STAG Industrial (STAG) 10-Q 30 Apr 19 2019 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	Apr. 29, 2019
Document and Entity Information
Entity Registrant Name	STAG Industrial, Inc.
Entity Central Index Key	0001479094
Document Period End Date	Mar. 31, 2019
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding		125,652,464
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Rental Property:
Land	$ 377,530	$ 364,023
Buildings and improvements, net of accumulated depreciation of $321,010 and $316,930, respectively	2,392,547	2,285,663
Deferred leasing intangibles, net of accumulated amortization of $224,740 and $246,502, respectively	348,439	342,015
Total rental property, net	3,118,516	2,991,701
Cash and cash equivalents	7,857	7,968
Restricted cash	4,451	14,574
Tenant accounts receivable	44,928	42,236
Prepaid expenses and other assets	42,503	36,902
Interest rate swaps	5,214	9,151
Operating lease right-of-use assets	16,005	0
Total assets	3,239,474	3,102,532
Liabilities:
Unsecured credit facility	115,500	100,500
Unsecured term loans, net	596,642	596,360
Unsecured notes, net	572,587	572,488
Mortgage notes, net	56,109	56,560
Accounts payable, accrued expenses and other liabilities	41,381	45,507
Interest rate swaps	7,060	4,011
Tenant prepaid rent and security deposits	21,254	22,153
Dividends and distributions payable	15,846	13,754
Deferred leasing intangibles, net of accumulated amortization of $10,394 and $12,764, respectively	20,468	21,567
Operating lease liabilities	17,786	0
Total liabilities	1,464,633	1,432,900
Preferred stock, par value $0.01 per share, 15,000,000 shares authorized,
Common stock, par value $0.01 per share, 150,000,000 shares authorized, 118,174,102 and 112,165,786 shares issued and outstanding at March 31, 2019 and December 31, 2018, respectively	1,182	1,122
Additional paid-in capital	2,266,695	2,118,179
Cumulative dividends in excess of earnings	(621,225)	(584,979)
Accumulated other comprehensive income (loss)	(2,253)	4,481
Total stockholders’ equity	1,719,399	1,613,803
Noncontrolling interest	55,442	55,829
Total equity	1,774,841	1,669,632
Total liabilities and equity	3,239,474	3,102,532
Series C Preferred Stock
Preferred stock, par value $0.01 per share, 15,000,000 shares authorized,
Preferred stock	$ 75,000	$ 75,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Building and Improvements	$ 321,010	$ 316,930
Deferred leasing intangibles assets, accumulated amortization	224,740	246,502
Deferred leasing intangibles liabilities, accumulated amortization	$ 10,394	$ 12,764
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	15,000,000	15,000,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common Stock, shares, issued	112,165,786	112,165,786
Common stock, shares outstanding	112,165,786	112,165,786
Series C Preferred Stock
Preferred stock, shares issued	3,000,000	3,000,000
Preferred stock, shares outstanding	3,000,000	3,000,000
Preferred stock, liquidation preference (in dollars per share)	$ 25	$ 25

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues [Abstract]
Rental income	$ 95,615	$ 83,127
Other income	87	156
Total revenue	95,702	83,283
Expenses
Property	19,511	17,499
General and administrative	9,212	8,748
Depreciation and amortization	42,303	39,965
Loss on impairments	5,344	2,934
Other expenses	399	291
Total expenses	76,769	69,437
Other income (expense)
Interest and other income	16	6
Interest expense	(12,834)	(11,392)
Gain on the sales of rental property, net	1,274	22,689
Total other income (expense)	(11,544)	11,303
Net income	7,389	25,149
Less: income attributable to noncontrolling interest after preferred stock dividends	214	954
Net income attributable to STAG Industrial, Inc.	7,175	24,195
Less: preferred stock dividends	1,289	2,448
Less: amount allocated to participating securities	79	71
Net income attributable to common stockholders	$ 5,807	$ 21,676
Weighted average common shares outstanding — basic	114,721	97,021
Weighted average common shares outstanding — diluted	114,993	97,323
Net income per share — basic and diluted
Net income per share attributable to common stockholders — basic	$ 0.05	$ 0.22
Net income per share attributable to common stockholders — diluted	$ 0.05	$ 0.22

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 7,389	$ 25,149
Other comprehensive income (loss):
Income (loss) on interest rate swaps	(6,978)	7,723
Other comprehensive income (loss)	(6,978)	7,723
Comprehensive income	411	32,872
Income attributable to noncontrolling interest after preferred stock dividends	(214)	(954)
Other comprehensive (income) loss attributable to noncontrolling interest	244	(325)
Comprehensive income attributable to STAG Industrial, Inc.	$ 441	$ 31,593

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Cumulative Dividends in excess of Earnings	Accumulated Other Comprehensive Income (Loss)	Total Stockholders' Equity	Noncontrolling Interest - Unit holders in Operating Partnership
Balance at Dec. 31, 2017	$ 1,410,307	$ 145,000	$ 970	$ 1,725,825	$ (516,691)	$ 3,936	$ 1,359,040	$ 51,267
Balance (in shares) at Dec. 31, 2017			97,012,543
Increase (Decrease) in Stockholders' Equity
Cumulative effect on retained earnings					(258)	247	(11)	11
Offering costs	(107)			(107)			(107)
Dividends, Common Stock					36,966
Dividends							36,966
Dividends and Distributions, Net	38,779
Distribution Made to Limited Partner, Cash Distributions Declared								1,813
Non-cash compensation activity, net	706			(855)			(1,391)	2,097
Non-cash compensation activity (in shares)			71,373
Non-cash compensation activity (in excess of earnings)			$ (1)		(537)
Redemption of common units to common stock			$ 1	1,823			1,824	(1,824)
Redemption of common units to common stock (in shares)			145,672
Rebalancing of noncontrolling interest				(2,059)			(2,059)	2,059
Other comprehensive loss	7,723					7,398	7,398	325
Net income	25,149				24,195		24,195	954
Balance at Mar. 31, 2018	1,404,999	145,000	$ 972	1,724,627	(530,257)	11,581	1,351,923	53,076
Balance (in shares) at Mar. 31, 2018			97,229,588
Balance at Dec. 31, 2017	1,410,307	145,000	$ 970	1,725,825	(516,691)	3,936	1,359,040	$ 51,267
Balance (in shares) at Dec. 31, 2017			97,012,543
Increase (Decrease) in Stockholders' Equity
Redemption of common units to common stock (in shares)								0
Balance at Dec. 31, 2018	1,669,632	75,000	$ 1,122	2,118,179	(584,979)	4,481	1,613,803	$ 55,829
Balance (in shares) at Dec. 31, 2018			112,165,786
Increase (Decrease) in Stockholders' Equity
Cumulative effect on retained earnings	(214)				(214)		(214)
Proceeds from sales of common stock	150,189		$ 55	150,134			150,189
Proceeds from sales of common stock (in shares)			5,441,409
Offering costs	(1,660)			(1,660)			(1,660)
Dividends, Common Stock					42,834
Dividends							42,834
Dividends and Distributions, Net	44,380
Distribution Made to Limited Partner, Cash Distributions Declared								1,546
Non-cash compensation activity, net	863			(1,133)			(1,505)	2,368
Non-cash compensation activity (in shares)			127,836
Non-cash compensation activity (in excess of earnings)			$ (1)		(373)
Redemption of common units to common stock			$ 4	6,024			6,028	$ (6,028)
Redemption of common units to common stock (in shares)			439,071					0
Rebalancing of noncontrolling interest				(4,849)			(4,849)	$ 4,849
Other comprehensive loss	(6,978)					(6,734)	(6,734)	(244)
Net income	7,389				7,175		7,175	214
Balance at Mar. 31, 2019	$ 1,774,841	$ 75,000	$ 1,182	$ 2,266,695	$ (621,225)	$ (2,253)	$ 1,719,399	$ 55,442
Balance (in shares) at Mar. 31, 2019			118,174,102

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities:
Net income	$ 7,389	$ 25,149
Adjustment to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	42,303	39,965
Loss on impairments	5,344	2,934
Non-cash portion of interest expense	618	534
Amortization of above and below market leases, net	961	1,207
Straight-line rent adjustments, net	(2,256)	(2,781)
Dividends on forfeited equity compensation	6	7
Gain on the sales of rental property, net	(1,274)	(22,689)
Non-cash compensation expense	2,278	2,220
Change in assets and liabilities:
Tenant accounts receivable	(859)	848
Prepaid expenses and other assets	(2,686)	(5,531)
Accounts payable, accrued expenses and other liabilities	(3,775)	(2,720)
Tenant prepaid rent and security deposits	(899)	2,831
Total adjustments	39,761	16,825
Net cash provided by operating activities	47,150	41,974
Cash flows from investing activities:
Acquisitions of land and buildings and improvements	(159,969)	(67,077)
Additions of land and building and improvements	(5,058)	(6,317)
Acquisitions of other assets	1,049	0
Proceeds from sales of rental property, net	16,602	49,631
Acquisition deposits, net	(2,997)	(605)
Acquisitions of deferred leasing intangibles	(24,345)	(11,744)
Net cash used in investing activities	(176,816)	(36,112)
Cash flows from financing activities:
Proceeds from unsecured credit facility	208,000	110,000
Repayment of unsecured credit facility	(193,000)	(163,000)
Proceeds from unsecured term loans	0	75,000
Repayment of mortgage notes	(481)	(462)
Payment of loan fees and costs	0	(3)
Dividends and distributions	42,288	36,200
Proceeds from sales of common stock	150,189	0
Dividends and distributions	(1,444)	(1,524)
Offering costs	(1,544)	(88)
Net cash provided by (used in) financing activities	119,432	(16,277)
Decrease in cash and cash equivalents and restricted cash	(10,234)	(10,415)
Cash and cash equivalents and restricted cash—beginning of period	22,542	28,129
Cash and cash equivalents and restricted cash—end of period	12,308	17,714
Supplemental disclosure:
Cash paid for interest, net of capitalized interest	10,449	11,057
Supplemental schedule of non-cash investing and financing activities
Change in additions of land, building, and improvements included in accounts payable, accrued expenses, and other liabilities	(1,094)	1,908
Additions to building and other capital improvements from non-cash compensation	(14)	(4)
Change in loan fees, costs, and offering costs included in accounts payable, accrued expenses, and other liabilities	(116)	(90)
Leases cumulative effect adjustment	(214)	0
Dividends and distributions payable	$ 15,846	$ 14,460

Organization and Description of

Organization and Description of Business	3 Months Ended
	Mar. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Description of Business	Organization and Description of Business STAG Industrial, Inc. (the “Company”) is an industrial real estate operating company focused on the acquisition and operation of single-tenant, industrial properties throughout the United States. The Company was formed as a Maryland corporation and has elected to be treated and intends to continue to qualify as a real estate investment trust (“REIT”) under Sections 856 through 860 of the Internal Revenue Code of 1986, as amended. The Company is structured as an umbrella partnership REIT, commonly called an UPREIT, and owns substantially all of its assets and conducts substantially all of its business through its operating partnership, STAG Industrial Operating Partnership, L.P., a Delaware limited partnership (the “Operating Partnership”). As of March 31, 2019 and December 31, 2018 , the Company owned a 96.7% and 96.5% , respectively, common equity interest in the Operating Partnership. The Company, through its wholly owned subsidiary, is the sole general partner of the Operating Partnership. As used herein, the “Company” refers to STAG Industrial, Inc. and its consolidated subsidiaries and partnerships, including the Operating Partnership, except where context otherwise requires. As of March 31, 2019 , the Company owned 395 buildings in 38 states with approximately 78.2 million rentable square feet, consisting of 328 warehouse/distribution buildings, 58 light manufacturing buildings, and nine flex/office buildings. The Company’s buildings were approximately 95.2% leased to 359 tenants as of March 31, 2019 .

