 and 2014, respectively, at a weighted average exercise price of $19.32 and $19.10, respectively. Of these totals, outstanding options to purchase 54 and 64 shares of common stock as of MarchB 31, 2015 and 2014, respectively, at a weighted average exercise price of $20.72 and $20.71, respectively, have been excluded from the common shares used in calculating diluted earnings per share as including them would be anti-dilutive.

Provision_for_Impairment_of_In2

Provision for Impairment of Investment Properties (Details) (USD $)	3 Months Ended				0 Months Ended	1 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014		Apr. 07, 2015	5-May-15
	property		property			sqft
Provision for Impairment of Investment Properties
Number of properties with impairment indicators	6		12	[1]
Number of properties with impairment indicators for which an impairment charge was recorded			1
Number of properties held for sale with impairment indicators but not impaired	1	[2]
Number of properties with impairment indicators whose undiscounted cash flows exceeded its carrying value	5		11
Weighted average percentage in which undiscounted cash flows exceeded carrying value	66.00%		19.00%
Number of properties with impairment indicators which were subsequently sold or classified as held for sale	7
Gain on sales of investment properties	$4,572		$655
Provision for impairment of investment properties	0		394
Midtown Center
Provision for Impairment of Investment Properties
Square footage			408,500
Provision for impairment of investment properties			394
Estimated fair value of impaired property as of impairment date			47,150
Hartford Insurance Building | Subsequent events
Provision for Impairment of Investment Properties
Gain on sales of investment properties					$860	$860
Square footage						97,400
[1]	Includes seven properties which were subsequently sold or classified as held for sale as of MarchB 31, 2015.
[2]	Hartford Insurance Building was classified as held for sale as of MarchB 31, 2015. This property was not considered impaired based upon the executed sales contract and it was sold on April 7, 2015 with an anticipated gain on sale of approximately $860.

Fair_Value_Measurements_Fair_V

Fair Value Measurements - Fair Value of Financial Instruments (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Financial liabilities:
Mortgages payable, net	$1,560,956	$1,634,465
Unsecured notes payable, net	498,822	250,000
Carrying value
Financial liabilities:
Mortgages payable, net	1,560,956	1,634,465
Unsecured notes payable, net	498,822	250,000
Unsecured credit facility	485,000	450,000
Derivative liability	632	562
Fair value
Financial liabilities:
Mortgages payable, net	1,679,271	1,749,671
Unsecured notes payable, net	519,560	258,360
Unsecured credit facility	487,205	451,502
Derivative liability	$632	$562

Fair_Value_Measurements_Recurr

Fair Value Measurements - Recurring Fair Value Measurements (Details) (Recurring Fair Value Measurements, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Thousands, unless otherwise specified
Fair Value Measurements
Derivative liability	$632	$562
Fair value, Level 2
Fair Value Measurements
Derivative liability	$632	$562

Fair_Value_Measurements_Nonrec

Fair Value Measurements - Nonrecurring Fair Value Measurements (Details) (USD $)	3 Months Ended		12 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014		Sep. 30, 2014
Fair Value Measurements
Provision for impairment	$0	$394
Shaw's Supermarket
Fair Value Measurements
Fair value of investment properties			3,100
The Gateway
Fair Value Measurements
Fair value of investment properties			75,400
Hartford Insurance Building
Fair Value Measurements
Fair value of investment properties			5,000
Citizen's Property Insurance Building
Fair Value Measurements
Fair value of investment properties			3,000
Aon Hewitt East Campus
Fair Value Measurements
Transaction costs			738
Minimum
Fair Value Measurements
Operating expense growth rates					1.39%
Discount rates					8.25%
Terminal capitalization rates					7.50%
Maximum
Fair Value Measurements
Operating expense growth rates					3.70%
Discount rates					9.50%
Terminal capitalization rates					8.50%
Nonrecurring Fair Value Measurements
Fair Value Measurements
Fair value of investment properties			86,500
Fair value of investment properties held for sale			17,233
Provision for impairment			59,352
Nonrecurring Fair Value Measurements | Investment properties held for sale
Fair Value Measurements
Provision for impairment			563	[1]
Nonrecurring Fair Value Measurements | Fair value, Level 2
Fair Value Measurements
Fair value of investment properties held for sale			17,233
Nonrecurring Fair Value Measurements | Fair value, Level 3
Fair Value Measurements
Fair value of investment properties			$86,500	[2]
[1]	Represents an impairment charge recorded during the three months ended December 31, 2014 for Aon Hewitt East Campus, which was classified as held for sale as of December 31, 2014. Such charge, calculated as the expected sales price from the executed sales contract less estimated transaction costs as compared to the Companybs carrying value of its investment, was determined to be a Level 2 input. The estimated transaction costs totaling $738 are not reflected as a reduction to the fair value disclosed in the table above but were included in the calculation of the impairment charge.
[2]	Represents the fair values of the Companybs Shawbs Supermarket, The Gateway, Hartford Insurance Building and Citizenbs Property Insurance Building investment properties. The estimated fair values of Shawbs Supermarket and The Gateway of $3,100 and $75,400, respectively, were determined using the income approach. The income approach involves discounting the estimated income stream and reversion (presumed sale) value of a property over an estimated holding period to a present value at a risk-adjusted rate. Discount rates, growth assumptions and terminal capitalization rates utilized in this approach are derived from property-specific information, market transactions and other industry data. The terminal capitalization rate and discount rate are significant inputs to this valuation. The following were the key Level 3 inputs used in estimating the fair value of Shawbs Supermarket and The Gateway as of September 30, 2014. 2014 LowB HighRental growth ratesB Varies (i)B Varies (i)Operating expense growth ratesB 1.39%B 3.70%Discount ratesB 8.25%B 9.50%Terminal capitalization ratesB 7.50%B 8.50%(i) Since cash flow models are established at the tenant level, projected rental revenue growth rates fluctuate over the course of the estimated holding period based upon the timing of lease rollover, amount of available space and other property and space-specific factors.The estimated fair values of Hartford Insurance Building and Citizenbs Property Insurance Building of $5,000 and $3,000, respectively, were based upon third party comparable sales prices, which contain unobservable inputs used by these third parties to determine the estimated fair values.