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Interim Financial Information The accompanying interim financial statements have been presented in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and with the instructions to Form 10-Q and Regulation S-X for interim financial information. Accordingly, these statements do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, the accompanying interim financial statements include all adjustments, consisting of normal recurring items, necessary for their fair statement in conformity with GAAP. Interim results are not necessarily indicative of results for a full year. The year-end consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the Company’s consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018 . Basis of Presentation The Company’s consolidated financial statements include the accounts of the Company, the Operating Partnership, and their subsidiaries. Interests in the Operating Partnership not owned by the Company are referred to as “Noncontrolling Common Units.” These Noncontrolling Common Units are held by other limited partners in the form of common units (“Other Common Units”) and long term incentive plan units (“LTIP units”) issued pursuant to the STAG Industrial, Inc. 2011 Equity Incentive Plan, as amended and restated (the “2011 Plan”). All significant intercompany balances and transactions have been eliminated in the consolidation of entities. The financial statements of the Company are presented on a consolidated basis for all periods presented. New Accounting Standards and Reclassifications New Accounting Standards Adopted In July 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-11 which amends Topic 842, Leases , and provides lessors with a practical expedient, by class of underlying asset, to not separate non-lease components from the associated lease component and, instead, to account for those components as a single component if the non-lease components otherwise would be accounted for under the new revenue guidance and both of the following are met: i) the timing and pattern of transfer of the non-lease component(s) and associated lease component are the same; and ii) the lease component, if accounted for separately, would be classified as an operating lease. Under this new expedient, if the non-lease components associated with the lease component are the predominant component of the combined component, a company should account for the combined component in accordance with Topic 606, Revenue from Contracts with Customers . Otherwise, the company should account for the combined component as an operating lease in accordance with Topic 842. In December 2018, the FASB issued ASU 2018-20 which amends Topic 842, Leases , and allows lessors to continue to exclude from revenue the lessor costs that are paid by lessees directly to third parties. The Company adopted Topic 842 on January 1, 2019, using the practical expedient, and it did not have a material impact on the Company’s consolidated financial statements. The Company determined that for all leases where the Company is the lessor, that the timing and pattern of transfer of the non-lease components and associated lease components are the same, and that the lease components, if accounted for separately, would be classified as an operating lease. Accordingly, the Company has made an accounting policy election to recognize the combined component in accordance with Topic 842 as rental income on the accompanying Consolidated Statements of Operations. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , and various subsequent ASU’s, which set out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessees and lessors). Topic 842 superseded the previous leases standard, Topic 840, Leases . The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification determines whether lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less are accounted for similar to the previous guidance for operating leases. The new standard requires lessors to account for leases using an approach that is substantially equivalent to the previous guidance for sales-type leases, direct financing leases and operating leases. ASU 2016-02 impacted the Company’s consolidated financial statements as the Company has ground leases and its corporate office lease for which it is the lessee, which resulted in the recording of a right-of-use asset and the related lease liability. The Company adopted ASU 2016-02 on January 1, 2019, using the modified retrospective transition method. The adoption of this standard resulted in a cumulative effect adjustment of approximately $0.2 million recorded as an increase to cumulative dividends in excess of earnings as of January 1, 2019 in the accompanying Consolidated Statements of Equity. The cumulative effect adjustment related to initial direct costs of leases where the Company is the lessor and that, as of January 1, 2019, had not begun to amortize and are no longer allowed to be capitalized under the new standard. On January 1, 2019, the Company recognized operating lease right-of-use assets of approximately $16.3 million and related operating lease liabilities of approximately $18.0 million on the accompanying Consolidated Balance Sheets, related to the leases where the Company is the lessee. The Company adopted the new standard using the practical expedient package which allowed the Company to (i) not reassess whether any expired or existing contracts are or contain leases; (ii) not reassess the lease classification for any expired or existing leases; and (iii) not reassess initial direct costs for any existing leases. This practical expedient allows the Company to continue to account for its ground leases as operating leases. Prospectively, any new or modified ground leases may be classified as a financing lease. The adoption of this standard by the Company has been applied prospectively, and the comparative periods have not been restated. For leases in which the Company is the lessee, the Company recognizes a right-of-use asset and corresponding lease liability on the accompanying Consolidated Balance Sheets equal to the present value of the fixed lease payments. In determining operating right-of-use asset and lease liability for the Company’s existing operating leases upon the adoption of the new lease guidance, the Company was required to estimate an appropriate incremental borrowing rate on a fully-collateralized basis for the terms of the leases. The Company utilized a market-based approach to estimate the incremental borrowing rate for each individual lease. Since the terms under the ground leases are significantly longer than the terms of borrowings available to the Company on a fully-collateralized basis, the estimate of this rate required significant judgment, and considered factors such as yields on outstanding public debt and other market based pricing on longer duration financing instruments. The new leases standard requires the Company to evaluate cash basis versus accrual basis of rental income recognition based on the collectability of future lease payments. Reclassifications Prior period amounts have been reclassified to conform to the current year presentation due to the adoption of ASU 2016-02. Amounts previously classified as rental income and tenant recoveries in the prior period are now classified as rental income on the accompanying Consolidated Statements of Operations, as the Company has made an accounting policy election to combine these amounts that are accounted for under the new leases standard. Restricted Cash The following table presents a reconciliation of cash and cash equivalents and restricted cash reported on the accompanying Consolidated Balance Sheets to amounts reported on the accompanying Consolidated Statements of Cash Flows. Reconciliation of cash and cash equivalents and restricted cash (in thousands) March 31, 2019 December 31, 2018 Cash and cash equivalents $ 7,857 $ 7,968 Restricted cash 4,451 14,574 Total cash and cash equivalents and restricted cash $ 12,308 $ 22,542 Taxes Federal Income Taxes The Company’s taxable REIT subsidiaries recognized a net loss of approximately $12,000 and $36,000 for the three months ended March 31, 2019 and 2018 , respectively, which has been included on the accompanying Consolidated Statements of Operations. State and Local Income, Excise, and Franchise Tax State and local income, excise, and franchise taxes in the amount of $0.2 million and $0.2 million have been recorded in other expenses on the accompanying Consolidated Statements of Operations for the three months ended March 31, 2019 and 2018 , respectively. Uncertain Tax Positions As of March 31, 2019 and December 31, 2018 , there were no liabilities for uncertain tax positions. Concentrations of Credit Risk Management believes the current credit risk of the Company’s portfolio is reasonably well diversified and does not contain any unusual concentration of credit risk.

Rental Property

Rental Property	3 Months Ended
	Mar. 31, 2019
Real Estate [Abstract]
Rental Property	Rental Property The following table summarizes the components of rental property as of March 31, 2019 and December 31, 2018 . Rental Property (in thousands) March 31, 2019 December 31, 2018 Land $ 377,530 $ 364,023 Buildings, net of accumulated depreciation of $211,755 and $199,497, respectivel y 2,180,636 2,082,781 Tenant improvements, net of accumulated depreciation of $21,026 and $36,450, respectively 31,108 30,704 Building and land improvements, net of accumulated depreciation of $88,229 and $80,983, respectivel y 173,715 168,229 Construction in progress 7,088 3,949 Deferred leasing intangibles, net of accumulated amortization of $224,740 and $246,502, respectively 348,439 342,015 Total rental property, net $ 3,118,516 $ 2,991,701 Acquisitions The following table summarizes the acquisitions of the Company during the three months ended March 31, 2019 . Market (1) Date Acquired Square Feet Buildings Purchase Price Cincinnati/Dayton, OH January 24, 2019 176,000 1 $ 9,965 Pittsburgh, PA February 21, 2019 455,000 1 28,676 Boston, MA February 21, 2019 349,870 1 26,483 Minneapolis/St Paul, MN February 28, 2019 248,816 1 21,955 Greenville/Spartanburg, SC March 7, 2019 331,845 1 24,536 Philadelphia, PA March 7, 2019 148,300 1 10,546 Omaha/Council Bluffs, NE-IA March 11, 2019 237,632 1 20,005 Houston, TX March 28, 2019 132,000 1 17,307 Baltimore, MD March 28, 2019 167,410 1 13,648 Houston, TX March 28, 2019 116,750 1 12,242 Three months ended March 31, 2019 2,363,623 10 $ 185,363 (1) As defined by CoStar Realty Information Inc (“CoStar”). If the building is located outside of a CoStar defined market, the city and state is reflected. The following table summarizes the allocation of the consideration paid at the date of acquisition during the three months ended March 31, 2019 for the acquired assets and liabilities in connection with the acquisitions identified in the table above. Acquired Assets and Liabilities Purchase Price (in thousands) Weighted Average Amortization Period (years) of Intangibles at Acquisition Land $ 18,152 N/A Buildings 127,201 N/A Tenant improvements 1,349 N/A Building and land improvements 11,235 N/A Construction in progress 2,032 N/A Other assets 1,049 N/A Deferred leasing intangibles - In-place leases 16,743 7.9 Deferred leasing intangibles - Tenant relationships 8,404 11.3 Deferred leasing intangibles - Above market leases 327 4.3 Deferred leasing intangibles - Below market leases (1,129 ) 8.5 Total purchase price $ 185,363 The table below sets forth the results of operations for the three months ended March 31, 2019 for the buildings acquired during the three months ended March 31, 2019 included in the Company’s Consolidated Statements of Operations from the date of acquisition. Results of Operations (in thousands) Three months ended March 31, 2019 Total revenue $ 1,194 Net loss $ 145 Dispositions During the three months ended March 31, 2019 , the Company sold five buildings comprised of approximately 1.0 million square feet with a net book value of approximately $15.3 million to third parties. These buildings contributed approximately $0.1 million and $1.1 million to revenue for the three months ended March 31, 2019 and 2018 , respectively. These buildings contributed approximately $(0.2) million and $0.5 million to net income (loss) (exclusive of gain on the sales of rental property, net) for the three months ended March 31, 2019 and 2018 , respectively. Net proceeds from the sales of rental property were approximately $16.6 million and the Company recognized the full gain on the sales of rental property, net, of approximately $1.3 million for the three months ended March 31, 2019 . Loss on Impairments The following table summarizes the Company's loss on impairments for assets held and used during the three months ended March 31, 2019 . Market (1) Buildings Event or Change in Circumstance Leading to Impairment Evaluation (2) Valuation technique utilized to estimate fair value Fair Value (3) Loss on Impairments (in thousands) Rapid City, SD 1 Change in estimated hold period Discounted cash flows (4) Three months ended March 31, 2019 $ 4,373 $ 5,344 (1) As defined by CoStar. If the building is located outside of a CoStar defined market, the city and state is reflected. (2) The Company tested the asset group for impairment utilizing a probability weighted recovery analysis of certain scenarios, and it was determined that the carrying value of the property and intangibles were not recoverable from the estimated future undiscounted cash flows. (3) The estimated fair value of the property is based on Level 3 inputs and is a non-recurring fair value measurement. Level 3 is defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. (4) Level 3 inputs used to determine fair value for the property impaired for the three months ended March 31, 2019 : discount rate of 12.0% and exit capitalization rate of 12.0% . Deferred Leasing Intangibles The following table sets forth the deferred leasing intangibles on the accompanying Consolidated Balance Sheets as of March 31, 2019 and December 31, 2018 . March 31, 2019 December 31, 2018 Deferred Leasing Intangibles (in thousands) Gross Accumulated Amortization Net Gross Accumulated Amortization Net Above market leases $ 70,961 $ (30,409 ) $ 40,552 $ 73,122 $ (31,059 ) $ 42,063 Other intangible lease assets 502,218 (194,331 ) 307,887 515,395 (215,443 ) 299,952 Total deferred leasing intangible assets $ 573,179 $ (224,740 ) $ 348,439 $ 588,517 $ (246,502 ) $ 342,015 Below market leases $ 30,862 $ (10,394 ) $ 20,468 $ 34,331 $ (12,764 ) $ 21,567 Total deferred leasing intangible liabilities $ 30,862 $ (10,394 ) $ 20,468 $ 34,331 $ (12,764 ) $ 21,567 The following table sets forth the amortization expense and the net decrease to rental income for the amortization of deferred leasing intangibles during the three months ended March 31, 2019 and 2018 . Three months ended March 31, Deferred Leasing Intangibles Amortization (in thousands) 2019 2018 Net decrease to rental income related to above and below market lease amortization $ 967 $ 1,207 Amortization expense related to other intangible lease assets $ 16,814 $ 18,100 The following table sets forth the amortization of deferred leasing intangibles over the next five calendar years beginning with 2019 as of March 31, 2019 . Year Amortization Expense Related to Other Intangible Lease Assets (in thousands) Net Decrease to Rental Income Related to Above and Below Market Lease Amortization (in thousands) Remainder of 2019 $ 48,278 $ 2,900 2020 $ 54,265 $ 3,546 2021 $ 43,369 $ 2,221 2022 $ 35,017 $ 1,361 2023 $ 28,732 $ 1,363

Debt

Debt	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Debt	Debt The following table sets forth a summary of the Company’s outstanding indebtedness, including borrowings under the Company’s unsecured credit facility, unsecured term loans, unsecured notes, and mortgage notes as of March 31, 2019 and December 31, 2018 . Loan Principal Outstanding as of March 31, 2019 (in thousands) Principal Outstanding as of December 31, 2018 (in thousands) Interest (1)(2) Maturity Date Prepayment Terms (3) Unsecured credit facility: Unsecured Credit Facility (4) $ 115,500 $ 100,500 L + 0.90% Jan-15-2023 i Total unsecured credit facility 115,500 100,500 Unsecured term loans: Unsecured Term Loan C 150,000 150,000 2.39 % Sep-29-2020 i Unsecured Term Loan B 150,000 150,000 3.05 % Mar-21-2021 i Unsecured Term Loan A 150,000 150,000 2.70 % Mar-31-2022 i Unsecured Term Loan D 150,000 150,000 2.85 % Jan-04-2023 i Unsecured Term Loan E (5) — — 3.92 % Jan-15-2024 i Total unsecured term loans 600,000 600,000 Less: Total unamortized deferred financing fees and debt issuance costs (3,358 ) (3,640 ) Total carrying value unsecured term loans, net 596,642 596,360 Unsecured notes: Series F Unsecured Notes 100,000 100,000 3.98 % Jan-05-2023 ii Series A Unsecured Notes 50,000 50,000 4.98 % Oct-1-2024 ii Series D Unsecured Notes 100,000 100,000 4.32 % Feb-20-2025 ii Series G Unsecured Notes 75,000 75,000 4.10 % Jun-13-2025 ii Series B Unsecured Notes 50,000 50,000 4.98 % Jul-1-2026 ii Series C Unsecured Notes 80,000 80,000 4.42 % Dec-30-2026 ii Series E Unsecured Notes 20,000 20,000 4.42 % Feb-20-2027 ii Series H Unsecured Notes 100,000 100,000 4.27 % Jun-13-2028 ii Total unsecured notes 575,000 575,000 Less: Total unamortized deferred financing fees and debt issuance costs (2,413 ) (2,512 ) Total carrying value unsecured notes, net 572,587 572,488 Mortgage notes (secured debt): Wells Fargo Bank, National Association CMBS Loan 52,763 53,216 4.31 % Dec-1-2022 iii Thrivent Financial for Lutherans 3,767 3,795 4.78 % Dec-15-2023 iv Total mortgage notes 56,530 57,011 Add: Total unamortized fair market value premiums 48 50 Less: Total unamortized deferred financing fees and debt issuance costs (469 ) (501 ) Total carrying value mortgage notes, net 56,109 56,560 Total / weighted average interest rate (6) $ 1,340,838 $ 1,325,908 3.56 % (1) Interest rate as of March 31, 2019 . At March 31, 2019 , the one-month LIBOR (“L”) was 2.49450% . The current interest rate is not adjusted to include the amortization of deferred financing fees or debt issuance costs incurred in obtaining debt or any unamortized fair market value premiums. The spread over the applicable rate for the Company’s unsecured credit facility and unsecured term loans is based on the Company’s debt rating, as defined in the respective loan agreements. (2) As of March 31, 2019 , one-month LIBOR for the unsecured term loans A, B, C, D, and E was swapped to a fixed rate of 1.70% , 2.05% , 1.39% , 1.85% , and 2.92% , respectively. (3) Prepayment terms consist of (i) pre-payable with no penalty; (ii) pre-payable with penalty; (iii) pre-payable without penalty three months prior to the maturity date, however can be defeased; and (iv) pre-payable without penalty three months prior to the maturity date. (4) The capacity of the unsecured credit facility is $500.0 million . Deferred financing fees and debt issuance costs, net of accumulated amortization related to the unsecured credit facility of approximately $3.0 million and $3.2 million is included in prepaid expenses and other assets on the accompanying Consolidated Balance Sheets as of March 31, 2019 and December 31, 2018 , respectively. (5) Capacity of $175.0 million , which the Company has until July 25, 2019 to draw. (6) The weighted average interest rate was calculated using the fixed interest rate swapped on the notional amount of $600.0 million of debt, and is not adjusted to include the amortization of deferred financing fees or debt issuance costs incurred in obtaining debt or any unamortized fair market value premiums. The aggregate undrawn nominal commitment on the unsecured credit facility and unsecured term loans as of March 31, 2019 was approximately $553.9 million , including issued letters of credit. The Company’s actual borrowing capacity at any given point in time may be less and is restricted to a maximum amount based on the Company’s debt covenant compliance. Total accrued interest for the Company’s indebtedness was approximately $7.7 million and $5.9 million as of March 31, 2019 and December 31, 2018 , respectively, and is included in accounts payable, accrued expenses and other liabilities on the accompanying Consolidated Balance Sheets. The table below sets forth the costs included in interest expense related to the Company’s debt arrangements on the accompanying Consolidated Statement of Operations for the three months ended March 31, 2019 and 2018 . Three months ended March 31, Costs Included in Interest Expense (in thousands) 2019 2018 Amortization of deferred financing fees and debt issuance costs and fair market value premiums $ 618 $ 534 Facility, unused, and other fees $ 383 $ 339 Financial Covenant Considerations The Company was in compliance with all financial and other covenants as of March 31, 2019 and December 31, 2018 related to its unsecured credit facility, unsecured term loans, unsecured notes, and mortgage notes. The real estate net book value of the properties that are collateral for the Company’s debt arrangements was approximately $87.2 million and $88.2 million at March 31, 2019 and December 31, 2018 , respectively, and is limited to senior, property-level secured debt financing arrangements. Fair Value of Debt The following table presents the aggregate principal outstanding under the Company’s debt arrangements and the corresponding estimate of fair value as of March 31, 2019 and December 31, 2018 (in thousands). March 31, 2019 December 31, 2018 Principal Outstanding Fair Value Principal Outstanding Fair Value Unsecured credit facility $ 115,500 $ 115,500 $ 100,500 $ 100,500 Unsecured term loans 600,000 600,000 600,000 600,000 Unsecured notes 575,000 596,833 575,000 585,292 Mortgage notes 56,530 57,494 57,011 57,289 Total principal amount 1,347,030 $ 1,369,827 1,332,511 $ 1,343,081 Add: Total unamortized fair market value premiums 48 50 Less: Total unamortized deferred financing fees and debt issuance costs (6,240 ) (6,653 ) Total carrying value $ 1,340,838 $ 1,325,908 The applicable fair value guidance establishes a three tier value hierarchy, which prioritizes the inputs used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. The fair value of the Company’s debt is based on Level 3 inputs.

Use of Derivative Financial Ins

Use of Derivative Financial Instruments	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Use of Derivative Financial Instruments	Use of Derivative Financial Instruments Risk Management Objective of Using Derivatives The Company’s use of derivative instruments is limited to the utilization of interest rate swaps to manage interest rate risk exposure on existing and future liabilities and not for speculative purposes. The principal objective of such arrangements is to minimize the risks and related costs associated with the Company’s operating and financial structure. The following table details the Company’s outstanding interest rate swaps as of March 31, 2019 . All of the Company’s interest rate swaps are designated as qualifying cash flow hedges. Interest Rate Trade Date Effective Date Notional Amount Fair Value Pay Fixed Interest Rate Receive Variable Interest Rate Maturity Date Regions Bank Mar-01-2013 Mar-01-2013 $ 25,000 $ 235 1.3300 % One-month L Feb-14-2020 Capital One, N.A. Jun-13-2013 Jul-01-2013 $ 50,000 $ 316 1.6810 % One-month L Feb-14-2020 Capital One, N.A. Jun-13-2013 Aug-01-2013 $ 25,000 $ 153 1.7030 % One-month L Feb-14-2020 Regions Bank Sep-30-2013 Feb-03-2014 $ 25,000 $ 90 1.9925 % One-month L Feb-14-2020 The Toronto-Dominion Bank Oct-14-2015 Sep-29-2016 $ 25,000 $ 342 1.3830 % One-month L Sep-29-2020 PNC Bank, N.A. Oct-14-2015 Sep-29-2016 $ 50,000 $ 678 1.3906 % One-month L Sep-29-2020 Regions Bank Oct-14-2015 Sep-29-2016 $ 35,000 $ 477 1.3858 % One-month L Sep-29-2020 U.S. Bank, N.A. Oct-14-2015 Sep-29-2016 $ 25,000 $ 338 1.3950 % One-month L Sep-29-2020 Capital One, N.A. Oct-14-2015 Sep-29-2016 $ 15,000 $ 202 1.3950 % One-month L Sep-29-2020 Royal Bank of Canada Jan-08-2015 Mar-20-2015 $ 25,000 $ 256 1.7090 % One-month L Mar-21-2021 The Toronto-Dominion Bank Jan-08-2015 Mar-20-2015 $ 25,000 $ 255 1.7105 % One-month L Mar-21-2021 The Toronto-Dominion Bank Jan-08-2015 Sep-10-2017 $ 100,000 $ 18 2.2255 % One-month L Mar-21-2021 Wells Fargo, N.A. Jan-08-2015 Mar-20-2015 $ 25,000 $ 243 1.8280 % One-month L Mar-31-2022 The Toronto-Dominion Bank Jan-08-2015 Feb-14-2020 $ 25,000 $ (204 ) 2.4535 % One-month L Mar-31-2022 Regions Bank Jan-08-2015 Feb-14-2020 $ 50,000 $ (430 ) 2.4750 % One-month L Mar-31-2022 Capital One, N.A. Jan-08-2015 Feb-14-2020 $ 50,000 $ (487 ) 2.5300 % One-month L Mar-31-2022 The Toronto-Dominion Bank Jul-20-2017 Oct-30-2017 $ 25,000 $ 269 1.8485 % One-month L Jan-04-2023 Royal Bank of Canada Jul-20-2017 Oct-30-2017 $ 25,000 $ 267 1.8505 % One-month L Jan-04-2023 Wells Fargo, N.A. Jul-20-2017 Oct-30-2017 $ 25,000 $ 267 1.8505 % One-month L Jan-04-2023 PNC Bank, N.A. Jul-20-2017 Oct-30-2017 $ 25,000 $ 269 1.8485 % One-month L Jan-04-2023 PNC Bank, N.A. Jul-20-2017 Oct-30-2017 $ 50,000 $ 539 1.8475 % One-month L Jan-04-2023 The Toronto-Dominion Bank Jul-24-2018 Jul-26-2019 $ 50,000 $ (1,696 ) 2.9180 % One-month L Jan-12-2024 PNC Bank, N.A. Jul-24-2018 Jul-26-2019 $ 50,000 $ (1,699 ) 2.9190 % One-month L Jan-12-2024 Bank of Montreal Jul-24-2018 Jul-26-2019 $ 50,000 $ (1,696 ) 2.9190 % One-month L Jan-12-2024 U.S. Bank, N.A. Jul-24-2018 Jul-26-2019 $ 25,000 $ (848 ) 2.9190 % One-month L Jan-12-2024 The fair value of the interest rate swaps outstanding as of March 31, 2019 and December 31, 2018 was as follows. Balance Sheet Line Item (in thousands) Notional Amount March 31, 2019 Fair Value Notional Amount December 31, 2018 Fair Value December 31, 2018 Interest rate swaps-Asset $ 600,000 $ 5,214 $ 600,000 $ 9,151 Interest rate swaps-Liability $ 300,000 $ (7,060 ) $ 300,000 $ (4,011 ) Cash Flow Hedges of Interest Rate Risk The Company’s objectives in using interest rate swaps are to add stability to interest expense and to manage its exposure to interest rate movements. For derivatives designated and that qualify as cash flow hedges of interest rate risk, the gain or loss on the derivative is recorded in accumulated other comprehensive income (loss) and subsequently reclassified into interest expense in the same periods during which the hedged transaction affects earnings. Amounts reported in accumulated other comprehensive income (loss) related to derivatives designated as qualifying cash flow hedges will be reclassified to interest expense as interest payments are made on the Company’s variable rate debt. The Company estimates that approximately $3.0 million will be reclassified from accumulated other comprehensive income (loss) as a decrease to interest expense over the next 12 months. The table below presents the effect of cash flow hedge accounting and the location in the consolidated financial statements for the three months ended March 31, 2019 and 2018 . Three months ended March 31, Effect of Cash Flow Hedge Accounting (in thousands) 2019 2018 Income (loss) recognized in accumulated other comprehensive income (loss) on interest rate swaps $ (5,856 ) $ 7,493 Income (loss) reclassified from accumulated other comprehensive income into income (loss) as interest expense $ 1,122 $ (230 ) Total interest expense presented in the Consolidated Statements of Operations in which the effects of cash flow hedges are recorded $ 12,834 $ 11,392 Credit-risk-related Contingent Features The Company has agreements with each of its derivative counterparties that contain a provision where the Company could be declared in default on its derivative obligations if repayment of the underlying indebtedness is accelerated by the lender due to the Company’s default on the indebtedness. As of March 31, 2019 , derivatives that were in a net liability position by counterparty and subject to credit-risk-related contingent features had a termination value of approximately $3.5 million , which includes accrued interest but excludes any adjustment for nonperformance risk. As of March 31, 2019 , the Company had not breached the provisions of these agreements and had not posted any collateral related to these agreements. If the Company had breached any of these provisions at March 31, 2019 , it could have been required to settle its obligations under the agreement of the interest rate swaps in a liability position plus accrued interest for approximately $3.5 million . Fair Value of Interest Rate Swaps The Company’s valuation of the interest rate swaps is determined using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative. This analysis reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs including interest rate curves. The Company incorporates credit valuation adjustments to appropriately reflect both its own nonperformance risk and the respective counterparty’s nonperformance risk in the fair value measurements. In adjusting the fair value of its derivative contracts for the effect of nonperformance risk, the Company has considered the impact of netting and any applicable credit enhancements, such as collateral postings, thresholds, mutual puts, and guarantees. 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, 2019 and December 31, 2018 , 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 of its derivatives. As a result, the Company has determined that its derivative valuations in their entirety are classified in Level 2 of the fair value hierarchy. The following sets forth the Company’s financial instruments that are accounted for at fair value on a recurring basis as of March 31, 2019 and December 31, 2018 . Fair Value Measurements as of Balance Sheet Line Item (in thousands) Fair Value Level 1 Level 2 Level 3 Interest rate swaps-Asset $ 5,214 $ — $ 5,214 $ — Interest rate swaps-Liability $ (7,060 ) $ — $ (7,060 ) $ — Fair Value Measurements as of Balance Sheet Line Item (in thousands) Fair Value December 31, 2018 Level 1 Level 2 Level 3 Interest rate swaps-Asset $ 9,151 $ — $ 9,151 $ — Interest rate swaps-Liability $ (4,011 ) $ — $ (4,011 ) $ —