Fair_Value_Measurements_Fair_V1

Fair Value Measurements - Fair Value Disclosures (Details) (USD $)	9 Months Ended	0 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2014	Mar. 31, 2015	Dec. 31, 2014	Mar. 12, 2015
Fair Value Measurements
Mortgages payable, net		1,560,956	1,634,465
Unsecured notes payable, net		498,822	250,000
Minimum
Fair Value Measurements
Discount rate (as a percent)	8.25%
Maximum
Fair Value Measurements
Discount rate (as a percent)	9.50%
Mortgages payable | Minimum
Fair Value Measurements
Discount rate (as a percent)		2.20%	2.20%
Mortgages payable | Maximum
Fair Value Measurements
Discount rate (as a percent)		5.50%	4.00%
Unsecured notes payable
Fair Value Measurements
Unsecured notes payable, net		500,000
Unsecured notes payable | 4.00% Senior Notes Due 2025
Fair Value Measurements
Unsecured notes payable, net		250,000
Stated interest rate (as a percent)		4.00%		4.00%
Unsecured notes payable | Series A and B Senior Notes | Weighted average
Fair Value Measurements
Discount rate (as a percent)		3.59%	3.97%
Unsecured term loan
Fair Value Measurements
Discount rate (as a percent)		1.30%	1.35%
Unsecured revolving line of credit
Fair Value Measurements
Discount rate (as a percent)		1.35%
Fair value, Total
Fair Value Measurements
Mortgages payable, net		1,679,271	1,749,671
Unsecured notes payable, net		519,560	258,360
Unsecured credit facility		487,205	451,502
Fair value, Level 3
Fair Value Measurements
Mortgages payable, net		1,679,271	1,749,671
Unsecured notes payable, net		267,275	258,360
Unsecured credit facility		487,205	451,502
Fair value, Level 1
Fair Value Measurements
Unsecured notes payable, net		252,285

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (Guarantees, Mortgage and construction loans, USD $)	Mar. 31, 2015
In Thousands, unless otherwise specified
Guarantees | Mortgage and construction loans
Commitments and Contingencies
Amount of mortgage and construction loans guaranteed	$8,106

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	3 Months Ended		12 Months Ended	0 Months Ended		1 Months Ended	0 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Apr. 27, 2015	Apr. 07, 2015	5-May-15	4-May-15
						sqft
Subsequent Events
Proceeds from unsecured revolving line of credit	$335,000	$101,000
Repayment of mortgage payable	71,505	50,114
Gain on sales of investment properties	4,572	655
Preferred stock dividends declared (per share)	$0.44	$0.44
Common stock dividends declared (per share)	$0.17	$0.17
7.00% Series A cumulative redeemable preferred stock
Subsequent Events
Preferred stock, dividend rate	7.00%		7.00%
Subsequent events | 7.00% Series A cumulative redeemable preferred stock
Subsequent Events
Preferred stock, dividend rate				7.00%
Preferred stock dividends declared (per share)				$0.44
Subsequent events | Class A common stock
Subsequent Events
Common stock dividends declared (per share)				$0.17
Subsequent events | Hartford Insurance Building
Subsequent Events
Square footage						97,400
Sales price						6,015
Gain on sales of investment properties					860	860
Subsequent events | Rasmussen College
Subsequent Events
Square footage						26,700
Sales price						4,800
Gain on sales of investment properties						1,334
Subsequent events | Mortgages payable
Subsequent Events
Repayment of mortgage payable						21,684
Interest rate (as a percent)						8.00%
Subsequent events | Tysons Corner
Subsequent Events
Square footage						38,000	38,000
Gross purchase price						31,556	31,556
Subsequent events | Unsecured revolving line of credit
Subsequent Events
Proceeds from unsecured revolving line of credit						$60,000