Equity

Equity	3 Months Ended
	Mar. 31, 2019
Stockholders' Equity Note [Abstract]
Equity	Equity Preferred Stock The table below sets forth the Company’s outstanding preferred stock issuances as of March 31, 2019 . Preferred Stock Issuances Issuance Date Number of Shares Liquidation Value Per Share Interest Rate 6.875% Series C Cumulative Redeemable Preferred Stock ("Series C Preferred Stock") March 17, 2016 3,000,000 $ 25.00 6.875 % The tables below set forth the dividends attributable to the Company’s outstanding preferred stock issuances during the three months ended March 31, 2019 and the year ended December 31, 2018 . Quarter Ended 2019 Declaration Date Series C Payment Date March 31 January 10, 2019 $ 0.4296875 April 1, 2019 Total $ 0.4296875 Quarter Ended 2018 Declaration Date Series B Series C Payment Date December 31 October 10, 2018 $ — $ 0.4296875 December 31, 2018 September 30 July 11, 2018 0.0460069 (1) 0.4296875 October 1, 2018 June 30 April 10, 2018 0.4140625 0.4296875 July 2, 2018 March 31 February 14, 2018 0.4140625 0.4296875 April 2, 2018 Total $ 0.8741319 $ 1.7187500 (1) On June 11, 2018, the Company gave notice to redeem all 2,800,000 issued and outstanding shares of the 6.625% Series B Cumulative Redeemable Preferred Stock (“Series B Preferred Stock”). On July 11, 2018, the Company redeemed all of the Series B Preferred Stock at a cash redemption price of $25.00 per share, plus accrued and unpaid dividends to but excluding the redemption date, without interest. On April 9, 2019 , the Company’s board of directors declared the Series C Preferred Stock dividends for the quarter ending June 30, 2019 at a quarterly rate of $0.4296875 per share. Common Stock The following table sets forth the terms of the Company’s at-the market (“ATM”) common stock offering program as of March 31, 2019 . ATM Common Stock Offering Program Date Maximum Aggregate Offering Price (in thousands) Aggregate Common Stock Available as of 2019 $600 million ATM February 14, 2019 $ 600,000 $ 449,811 The tables below set forth the activity under the ATM common stock offering programs during the three months ended March 31, 2019 and year ended December 31, 2018 (in thousands, except share data). Three months ended March 31, 2019 ATM Common Stock Offering Program Shares Weighted Average Price Per Share Gross Sales Net 2019 $600 million ATM 5,441,409 $ 27.60 $ 150,189 $ 1,302 $ 148,887 Total/weighted average 5,441,409 $ 27.60 $ 150,189 $ 1,302 $ 148,887 Year ended December 31, 2018 ATM Common Stock Offering Program Shares Weighted Average Price Per Share Gross Sales Net 2017 $500 million ATM (1) 14,724,614 $ 26.52 $ 390,447 $ 4,040 $ 386,407 Total/weighted average 14,724,614 $ 26.52 $ 390,447 $ 4,040 $ 386,407 (1) This program ended before March 31, 2019 . The tables below sets forth the dividends attributable to the Company’s outstanding shares of common stock that were declared during the three months ended March 31, 2019 and the year ended December 31, 2018 . Month Ended 2019 Declaration Date Record Date Per Share Payment Date March 31 January 10, 2019 March 29, 2019 $ 0.119167 April 15, 2019 February 28 January 10, 2019 February 28, 2019 0.119167 March 15, 2019 January 31 January 10, 2019 January 31, 2019 0.119167 February 15, 2019 Total $ 0.357501 Month Ended 2018 Declaration Date Record Date Per Share Payment Date December 31 October 10, 2018 December 31, 2018 $ 0.118333 January 15, 2019 November 30 October 10, 2018 November 30, 2018 0.118333 December 17, 2018 October 31 October 10, 2018 October 31, 2018 0.118333 November 15, 2018 September 30 July 11, 2018 September 28, 2018 0.118333 October 15, 2018 August 31 July 11, 2018 August 31, 2018 0.118333 September 17, 2018 July 31 July 11, 2018 July 31, 2018 0.118333 August 15, 2018 June 30 April 10, 2018 June 29, 2018 0.118333 July 16, 2018 May 31 April 10, 2018 May 31, 2018 0.118333 June 15, 2018 April 30 April 10, 2018 April 30, 2018 0.118333 May 15, 2018 March 31 November 2, 2017 March 29, 2018 0.118333 April 16, 2018 February 28 November 2, 2017 February 28, 2018 0.118333 March 15, 2018 January 31 November 2, 2017 January 31, 2018 0.118333 February 15, 2018 Total $ 1.419996 On April 9, 2019 , the Company’s board of directors declared the common stock dividends for the months ending April 30, 2019 , May 31, 2019 and June 30, 2019 at a monthly rate of $0.119167 per share of common stock. Restricted Shares of Common Stock Restricted shares of common stock granted on January 7, 2019 to certain employees of the Company, subject to the recipient’s continued employment, will vest in four equal installments on January 1 of each year beginning in 2020. Refer to Note 8 for a discussion of the restricted shares of common stock granted on January 7, 2019 pursuant to the March 8, 2016 performance units. The following table summarizes activity related to the Company’s unvested restricted shares of common stock for the three months ended March 31, 2019 and the year ended December 31, 2018 . Unvested Restricted Shares of Common Stock Shares Balance at December 31, 2017 237,207 Granted 76,659 (1) Vested (112,405 ) (2) Forfeited (10,999 ) Balance at December 31, 2018 190,462 Granted 110,830 (1) Vested (78,431 ) (2) Forfeited (2,320 ) Balance at March 31, 2019 220,541 (1) The fair value per share on the grant date of January 7, 2019 and January 5, 2018 was $24.85 and $26.40 , respectively. (2) The Company repurchased and retired 58,697 and 41,975 restricted shares of common stock that vested during the three months ended March 31, 2019 and the year ended December 31, 2018 , respectively. The unrecognized compensation expense associated with the Company’s restricted shares of common stock at March 31, 2019 was approximately $4.4 million and is expected to be recognized over a weighted average period of approximately 2.9 years . The following table summarizes the fair value at vesting for the restricted shares of common stock that vested during the three months ended March 31, 2019 and 2018 . Three months ended March 31, Vested Restricted Shares of Common Stock 2019 2018 Vested restricted shares of common stock 78,431 112,405 Fair value of vested restricted shares of common stock (in thousands) $ 1,951 $ 3,002

Noncontrolling Interest

Noncontrolling Interest	3 Months Ended
	Mar. 31, 2019
Noncontrolling Interest [Abstract]
Noncontrolling Interest	Noncontrolling Interest The table below summarizes the activity for noncontrolling interest in the Company for the three months ended March 31, 2019 and the year ended December 31, 2018 . Noncontrolling Interest LTIP Units Other Common Units Total Noncontrolling Common Units Noncontrolling Interest Balance at December 31, 2017 1,457,070 2,639,617 4,096,687 4.1 % Granted/Issued 324,802 — 324,802 N/A Forfeited — — — N/A Conversions from LTIP units to Other Common Units (165,672 ) 165,672 — N/A Redemptions from Other Common Units to common stock — (352,055 ) (352,055 ) N/A Balance at December 31, 2018 1,616,200 2,453,234 4,069,434 3.5 % Granted/Issued 364,173 — 364,173 N/A Forfeited (10,208 ) — (10,208 ) N/A Conversions from LTIP units to Other Common Units (202,173 ) 202,173 — N/A Redemptions from Other Common Units to common stock — (439,071 ) (439,071 ) N/A Balance at March 31, 2019 1,767,992 2,216,336 3,984,328 3.3 % LTIP Units LTIP units granted on January 7, 2019 to non-employee, independent directors, subject to the recipient’s continued service, will vest on January 1, 2020. LTIP units granted on January 7, 2019 to certain senior executive officers and senior employees, subject to the recipient’s continued employment, will vest quarterly over four years, with the first vesting date having been March 31, 2019. Refer to Note 8 for a discussion of the LTIP units granted on January 7, 2019 pursuant to the March 8, 2016 performance units. The fair value of the LTIP units at the date of grant was determined by a lattice-binomial option-pricing model based on a Monte Carlo simulation. The fair value of the LTIP units are based on Level 3 inputs and are non-recurring fair value measurements. The table below sets forth the assumptions used in valuing such LTIP units granted during the three months ended March 31, 2019 (excluding those LTIP units granted pursuant to the March 8, 2016 performance units; refer to Note 8 for details). LTIP Units Assumptions Grant date January 7, 2019 Expected term (years) 10 Expected volatility 19.0 % Expected dividend yield 6.0 % Risk-free interest rate 2.57 % Fair value of LTIP units at issuance (in thousands) $ 3,636 LTIP units at issuance 154,649 Fair value unit price per LTIP unit at issuance $ 23.51 The following table summarizes activity related to the Company’s unvested LTIP units for the three months ended March 31, 2019 and the year ended December 31, 2018 . Unvested LTIP Units LTIP Units Balance at December 31, 2017 300,307 Granted 324,802 Vested (373,893 ) Forfeited — Balance at December 31, 2018 251,216 Granted 364,173 Vested (157,689 ) Forfeited (10,208 ) Balance at March 31, 2019 447,492 The unrecognized compensation expense associated with the Company’s LTIP units at March 31, 2019 was approximately $7.3 million and is expected to be recognized over a weighted average period of approximately 2.6 years . The following table summarizes the fair value at vesting for the LTIP units that vested during the three months ended March 31, 2019 and 2018 . Three months ended March 31, Vested LTIP units 2019 2018 Vested LTIP units 157,689 231,041 Fair value of vested LTIP units (in thousands) $ 4,063 $ 6,035

Equity Incentive Plan

Equity Incentive Plan	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Equity Incentive Plan	Equity Incentive Plan On January 7, 2019 , the Company granted performance units approved by the compensation committee of the board of directors, under the 2011 Plan to certain key employees of the Company. The terms of the performance units granted on January 7, 2019 are substantially the same as the terms of the performance units granted on January 5, 2018 and January 6, 2017, except that the measuring period commences on January 1, 2019 and ends on December 31, 2021, and the award shares are immediately vested at the end of the measuring period. The fair value of the performance units at the date of grant was determined by a lattice-binomial option-pricing model based on a Monte Carlo simulation. The fair value of the performance units are based on Level 3 inputs and are non-recurring fair value measurements. The performance unit equity compensation expense is recognized ratably from the grant date into earnings over the vesting period. The table below sets forth the assumptions used in valuing the performance units granted during the three months ended March 31, 2019 . Performance Units Assumptions Grant date January 7, 2019 Expected volatility 20.7 % Expected dividend yield 6.0 % Risk-free interest rate 2.56 % Fair value of performance units grant (in thousands) $ 5,620 On December 31, 2018, the Company’s three year measurement period pursuant to the March 8, 2016 performance units concluded. It was determined that the Company’s total stockholder return exceeded the threshold percentage and return hurdle. The compensation committee of the board of directors approved the issuance of 102,216 vested LTIP units and 74,032 vested shares of common stock (of which 30,193 shares of common stock were repurchased and retired) to the participants, which were issued on January 7, 2019 . The compensation committee of the board of directors also approved the issuance of 107,308 LTIP units and 22,678 restricted shares of common stock that will vest on December 31, 2019, which were issued on January 7, 2019 . The unrecognized compensation expense associated with the Company’s performance units at March 31, 2019 was approximately $9.2 million and is expected to be recognized over a weighted average period of approximately 2.4 years . Non-cash Compensation Expense The following table summarizes the amount recorded in general and administrative expenses in the accompanying Consolidated Statements of Operations for the amortization of restricted shares of common stock, LTIP units, performance units, and the Company’s director compensation for the three months ended March 31, 2019 and 2018 . Three months ended March 31, Non-Cash Compensation Expense (in thousands) 2019 2018 Restricted shares of common stock $ 427 $ 434 LTIP units 887 871 Performance units 859 829 Director compensation (1) 105 86 Total non-cash compensation expense $ 2,278 $ 2,220 (1) All of the Company’s independent directors elected to receive shares of common stock in lieu of cash for their service during the three months ended March 31, 2019 and 2018 . The number of shares of common stock granted is calculated based on the trailing 10 days average common stock price ending on the third business day preceding the grant date.

Leases

Leases	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Leases	Leases Lessor Leases The Company has operating leases in which it is the lessor for its rental property. Certain leases contain variable lease payments based upon changes in the Consumer Price Index (“CPI”). Certain leases contain options to renew or terminate the lease, and options for the lessee to purchase the rental property, all of which are predominately at the sole discretion of the lessee. The following table summarizes the components of rental income recognized during the three months ended March 31, 2019 included in the accompanying Consolidated Statements of Operations. Three months ended March 31, Rental Income (in thousands) 2019 Fixed lease payments $ 72,117 Variable lease payments 22,181 Straight-line rental income 2,284 Net decrease to rental income related to above and below market lease amortization (967 ) Total rental income $ 95,615 As of March 31, 2019 and December 31, 2018 , the Company had accrued rental income of approximately $34.2 million and $32.4 million , respectively, included in tenant accounts receivable on the accompanying Consolidated Balance Sheets. As of March 31, 2019 and December 31, 2018 , the Company had approximately $18.4 million and $18.3 million , respectively, of total lease security deposits available in the form of existing letters of credit, which are not reflected on the accompanying Consolidated Balance Sheets. As of March 31, 2019 and December 31, 2018 , the Company had approximately $0.7 million and $0.7 million , respectively, of lease security deposits available in cash, which are included in restricted cash on the accompanying Consolidated Balance Sheets. The Company’s remaining lease security deposits are commingled in cash and cash equivalents. These funds may be used to settle tenant accounts receivables in the event of a default under the related lease. As of March 31, 2019 and December 31, 2018 , the Company’s total liability associated with these lease security deposits was approximately $8.7 million and $8.4 million , respectively, and is included in tenant prepaid rent and security deposits on the accompanying Consolidated Balance Sheets. The Company estimates that billings for real estate taxes, which are the responsibility of certain tenants under the terms of their leases and are not reflected on the Company’s consolidated financial statements, were approximately $3.9 million and $3.1 million for the three months ended March 31, 2019 and 2018 , respectively. These amounts would have been the maximum real estate tax expense of the Company, excluding any penalties or interest, had the tenants not met their contractual obligations for these periods. The following table summarizes the maturity of fixed lease payments under the Company’s leases as of March 31, 2019 . Year (as of March 31, 2019) Maturity of Fixed Lease Payments (in thousands) Remainder of 2019 $ 240,185 2020 $ 288,787 2021 $ 243,992 2022 $ 203,368 2023 $ 165,946 Thereafter $ 578,495 The following table summarizes the minimum contractual lease payments under the superseded leases standard, Topic 840, as of December 31, 2018 . Year (as of December 31, 2018) Future Minimum Rents (in thousands) 2019 $ 299,978 2020 $ 271,936 2021 $ 226,970 2022 $ 188,707 2023 $ 152,814 Thereafter $ 535,192 Lessee Leases The Company has operating leases in which it is the lessee for ground leases and its corporate office lease. These leases have remaining lease terms of approximately 2.0 years to 47.8 years . Certain ground leases contain options to extend the leases for ten years to 20 years , all of which are reasonably certain to be exercised, and are included in the computation of the Company’s right-of-use assets and operating lease liabilities. The following table summarizes supplemental information related to operating lease right-of-use assets and operating lease liabilities recognized in the Company’s Consolidated Balance Sheets as of March 31, 2019 . Operating Lease Term and Discount Rate March 31, 2019 Weighted average remaining lease term (years) 35.1 Weighted average discount rate 7.1 % The following table summarizes the operating lease cost recognized during the three months ended March 31, 2019 included in the Company’s Consolidated Statements of Operations. Three months ended March 31, Operating Lease Cost (in thousands) 2019 Operating lease cost included in property expense attributable to ground leases $ 331 Operating lease cost included in general and administrative expense attributable to corporate office lease 266 Total operating lease cost $ 597 The following table summarizes supplemental cash flow information related to operating leases recognized during the three months ended March 31, 2019 in the Company’s Consolidated Statements of Cash Flows. Three months ended March 31, Operating Leases (in thousands) 2019 Cash paid for amounts included in the measurement of lease liabilities (operating cash flows) $ 569 The following table summarizes the maturity of operating lease liabilities under the Company’s ground leases and corporate office lease as of March 31, 2019 . Year (as of March 31, 2019) Maturity of Operating Lease Liabilities (1) (in thousands) Remainder of 2019 $ 1,712 2020 2,294 2021 1,400 2022 1,107 2023 1,116 Thereafter 48,155 Total lease payments 55,784 Less: Imputed interest (37,998 ) Present value of operating lease liabilities $ 17,786 (1) Operating lease liabilities do not include estimates of CPI rent changes required by certain ground lease agreements. Therefore, actual payments may differ than those presented. The following table summarizes the minimum contractual lease payments under the superseded leases standard, Topic 840, as of December 31, 2018. Year (as of December 31, 2018) Future Minimum Rental Payments (1) (in thousands) 2019 $ 2,110 2020 $ 2,122 2021 $ 1,227 2022 $ 935 2023 $ 944 Thereafter $ 45,580 (1) Future minimum rental payments do not include estimates of CPI rent changes required by certain lease agreements. Therefore, actual minimum rental payments may differ than those presented.
Leases	Leases Lessor Leases The Company has operating leases in which it is the lessor for its rental property. Certain leases contain variable lease payments based upon changes in the Consumer Price Index (“CPI”). Certain leases contain options to renew or terminate the lease, and options for the lessee to purchase the rental property, all of which are predominately at the sole discretion of the lessee. The following table summarizes the components of rental income recognized during the three months ended March 31, 2019 included in the accompanying Consolidated Statements of Operations. Three months ended March 31, Rental Income (in thousands) 2019 Fixed lease payments $ 72,117 Variable lease payments 22,181 Straight-line rental income 2,284 Net decrease to rental income related to above and below market lease amortization (967 ) Total rental income $ 95,615 As of March 31, 2019 and December 31, 2018 , the Company had accrued rental income of approximately $34.2 million and $32.4 million , respectively, included in tenant accounts receivable on the accompanying Consolidated Balance Sheets. As of March 31, 2019 and December 31, 2018 , the Company had approximately $18.4 million and $18.3 million , respectively, of total lease security deposits available in the form of existing letters of credit, which are not reflected on the accompanying Consolidated Balance Sheets. As of March 31, 2019 and December 31, 2018 , the Company had approximately $0.7 million and $0.7 million , respectively, of lease security deposits available in cash, which are included in restricted cash on the accompanying Consolidated Balance Sheets. The Company’s remaining lease security deposits are commingled in cash and cash equivalents. These funds may be used to settle tenant accounts receivables in the event of a default under the related lease. As of March 31, 2019 and December 31, 2018 , the Company’s total liability associated with these lease security deposits was approximately $8.7 million and $8.4 million , respectively, and is included in tenant prepaid rent and security deposits on the accompanying Consolidated Balance Sheets. The Company estimates that billings for real estate taxes, which are the responsibility of certain tenants under the terms of their leases and are not reflected on the Company’s consolidated financial statements, were approximately $3.9 million and $3.1 million for the three months ended March 31, 2019 and 2018 , respectively. These amounts would have been the maximum real estate tax expense of the Company, excluding any penalties or interest, had the tenants not met their contractual obligations for these periods. The following table summarizes the maturity of fixed lease payments under the Company’s leases as of March 31, 2019 . Year (as of March 31, 2019) Maturity of Fixed Lease Payments (in thousands) Remainder of 2019 $ 240,185 2020 $ 288,787 2021 $ 243,992 2022 $ 203,368 2023 $ 165,946 Thereafter $ 578,495 The following table summarizes the minimum contractual lease payments under the superseded leases standard, Topic 840, as of December 31, 2018 . Year (as of December 31, 2018) Future Minimum Rents (in thousands) 2019 $ 299,978 2020 $ 271,936 2021 $ 226,970 2022 $ 188,707 2023 $ 152,814 Thereafter $ 535,192 Lessee Leases The Company has operating leases in which it is the lessee for ground leases and its corporate office lease. These leases have remaining lease terms of approximately 2.0 years to 47.8 years . Certain ground leases contain options to extend the leases for ten years to 20 years , all of which are reasonably certain to be exercised, and are included in the computation of the Company’s right-of-use assets and operating lease liabilities. The following table summarizes supplemental information related to operating lease right-of-use assets and operating lease liabilities recognized in the Company’s Consolidated Balance Sheets as of March 31, 2019 . Operating Lease Term and Discount Rate March 31, 2019 Weighted average remaining lease term (years) 35.1 Weighted average discount rate 7.1 % The following table summarizes the operating lease cost recognized during the three months ended March 31, 2019 included in the Company’s Consolidated Statements of Operations. Three months ended March 31, Operating Lease Cost (in thousands) 2019 Operating lease cost included in property expense attributable to ground leases $ 331 Operating lease cost included in general and administrative expense attributable to corporate office lease 266 Total operating lease cost $ 597 The following table summarizes supplemental cash flow information related to operating leases recognized during the three months ended March 31, 2019 in the Company’s Consolidated Statements of Cash Flows. Three months ended March 31, Operating Leases (in thousands) 2019 Cash paid for amounts included in the measurement of lease liabilities (operating cash flows) $ 569 The following table summarizes the maturity of operating lease liabilities under the Company’s ground leases and corporate office lease as of March 31, 2019 . Year (as of March 31, 2019) Maturity of Operating Lease Liabilities (1) (in thousands) Remainder of 2019 $ 1,712 2020 2,294 2021 1,400 2022 1,107 2023 1,116 Thereafter 48,155 Total lease payments 55,784 Less: Imputed interest (37,998 ) Present value of operating lease liabilities $ 17,786 (1) Operating lease liabilities do not include estimates of CPI rent changes required by certain ground lease agreements. Therefore, actual payments may differ than those presented. The following table summarizes the minimum contractual lease payments under the superseded leases standard, Topic 840, as of December 31, 2018. Year (as of December 31, 2018) Future Minimum Rental Payments (1) (in thousands) 2019 $ 2,110 2020 $ 2,122 2021 $ 1,227 2022 $ 935 2023 $ 944 Thereafter $ 45,580 (1) Future minimum rental payments do not include estimates of CPI rent changes required by certain lease agreements. Therefore, actual minimum rental payments may differ than those presented.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share During the three months ended March 31, 2019 and 2018 , there were 213,856 and 201,650 , respectively, of unvested restricted shares of common stock on a weighted average basis that were considered participating securities. The following table sets forth the computation of basic and diluted earnings per common share for the three months ended March 31, 2019 and 2018 . Three months ended March 31, Earnings Per Share (in thousands, except per share data) 2019 2018 Numerator Net income $ 7,389 $ 25,149 Less: preferred stock dividends 1,289 2,448 Less: amount allocated to participating securities 79 71 Less: income attributable to noncontrolling interest after preferred stock dividends 214 954 Net income attributable to common stockholders $ 5,807 $ 21,676 Denominator Weighted average common shares outstanding — basic 114,721 97,021 Effect of dilutive securities (1) Share-based compensation 272 302 Weighted average common shares outstanding — diluted 114,993 97,323 Net income per share — basic and diluted Net income per share attributable to common stockholders — basic $ 0.05 $ 0.22 Net income per share attributable to common stockholders — diluted $ 0.05 $ 0.22 (1) During the three months ended March 31, 2019 and 2018 , there were 214 and 202 , unvested shares of restricted common stock, respectively, on a weighted average basis that were not included in the computation of diluted earnings per share because the allocation of income under the two-class method was more dilutive.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies The Company is subject to various legal proceedings and claims that arise in the ordinary course of business. These matters are generally covered by insurance subject to deductible requirements. Management believes that the ultimate settlement of these actions will not have a material adverse effect on the Company’s financial position, results of operations, or cash flows. The Company has letters of credit of approximately $5.6 million as of March 31, 2019 related to construction projects and certain other agreements. As of March 31, 2019, the Company has a development commitment related to a building expansion under a tenant lease of approximately $9.8 million .

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2019
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events The following non-recognized subsequent events were noted. On April 1, 2019 , the Company completed an underwritten public offering of 7,475,000 shares of common stock (including 975,000 shares issued pursuant to the underwriters’ option to purchase additional shares) at a price to the underwriters of $28.72 per share. The offering closed on April 4, 2019 and the Company received net proceeds of approximately $214.7 million . On April 30, 2019, the Company filed Articles of Amendment to its Articles of Amendment and Restatement to increase the number of authorized shares of the Company’s common stock from 150,000,000 to 300,000,000 and the number of authorized shares of preferred stock from 15,000,000 to 20,000,000 .

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Quarterly Financial Information	Interim Financial Information The accompanying interim financial statements have been presented in conformity with accounting principles generally accepted in the United States of America (“GAAP”) and with the instructions to Form 10-Q and Regulation S-X for interim financial information. Accordingly, these statements do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, the accompanying interim financial statements include all adjustments, consisting of normal recurring items, necessary for their fair statement in conformity with GAAP. Interim results are not necessarily indicative of results for a full year. The year-end consolidated balance sheet data was derived from audited financial statements, but does not include all disclosures required by GAAP. The information included in this Quarterly Report on Form 10-Q should be read in conjunction with the Company’s consolidated financial statements and notes thereto contained in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2018 .
Basis of Presentation	Basis of Presentation The Company’s consolidated financial statements include the accounts of the Company, the Operating Partnership, and their subsidiaries. Interests in the Operating Partnership not owned by the Company are referred to as “Noncontrolling Common Units.” These Noncontrolling Common Units are held by other limited partners in the form of common units (“Other Common Units”) and long term incentive plan units (“LTIP units”) issued pursuant to the STAG Industrial, Inc. 2011 Equity Incentive Plan, as amended and restated (the “2011 Plan”). All significant intercompany balances and transactions have been eliminated in the consolidation of entities. The financial statements of the Company are presented on a consolidated basis for all periods presented.
New Accounting Pronouncements	New Accounting Standards Adopted In July 2018, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2018-11 which amends Topic 842, Leases , and provides lessors with a practical expedient, by class of underlying asset, to not separate non-lease components from the associated lease component and, instead, to account for those components as a single component if the non-lease components otherwise would be accounted for under the new revenue guidance and both of the following are met: i) the timing and pattern of transfer of the non-lease component(s) and associated lease component are the same; and ii) the lease component, if accounted for separately, would be classified as an operating lease. Under this new expedient, if the non-lease components associated with the lease component are the predominant component of the combined component, a company should account for the combined component in accordance with Topic 606, Revenue from Contracts with Customers . Otherwise, the company should account for the combined component as an operating lease in accordance with Topic 842. In December 2018, the FASB issued ASU 2018-20 which amends Topic 842, Leases , and allows lessors to continue to exclude from revenue the lessor costs that are paid by lessees directly to third parties. The Company adopted Topic 842 on January 1, 2019, using the practical expedient, and it did not have a material impact on the Company’s consolidated financial statements. The Company determined that for all leases where the Company is the lessor, that the timing and pattern of transfer of the non-lease components and associated lease components are the same, and that the lease components, if accounted for separately, would be classified as an operating lease. Accordingly, the Company has made an accounting policy election to recognize the combined component in accordance with Topic 842 as rental income on the accompanying Consolidated Statements of Operations. In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) , and various subsequent ASU’s, which set out the principles for the recognition, measurement, presentation and disclosure of leases for both parties to a contract (i.e. lessees and lessors). Topic 842 superseded the previous leases standard, Topic 840, Leases . The new standard requires lessees to apply a dual approach, classifying leases as either finance or operating leases based on the principle of whether or not the lease is effectively a financed purchase by the lessee. This classification determines whether lease expense is recognized based on an effective interest method or on a straight line basis over the term of the lease, respectively. A lessee is also required to record a right-of-use asset and a lease liability for all leases with a term of greater than 12 months regardless of their classification. Leases with a term of 12 months or less are accounted for similar to the previous guidance for operating leases. The new standard requires lessors to account for leases using an approach that is substantially equivalent to the previous guidance for sales-type leases, direct financing leases and operating leases. ASU 2016-02 impacted the Company’s consolidated financial statements as the Company has ground leases and its corporate office lease for which it is the lessee, which resulted in the recording of a right-of-use asset and the related lease liability. The Company adopted ASU 2016-02 on January 1, 2019, using the modified retrospective transition method. The adoption of this standard resulted in a cumulative effect adjustment of approximately $0.2 million recorded as an increase to cumulative dividends in excess of earnings as of January 1, 2019 in the accompanying Consolidated Statements of Equity. The cumulative effect adjustment related to initial direct costs of leases where the Company is the lessor and that, as of January 1, 2019, had not begun to amortize and are no longer allowed to be capitalized under the new standard. On January 1, 2019, the Company recognized operating lease right-of-use assets of approximately $16.3 million and related operating lease liabilities of approximately $18.0 million on the accompanying Consolidated Balance Sheets, related to the leases where the Company is the lessee. The Company adopted the new standard using the practical expedient package which allowed the Company to (i) not reassess whether any expired or existing contracts are or contain leases; (ii) not reassess the lease classification for any expired or existing leases; and (iii) not reassess initial direct costs for any existing leases. This practical expedient allows the Company to continue to account for its ground leases as operating leases. Prospectively, any new or modified ground leases may be classified as a financing lease. The adoption of this standard by the Company has been applied prospectively, and the comparative periods have not been restated. For leases in which the Company is the lessee, the Company recognizes a right-of-use asset and corresponding lease liability on the accompanying Consolidated Balance Sheets equal to the present value of the fixed lease payments. In determining operating right-of-use asset and lease liability for the Company’s existing operating leases upon the adoption of the new lease guidance, the Company was required to estimate an appropriate incremental borrowing rate on a fully-collateralized basis for the terms of the leases. The Company utilized a market-based approach to estimate the incremental borrowing rate for each individual lease. Since the terms under the ground leases are significantly longer than the terms of borrowings available to the Company on a fully-collateralized basis, the estimate of this rate required significant judgment, and considered factors such as yields on outstanding public debt and other market based pricing on longer duration financing instruments. The new leases standard requires the Company to evaluate cash basis versus accrual basis of rental income recognition based on the collectability of future lease payments.
Reclassification	Reclassifications Prior period amounts have been reclassified to conform to the current year presentation due to the adoption of ASU 2016-02. Amounts previously classified as rental income and tenant recoveries in the prior period are now classified as rental income on the accompanying Consolidated Statements of Operations, as the Company has made an accounting policy election to combine these amounts that are accounted for under the new leases standard.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Cash, Cash Equivalents and Restricted Cash (Tables)	3 Months Ended
	Mar. 31, 2019
Accounting Policies [Abstract]
Schedule of Cash, Cash Equivalents and Restricted Cash	The following table presents a reconciliation of cash and cash equivalents and restricted cash reported on the accompanying Consolidated Balance Sheets to amounts reported on the accompanying Consolidated Statements of Cash Flows. Reconciliation of cash and cash equivalents and restricted cash (in thousands) March 31, 2019 December 31, 2018 Cash and cash equivalents $ 7,857 $ 7,968 Restricted cash 4,451 14,574 Total cash and cash equivalents and restricted cash $ 12,308 $ 22,542

Rental Property (Tables)

Rental Property (Tables)	3 Months Ended
	Mar. 31, 2019
Real Estate [Abstract]
Schedule of components of rental property	The following table summarizes the components of rental property as of March 31, 2019 and December 31, 2018 . Rental Property (in thousands) March 31, 2019 December 31, 2018 Land $ 377,530 $ 364,023 Buildings, net of accumulated depreciation of $211,755 and $199,497, respectivel y 2,180,636 2,082,781 Tenant improvements, net of accumulated depreciation of $21,026 and $36,450, respectively 31,108 30,704 Building and land improvements, net of accumulated depreciation of $88,229 and $80,983, respectivel y 173,715 168,229 Construction in progress 7,088 3,949 Deferred leasing intangibles, net of accumulated amortization of $224,740 and $246,502, respectively 348,439 342,015 Total rental property, net $ 3,118,516 $ 2,991,701
Schedule of real estate properties acquired	The following table summarizes the acquisitions of the Company during the three months ended March 31, 2019 . Market (1) Date Acquired Square Feet Buildings Purchase Price Cincinnati/Dayton, OH January 24, 2019 176,000 1 $ 9,965 Pittsburgh, PA February 21, 2019 455,000 1 28,676 Boston, MA February 21, 2019 349,870 1 26,483 Minneapolis/St Paul, MN February 28, 2019 248,816 1 21,955 Greenville/Spartanburg, SC March 7, 2019 331,845 1 24,536 Philadelphia, PA March 7, 2019 148,300 1 10,546 Omaha/Council Bluffs, NE-IA March 11, 2019 237,632 1 20,005 Houston, TX March 28, 2019 132,000 1 17,307 Baltimore, MD March 28, 2019 167,410 1 13,648 Houston, TX March 28, 2019 116,750 1 12,242 Three months ended March 31, 2019 2,363,623 10 $ 185,363
Summary of allocation of the consideration paid for the acquired assets and liabilities in connection with the acquisition of buildings at the date of acquisition	The following table summarizes the allocation of the consideration paid at the date of acquisition during the three months ended March 31, 2019 for the acquired assets and liabilities in connection with the acquisitions identified in the table above. Acquired Assets and Liabilities Purchase Price (in thousands) Weighted Average Amortization Period (years) of Intangibles at Acquisition Land $ 18,152 N/A Buildings 127,201 N/A Tenant improvements 1,349 N/A Building and land improvements 11,235 N/A Construction in progress 2,032 N/A Other assets 1,049 N/A Deferred leasing intangibles - In-place leases 16,743 7.9 Deferred leasing intangibles - Tenant relationships 8,404 11.3 Deferred leasing intangibles - Above market leases 327 4.3 Deferred leasing intangibles - Below market leases (1,129 ) 8.5 Total purchase price $ 185,363
Schedule of pro forma information for acquired properties	The table below sets forth the results of operations for the three months ended March 31, 2019 for the buildings acquired during the three months ended March 31, 2019 included in the Company’s Consolidated Statements of Operations from the date of acquisition. Results of Operations (in thousands) Three months ended March 31, 2019 Total revenue $ 1,194 Net loss $ 145
Impaired Assets to be Disposed of by Method Other than Sale [Table Text Block]	Loss on Impairments The following table summarizes the Company's loss on impairments for assets held and used during the three months ended March 31, 2019 . Market (1) Buildings Event or Change in Circumstance Leading to Impairment Evaluation (2) Valuation technique utilized to estimate fair value Fair Value (3) Loss on Impairments (in thousands) Rapid City, SD 1 Change in estimated hold period Discounted cash flows (4) Three months ended March 31, 2019 $ 4,373 $ 5,344 (1) As defined by CoStar. If the building is located outside of a CoStar defined market, the city and state is reflected. (2) The Company tested the asset group for impairment utilizing a probability weighted recovery analysis of certain scenarios, and it was determined that the carrying value of the property and intangibles were not recoverable from the estimated future undiscounted cash flows. (3) The estimated fair value of the property is based on Level 3 inputs and is a non-recurring fair value measurement. Level 3 is defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. (4) Level 3 inputs used to determine fair value for the property impaired for the three months ended March 31, 2019 : discount rate of 12.0% and exit capitalization rate of 12.0% .
Schedule of Finite-Lived Intangible Assets and Below Market Leases	The following table sets forth the deferred leasing intangibles on the accompanying Consolidated Balance Sheets as of March 31, 2019 and December 31, 2018 . March 31, 2019 December 31, 2018 Deferred Leasing Intangibles (in thousands) Gross Accumulated Amortization Net Gross Accumulated Amortization Net Above market leases $ 70,961 $ (30,409 ) $ 40,552 $ 73,122 $ (31,059 ) $ 42,063 Other intangible lease assets 502,218 (194,331 ) 307,887 515,395 (215,443 ) 299,952 Total deferred leasing intangible assets $ 573,179 $ (224,740 ) $ 348,439 $ 588,517 $ (246,502 ) $ 342,015 Below market leases $ 30,862 $ (10,394 ) $ 20,468 $ 34,331 $ (12,764 ) $ 21,567 Total deferred leasing intangible liabilities $ 30,862 $ (10,394 ) $ 20,468 $ 34,331 $ (12,764 ) $ 21,567 The following table sets forth the amortization expense and the net decrease to rental income for the amortization of deferred leasing intangibles during the three months ended March 31, 2019 and 2018 . Three months ended March 31, Deferred Leasing Intangibles Amortization (in thousands) 2019 2018 Net decrease to rental income related to above and below market lease amortization $ 967 $ 1,207 Amortization expense related to other intangible lease assets $ 16,814 $ 18,100
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The following table sets forth the amortization of deferred leasing intangibles over the next five calendar years beginning with 2019 as of March 31, 2019 . Year Amortization Expense Related to Other Intangible Lease Assets (in thousands) Net Decrease to Rental Income Related to Above and Below Market Lease Amortization (in thousands) Remainder of 2019 $ 48,278 $ 2,900 2020 $ 54,265 $ 3,546 2021 $ 43,369 $ 2,221 2022 $ 35,017 $ 1,361 2023 $ 28,732 $ 1,363
Below Market Lease, Future Amortization Income	The following table sets forth the amortization of deferred leasing intangibles over the next five calendar years beginning with 2019 as of March 31, 2019 . Year Amortization Expense Related to Other Intangible Lease Assets (in thousands) Net Decrease to Rental Income Related to Above and Below Market Lease Amortization (in thousands) Remainder of 2019 $ 48,278 $ 2,900 2020 $ 54,265 $ 3,546 2021 $ 43,369 $ 2,221 2022 $ 35,017 $ 1,361 2023 $ 28,732 $ 1,363

Debt (Tables)

Debt (Tables)	3 Months Ended
	Mar. 31, 2019
Debt Disclosure [Abstract]
Summary of the mortgage notes payable, unsecured term loans and credit facility	The following table sets forth a summary of the Company’s outstanding indebtedness, including borrowings under the Company’s unsecured credit facility, unsecured term loans, unsecured notes, and mortgage notes as of March 31, 2019 and December 31, 2018 . Loan Principal Outstanding as of March 31, 2019 (in thousands) Principal Outstanding as of December 31, 2018 (in thousands) Interest (1)(2) Maturity Date Prepayment Terms (3) Unsecured credit facility: Unsecured Credit Facility (4) $ 115,500 $ 100,500 L + 0.90% Jan-15-2023 i Total unsecured credit facility 115,500 100,500 Unsecured term loans: Unsecured Term Loan C 150,000 150,000 2.39 % Sep-29-2020 i Unsecured Term Loan B 150,000 150,000 3.05 % Mar-21-2021 i Unsecured Term Loan A 150,000 150,000 2.70 % Mar-31-2022 i Unsecured Term Loan D 150,000 150,000 2.85 % Jan-04-2023 i Unsecured Term Loan E (5) — — 3.92 % Jan-15-2024 i Total unsecured term loans 600,000 600,000 Less: Total unamortized deferred financing fees and debt issuance costs (3,358 ) (3,640 ) Total carrying value unsecured term loans, net 596,642 596,360 Unsecured notes: Series F Unsecured Notes 100,000 100,000 3.98 % Jan-05-2023 ii Series A Unsecured Notes 50,000 50,000 4.98 % Oct-1-2024 ii Series D Unsecured Notes 100,000 100,000 4.32 % Feb-20-2025 ii Series G Unsecured Notes 75,000 75,000 4.10 % Jun-13-2025 ii Series B Unsecured Notes 50,000 50,000 4.98 % Jul-1-2026 ii Series C Unsecured Notes 80,000 80,000 4.42 % Dec-30-2026 ii Series E Unsecured Notes 20,000 20,000 4.42 % Feb-20-2027 ii Series H Unsecured Notes 100,000 100,000 4.27 % Jun-13-2028 ii Total unsecured notes 575,000 575,000 Less: Total unamortized deferred financing fees and debt issuance costs (2,413 ) (2,512 ) Total carrying value unsecured notes, net 572,587 572,488 Mortgage notes (secured debt): Wells Fargo Bank, National Association CMBS Loan 52,763 53,216 4.31 % Dec-1-2022 iii Thrivent Financial for Lutherans 3,767 3,795 4.78 % Dec-15-2023 iv Total mortgage notes 56,530 57,011 Add: Total unamortized fair market value premiums 48 50 Less: Total unamortized deferred financing fees and debt issuance costs (469 ) (501 ) Total carrying value mortgage notes, net 56,109 56,560 Total / weighted average interest rate (6) $ 1,340,838 $ 1,325,908 3.56 % (1) Interest rate as of March 31, 2019 . At March 31, 2019 , the one-month LIBOR (“L”) was 2.49450% . The current interest rate is not adjusted to include the amortization of deferred financing fees or debt issuance costs incurred in obtaining debt or any unamortized fair market value premiums. The spread over the applicable rate for the Company’s unsecured credit facility and unsecured term loans is based on the Company’s debt rating, as defined in the respective loan agreements. (2) As of March 31, 2019 , one-month LIBOR for the unsecured term loans A, B, C, D, and E was swapped to a fixed rate of 1.70% , 2.05% , 1.39% , 1.85% , and 2.92% , respectively. (3) Prepayment terms consist of (i) pre-payable with no penalty; (ii) pre-payable with penalty; (iii) pre-payable without penalty three months prior to the maturity date, however can be defeased; and (iv) pre-payable without penalty three months prior to the maturity date. (4) The capacity of the unsecured credit facility is $500.0 million . Deferred financing fees and debt issuance costs, net of accumulated amortization related to the unsecured credit facility of approximately $3.0 million and $3.2 million is included in prepaid expenses and other assets on the accompanying Consolidated Balance Sheets as of March 31, 2019 and December 31, 2018 , respectively. (5) Capacity of $175.0 million , which the Company has until July 25, 2019 to draw. (6) The weighted average interest rate was calculated using the fixed interest rate swapped on the notional amount of $600.0 million of debt, and is not adjusted to include the amortization of deferred financing fees or debt issuance costs incurred in obtaining debt or any unamortized fair market value premiums.
Interest Income and Interest Expense Disclosure [Table Text Block]	The table below sets forth the costs included in interest expense related to the Company’s debt arrangements on the accompanying Consolidated Statement of Operations for the three months ended March 31, 2019 and 2018 . Three months ended March 31, Costs Included in Interest Expense (in thousands) 2019 2018 Amortization of deferred financing fees and debt issuance costs and fair market value premiums $ 618 $ 534 Facility, unused, and other fees $ 383 $ 339
Schedule of aggregate carrying value of the debt and the corresponding estimate of fair value	The following table presents the aggregate principal outstanding under the Company’s debt arrangements and the corresponding estimate of fair value as of March 31, 2019 and December 31, 2018 (in thousands). March 31, 2019 December 31, 2018 Principal Outstanding Fair Value Principal Outstanding Fair Value Unsecured credit facility $ 115,500 $ 115,500 $ 100,500 $ 100,500 Unsecured term loans 600,000 600,000 600,000 600,000 Unsecured notes 575,000 596,833 575,000 585,292 Mortgage notes 56,530 57,494 57,011 57,289 Total principal amount 1,347,030 $ 1,369,827 1,332,511 $ 1,343,081 Add: Total unamortized fair market value premiums 48 50 Less: Total unamortized deferred financing fees and debt issuance costs (6,240 ) (6,653 ) Total carrying value $ 1,340,838 $ 1,325,908

Use of Derivative Financial I_2

Use of Derivative Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Instruments [Table Text Block]	The following table details the Company’s outstanding interest rate swaps as of March 31, 2019 . All of the Company’s interest rate swaps are designated as qualifying cash flow hedges. Interest Rate Trade Date Effective Date Notional Amount Fair Value Pay Fixed Interest Rate Receive Variable Interest Rate Maturity Date Regions Bank Mar-01-2013 Mar-01-2013 $ 25,000 $ 235 1.3300 % One-month L Feb-14-2020 Capital One, N.A. Jun-13-2013 Jul-01-2013 $ 50,000 $ 316 1.6810 % One-month L Feb-14-2020 Capital One, N.A. Jun-13-2013 Aug-01-2013 $ 25,000 $ 153 1.7030 % One-month L Feb-14-2020 Regions Bank Sep-30-2013 Feb-03-2014 $ 25,000 $ 90 1.9925 % One-month L Feb-14-2020 The Toronto-Dominion Bank Oct-14-2015 Sep-29-2016 $ 25,000 $ 342 1.3830 % One-month L Sep-29-2020 PNC Bank, N.A. Oct-14-2015 Sep-29-2016 $ 50,000 $ 678 1.3906 % One-month L Sep-29-2020 Regions Bank Oct-14-2015 Sep-29-2016 $ 35,000 $ 477 1.3858 % One-month L Sep-29-2020 U.S. Bank, N.A. Oct-14-2015 Sep-29-2016 $ 25,000 $ 338 1.3950 % One-month L Sep-29-2020 Capital One, N.A. Oct-14-2015 Sep-29-2016 $ 15,000 $ 202 1.3950 % One-month L Sep-29-2020 Royal Bank of Canada Jan-08-2015 Mar-20-2015 $ 25,000 $ 256 1.7090 % One-month L Mar-21-2021 The Toronto-Dominion Bank Jan-08-2015 Mar-20-2015 $ 25,000 $ 255 1.7105 % One-month L Mar-21-2021 The Toronto-Dominion Bank Jan-08-2015 Sep-10-2017 $ 100,000 $ 18 2.2255 % One-month L Mar-21-2021 Wells Fargo, N.A. Jan-08-2015 Mar-20-2015 $ 25,000 $ 243 1.8280 % One-month L Mar-31-2022 The Toronto-Dominion Bank Jan-08-2015 Feb-14-2020 $ 25,000 $ (204 ) 2.4535 % One-month L Mar-31-2022 Regions Bank Jan-08-2015 Feb-14-2020 $ 50,000 $ (430 ) 2.4750 % One-month L Mar-31-2022 Capital One, N.A. Jan-08-2015 Feb-14-2020 $ 50,000 $ (487 ) 2.5300 % One-month L Mar-31-2022 The Toronto-Dominion Bank Jul-20-2017 Oct-30-2017 $ 25,000 $ 269 1.8485 % One-month L Jan-04-2023 Royal Bank of Canada Jul-20-2017 Oct-30-2017 $ 25,000 $ 267 1.8505 % One-month L Jan-04-2023 Wells Fargo, N.A. Jul-20-2017 Oct-30-2017 $ 25,000 $ 267 1.8505 % One-month L Jan-04-2023 PNC Bank, N.A. Jul-20-2017 Oct-30-2017 $ 25,000 $ 269 1.8485 % One-month L Jan-04-2023 PNC Bank, N.A. Jul-20-2017 Oct-30-2017 $ 50,000 $ 539 1.8475 % One-month L Jan-04-2023 The Toronto-Dominion Bank Jul-24-2018 Jul-26-2019 $ 50,000 $ (1,696 ) 2.9180 % One-month L Jan-12-2024 PNC Bank, N.A. Jul-24-2018 Jul-26-2019 $ 50,000 $ (1,699 ) 2.9190 % One-month L Jan-12-2024 Bank of Montreal Jul-24-2018 Jul-26-2019 $ 50,000 $ (1,696 ) 2.9190 % One-month L Jan-12-2024 U.S. Bank, N.A. Jul-24-2018 Jul-26-2019 $ 25,000 $ (848 ) 2.9190 % One-month L Jan-12-2024
Schedule of interest rate swaps	The fair value of the interest rate swaps outstanding as of March 31, 2019 and December 31, 2018 was as follows. Balance Sheet Line Item (in thousands) Notional Amount March 31, 2019 Fair Value Notional Amount December 31, 2018 Fair Value December 31, 2018 Interest rate swaps-Asset $ 600,000 $ 5,214 $ 600,000 $ 9,151 Interest rate swaps-Liability $ 300,000 $ (7,060 ) $ 300,000 $ (4,011 )
Schedule of the location in the financial statements of the gain or loss recognized on interest rate swaps	The table below presents the effect of cash flow hedge accounting and the location in the consolidated financial statements for the three months ended March 31, 2019 and 2018 . Three months ended March 31, Effect of Cash Flow Hedge Accounting (in thousands) 2019 2018 Income (loss) recognized in accumulated other comprehensive income (loss) on interest rate swaps $ (5,856 ) $ 7,493 Income (loss) reclassified from accumulated other comprehensive income into income (loss) as interest expense $ 1,122 $ (230 ) Total interest expense presented in the Consolidated Statements of Operations in which the effects of cash flow hedges are recorded $ 12,834 $ 11,392
Schedule of financial instruments accounted for at fair value on a recurring basis	The following sets forth the Company’s financial instruments that are accounted for at fair value on a recurring basis as of March 31, 2019 and December 31, 2018 . Fair Value Measurements as of Balance Sheet Line Item (in thousands) Fair Value Level 1 Level 2 Level 3 Interest rate swaps-Asset $ 5,214 $ — $ 5,214 $ — Interest rate swaps-Liability $ (7,060 ) $ — $ (7,060 ) $ — Fair Value Measurements as of Balance Sheet Line Item (in thousands) Fair Value December 31, 2018 Level 1 Level 2 Level 3 Interest rate swaps-Asset $ 9,151 $ — $ 9,151 $ — Interest rate swaps-Liability $ (4,011 ) $ — $ (4,011 ) $ —

Equity (Tables)

Equity (Tables)	3 Months Ended
	Mar. 31, 2019
Stockholders' Equity Note [Abstract]
Schedule of Stock by Class	The table below sets forth the Company’s outstanding preferred stock issuances as of March 31, 2019 . Preferred Stock Issuances Issuance Date Number of Shares Liquidation Value Per Share Interest Rate 6.875% Series C Cumulative Redeemable Preferred Stock ("Series C Preferred Stock") March 17, 2016 3,000,000 $ 25.00 6.875 %
Schedule of dividends	The tables below sets forth the dividends attributable to the Company’s outstanding shares of common stock that were declared during the three months ended March 31, 2019 and the year ended December 31, 2018 . Month Ended 2019 Declaration Date Record Date Per Share Payment Date March 31 January 10, 2019 March 29, 2019 $ 0.119167 April 15, 2019 February 28 January 10, 2019 February 28, 2019 0.119167 March 15, 2019 January 31 January 10, 2019 January 31, 2019 0.119167 February 15, 2019 Total $ 0.357501 Month Ended 2018 Declaration Date Record Date Per Share Payment Date December 31 October 10, 2018 December 31, 2018 $ 0.118333 January 15, 2019 November 30 October 10, 2018 November 30, 2018 0.118333 December 17, 2018 October 31 October 10, 2018 October 31, 2018 0.118333 November 15, 2018 September 30 July 11, 2018 September 28, 2018 0.118333 October 15, 2018 August 31 July 11, 2018 August 31, 2018 0.118333 September 17, 2018 July 31 July 11, 2018 July 31, 2018 0.118333 August 15, 2018 June 30 April 10, 2018 June 29, 2018 0.118333 July 16, 2018 May 31 April 10, 2018 May 31, 2018 0.118333 June 15, 2018 April 30 April 10, 2018 April 30, 2018 0.118333 May 15, 2018 March 31 November 2, 2017 March 29, 2018 0.118333 April 16, 2018 February 28 November 2, 2017 February 28, 2018 0.118333 March 15, 2018 January 31 November 2, 2017 January 31, 2018 0.118333 February 15, 2018 Total $ 1.419996 On April 9, 2019 , the Company’s board of directors declared the common stock dividends for the months ending April 30, 2019 , May 31, 2019 and June 30, 2019 at a monthly rate of $0.119167 per share of common stock. The tables below set forth the dividends attributable to the Company’s outstanding preferred stock issuances during the three months ended March 31, 2019 and the year ended December 31, 2018 . Quarter Ended 2019 Declaration Date Series C Payment Date March 31 January 10, 2019 $ 0.4296875 April 1, 2019 Total $ 0.4296875 Quarter Ended 2018 Declaration Date Series B Series C Payment Date December 31 October 10, 2018 $ — $ 0.4296875 December 31, 2018 September 30 July 11, 2018 0.0460069 (1) 0.4296875 October 1, 2018 June 30 April 10, 2018 0.4140625 0.4296875 July 2, 2018 March 31 February 14, 2018 0.4140625 0.4296875 April 2, 2018 Total $ 0.8741319 $ 1.7187500 (1) On June 11, 2018, the Company gave notice to redeem all 2,800,000 issued and outstanding shares of the 6.625% Series B Cumulative Redeemable Preferred Stock (“Series B Preferred Stock”). On July 11, 2018, the Company redeemed all of the Series B Preferred Stock at a cash redemption price of $25.00 per share, plus accrued and unpaid dividends to but excluding the redemption date, without interest. On April 9, 2019 , the Company’s board of directors declared the Series C Preferred Stock dividends for the quarter ending June 30, 2019 at a quarterly rate of $0.4296875 per share.
Schedule of stock sale activity	The following table sets forth the terms of the Company’s at-the market (“ATM”) common stock offering program as of March 31, 2019 . ATM Common Stock Offering Program Date Maximum Aggregate Offering Price (in thousands) Aggregate Common Stock Available as of 2019 $600 million ATM February 14, 2019 $ 600,000 $ 449,811 The tables below set forth the activity under the ATM common stock offering programs during the three months ended March 31, 2019 and year ended December 31, 2018 (in thousands, except share data). Three months ended March 31, 2019 ATM Common Stock Offering Program Shares Weighted Average Price Per Share Gross Sales Net 2019 $600 million ATM 5,441,409 $ 27.60 $ 150,189 $ 1,302 $ 148,887 Total/weighted average 5,441,409 $ 27.60 $ 150,189 $ 1,302 $ 148,887 Year ended December 31, 2018 ATM Common Stock Offering Program Shares Weighted Average Price Per Share Gross Sales Net 2017 $500 million ATM (1) 14,724,614 $ 26.52 $ 390,447 $ 4,040 $ 386,407 Total/weighted average 14,724,614 $ 26.52 $ 390,447 $ 4,040 $ 386,407
Schedule of activity related to unvested restricted stock awards	The following table summarizes activity related to the Company’s unvested restricted shares of common stock for the three months ended March 31, 2019 and the year ended December 31, 2018 . Unvested Restricted Shares of Common Stock Shares Balance at December 31, 2017 237,207 Granted 76,659 (1) Vested (112,405 ) (2) Forfeited (10,999 ) Balance at December 31, 2018 190,462 Granted 110,830 (1) Vested (78,431 ) (2) Forfeited (2,320 ) Balance at March 31, 2019 220,541 (1) The fair value per share on the grant date of January 7, 2019 and January 5, 2018 was $24.85 and $26.40 , respectively. (2) The Company repurchased and retired 58,697 and 41,975 restricted shares of common stock that vested during the three months ended March 31, 2019 and the year ended December 31, 2018 , respectively.
Schedule of vested restricted shares of common stock activity	The following table summarizes the fair value at vesting for the restricted shares of common stock that vested during the three months ended March 31, 2019 and 2018 . Three months ended March 31, Vested Restricted Shares of Common Stock 2019 2018 Vested restricted shares of common stock 78,431 112,405 Fair value of vested restricted shares of common stock (in thousands) $ 1,951 $ 3,002

Noncontrolling Interest (Tables

Noncontrolling Interest (Tables)	3 Months Ended
	Mar. 31, 2019
Noncontrolling Interest [Abstract]
Noncontrolling interest activity	The table below summarizes the activity for noncontrolling interest in the Company for the three months ended March 31, 2019 and the year ended December 31, 2018 . Noncontrolling Interest LTIP Units Other Common Units Total Noncontrolling Common Units Noncontrolling Interest Balance at December 31, 2017 1,457,070 2,639,617 4,096,687 4.1 % Granted/Issued 324,802 — 324,802 N/A Forfeited — — — N/A Conversions from LTIP units to Other Common Units (165,672 ) 165,672 — N/A Redemptions from Other Common Units to common stock — (352,055 ) (352,055 ) N/A Balance at December 31, 2018 1,616,200 2,453,234 4,069,434 3.5 % Granted/Issued 364,173 — 364,173 N/A Forfeited (10,208 ) — (10,208 ) N/A Conversions from LTIP units to Other Common Units (202,173 ) 202,173 — N/A Redemptions from Other Common Units to common stock — (439,071 ) (439,071 ) N/A Balance at March 31, 2019 1,767,992 2,216,336 3,984,328 3.3 %
Schedule of share-based payment award, LTIP unit awards, valuation assumptions	The table below sets forth the assumptions used in valuing such LTIP units granted during the three months ended March 31, 2019 (excluding those LTIP units granted pursuant to the March 8, 2016 performance units; refer to Note 8 for details). LTIP Units Assumptions Grant date January 7, 2019 Expected term (years) 10 Expected volatility 19.0 % Expected dividend yield 6.0 % Risk-free interest rate 2.57 % Fair value of LTIP units at issuance (in thousands) $ 3,636 LTIP units at issuance 154,649 Fair value unit price per LTIP unit at issuance $ 23.51
Schedule of activity related to unvested LTIP unit awards	The following table summarizes activity related to the Company’s unvested LTIP units for the three months ended March 31, 2019 and the year ended December 31, 2018 . Unvested LTIP Units LTIP Units Balance at December 31, 2017 300,307 Granted 324,802 Vested (373,893 ) Forfeited — Balance at December 31, 2018 251,216 Granted 364,173 Vested (157,689 ) Forfeited (10,208 ) Balance at March 31, 2019 447,492
Schedule of vested LTIP unit award activity	The following table summarizes the fair value at vesting for the LTIP units that vested during the three months ended March 31, 2019 and 2018 . Three months ended March 31, Vested LTIP units 2019 2018 Vested LTIP units 157,689 231,041 Fair value of vested LTIP units (in thousands) $ 4,063 $ 6,035

Equity Incentive Plan (Tables)

Equity Incentive Plan (Tables)	3 Months Ended
	Mar. 31, 2019
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of share-based payment award, performance unit awards, valuation assumptions	The table below sets forth the assumptions used in valuing the performance units granted during the three months ended March 31, 2019 . Performance Units Assumptions Grant date January 7, 2019 Expected volatility 20.7 % Expected dividend yield 6.0 % Risk-free interest rate 2.56 % Fair value of performance units grant (in thousands) $ 5,620
Summary of Equity Compensation Expense	The following table summarizes the amount recorded in general and administrative expenses in the accompanying Consolidated Statements of Operations for the amortization of restricted shares of common stock, LTIP units, performance units, and the Company’s director compensation for the three months ended March 31, 2019 and 2018 . Three months ended March 31, Non-Cash Compensation Expense (in thousands) 2019 2018 Restricted shares of common stock $ 427 $ 434 LTIP units 887 871 Performance units 859 829 Director compensation (1) 105 86 Total non-cash compensation expense $ 2,278 $ 2,220 (1) All of the Company’s independent directors elected to receive shares of common stock in lieu of cash for their service during the three months ended March 31, 2019 and 2018 . The number of shares of common stock granted is calculated based on the trailing 10 days average common stock price ending on the third business day preceding the grant date.

Leases (Tables)

Leases (Tables)	3 Months Ended
	Mar. 31, 2019
Leases [Abstract]
Operating Lease, Lease Income [Table Text Block]	The following table summarizes the components of rental income recognized during the three months ended March 31, 2019 included in the accompanying Consolidated Statements of Operations. Three months ended March 31, Rental Income (in thousands) 2019 Fixed lease payments $ 72,117 Variable lease payments 22,181 Straight-line rental income 2,284 Net decrease to rental income related to above and below market lease amortization (967 ) Total rental income $ 95,615
Lessor, Operating Lease, Payments to be Received, Maturity	The following table summarizes the maturity of fixed lease payments under the Company’s leases as of March 31, 2019 . Year (as of March 31, 2019) Maturity of Fixed Lease Payments (in thousands) Remainder of 2019 $ 240,185 2020 $ 288,787 2021 $ 243,992 2022 $ 203,368 2023 $ 165,946 Thereafter $ 578,495
Schedule of minimum lease payments receivable	The following table summarizes the minimum contractual lease payments under the superseded leases standard, Topic 840, as of December 31, 2018 . Year (as of December 31, 2018) Future Minimum Rents (in thousands) 2019 $ 299,978 2020 $ 271,936 2021 $ 226,970 2022 $ 188,707 2023 $ 152,814 Thereafter $ 535,192 The following table summarizes the minimum contractual lease payments under the superseded leases standard, Topic 840, as of December 31, 2018. Year (as of December 31, 2018) Future Minimum Rental Payments (1) (in thousands) 2019 $ 2,110 2020 $ 2,122 2021 $ 1,227 2022 $ 935 2023 $ 944 Thereafter $ 45,580 (1) Future minimum rental payments do not include estimates of CPI rent changes required by certain lease agreements. Therefore, actual minimum rental payments may differ than those presented.
Lease, Cost [Table Text Block]	The following table summarizes supplemental information related to operating lease right-of-use assets and operating lease liabilities recognized in the Company’s Consolidated Balance Sheets as of March 31, 2019 . Operating Lease Term and Discount Rate March 31, 2019 Weighted average remaining lease term (years) 35.1 Weighted average discount rate 7.1 % The following table summarizes the operating lease cost recognized during the three months ended March 31, 2019 included in the Company’s Consolidated Statements of Operations. Three months ended March 31, Operating Lease Cost (in thousands) 2019 Operating lease cost included in property expense attributable to ground leases $ 331 Operating lease cost included in general and administrative expense attributable to corporate office lease 266 Total operating lease cost $ 597 The following table summarizes supplemental cash flow information related to operating leases recognized during the three months ended March 31, 2019 in the Company’s Consolidated Statements of Cash Flows. Three months ended March 31, Operating Leases (in thousands) 2019 Cash paid for amounts included in the measurement of lease liabilities (operating cash flows) $ 569
Lessee, Operating Lease, Liability, Maturity [Table Text Block]	The following table summarizes the maturity of operating lease liabilities under the Company’s ground leases and corporate office lease as of March 31, 2019 . Year (as of March 31, 2019) Maturity of Operating Lease Liabilities (1) (in thousands) Remainder of 2019 $ 1,712 2020 2,294 2021 1,400 2022 1,107 2023 1,116 Thereafter 48,155 Total lease payments 55,784 Less: Imputed interest (37,998 ) Present value of operating lease liabilities $ 17,786 (1) Operating lease liabilities do not include estimates of CPI rent changes required by certain ground lease agreements. Therefore, actual payments may differ than those presented.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2019
Earnings Per Share [Abstract]
Schedule of computation of basic and diluted earnings per common share	The following table sets forth the computation of basic and diluted earnings per common share for the three months ended March 31, 2019 and 2018 . Three months ended March 31, Earnings Per Share (in thousands, except per share data) 2019 2018 Numerator Net income $ 7,389 $ 25,149 Less: preferred stock dividends 1,289 2,448 Less: amount allocated to participating securities 79 71 Less: income attributable to noncontrolling interest after preferred stock dividends 214 954 Net income attributable to common stockholders $ 5,807 $ 21,676 Denominator Weighted average common shares outstanding — basic 114,721 97,021 Effect of dilutive securities (1) Share-based compensation 272 302 Weighted average common shares outstanding — diluted 114,993 97,323 Net income per share — basic and diluted Net income per share attributable to common stockholders — basic $ 0.05 $ 0.22 Net income per share attributable to common stockholders — diluted $ 0.05 $ 0.22 (1) During the three months ended March 31, 2019 and 2018 , there were 214 and 202 , unvested shares of restricted common stock, respectively, on a weighted average basis that were not included in the computation of diluted earnings per share because the allocation of income under the two-class method was more dilutive.

Organization and Description _2

Organization and Description of Business (Details) ft² in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2019ft²tenantstatebuilding	Dec. 31, 2018
Real Estate Properties [Line Items]
Ownership interest in Operating Partnership (as a percent)	96.70%	96.50%
Number of properties	395
Number of states in which the entity owned buildings | state	38
Area (in square feet) | ft²	78.2
Percentage of buildings leased to tenants	95.20%
Number of tenants | tenant	359
Warehouse - Distribution buildings
Real Estate Properties [Line Items]
Number of properties	328
Light Manufacturing buildings
Real Estate Properties [Line Items]
Number of properties	58
Flex/Office Buildings
Real Estate Properties [Line Items]
Number of properties	9

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - New Accounting Pronouncements (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease right-of-use assets	$ 16,005		$ 0
Operating lease liabilities	$ 17,786		$ 0
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to cumulative dividends in excess of earnings due to new accounting principle in period of adoption		$ (200)
Operating lease right-of-use assets		16,300
Operating lease liabilities		$ 18,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Restricted Cash (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Cash and cash equivalents	$ 7,857	$ 7,968
Restricted cash	4,451	14,574
Cash and cash equivalents and restricted cash—end of period	$ 12,308	$ 22,542	$ 17,714	$ 28,129

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Taxes (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Business Acquisition [Line Items]
Net income	$ 7,389,000	$ 25,149,000
State and local income, excise and franchise taxes	200,000	200,000
Liabilities for uncertain tax positions	0		$ 0
Real Estate Investment Trust
Business Acquisition [Line Items]
Net income	$ (12,000)	$ (36,000)

Rental Property - Summary (Deta

Rental Property - Summary (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property Subject to or Available for Operating Lease [Line Items]
Rental property, net	$ 3,118,516	$ 2,991,701
Deferred leasing intangibles assets, accumulated amortization	224,740	246,502
Land
Property Subject to or Available for Operating Lease [Line Items]
Rental property, net	377,530	364,023
Buildings, net of accumulated depreciation of $211,755 and $199,497, respectively
Property Subject to or Available for Operating Lease [Line Items]
Rental property, net	2,180,636	2,082,781
Rental property, accumulated depreciation	211,755	199,497
Tenant improvements, net of accumulated depreciation of $21,026 and $36,450, respectively
Property Subject to or Available for Operating Lease [Line Items]
Rental property, net	31,108	30,704
Rental property, accumulated depreciation	21,026	36,450
Building and land improvements, net of accumulated depreciation of $88,229 and $80,983, respectively
Property Subject to or Available for Operating Lease [Line Items]
Rental property, net	173,715	168,229
Rental property, accumulated depreciation	88,229	80,983
Construction in progress
Property Subject to or Available for Operating Lease [Line Items]
Rental property, net	7,088	3,949
Deferred leasing intangibles, net of accumulated amortization of $224,740 and $246,502, respectively
Property Subject to or Available for Operating Lease [Line Items]
Rental property, net	348,439	342,015
Deferred leasing intangibles assets, accumulated amortization	$ 224,740	$ 246,502

Rental Property - Acquisitions

Rental Property - Acquisitions (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)ft²building
Business Acquisition [Line Items]
Area (in square feet)	78,200,000
Acquisitions Q1 2019
Business Acquisition [Line Items]
Area (in square feet)	2,363,623
Number of Buildings Acquired | building	10
Business Combination, Consideration Transferred | $	$ 185,363
Florence, KY, 1-24-19 [Member]
Business Acquisition [Line Items]
Area (in square feet)	176,000
Number of Buildings Acquired | building	1
Business Combination, Consideration Transferred | $	$ 9,965
Burgettstown, PA, 2-21-19 [Member]
Business Acquisition [Line Items]
Area (in square feet)	455,000
Number of Buildings Acquired | building	1
Business Combination, Consideration Transferred | $	$ 28,676
Taunton, MA, 2-21-19 [Member]
Business Acquisition [Line Items]
Area (in square feet)	349,870
Number of Buildings Acquired | building	1
Business Combination, Consideration Transferred | $	$ 26,483
Blaine, MN, 2-28-19 [Member]
Business Acquisition [Line Items]
Area (in square feet)	248,816
Number of Buildings Acquired | building	1
Business Combination, Consideration Transferred | $	$ 21,955
Piedmont, SC, 3-7-19 [Member]
Business Acquisition [Line Items]
Area (in square feet)	331,845
Number of Buildings Acquired | building	1
Business Combination, Consideration Transferred | $	$ 24,536
York, PA, 3-7-19 [Member]
Business Acquisition [Line Items]
Area (in square feet)	148,300
Number of Buildings Acquired | building	1
Business Combination, Consideration Transferred | $	$ 10,546
Omaha, NE, 3-11-19 [Member]
Business Acquisition [Line Items]
Area (in square feet)	237,632
Number of Buildings Acquired | building	1
Business Combination, Consideration Transferred | $	$ 20,005
Humble, TX, 3-28-19 [Member]
Business Acquisition [Line Items]
Area (in square feet)	132,000
Number of Buildings Acquired | building	1
Business Combination, Consideration Transferred | $	$ 17,307
Elkridge, MD, 3-28-19 [Member]
Business Acquisition [Line Items]
Area (in square feet)	167,410
Number of Buildings Acquired | building	1
Business Combination, Consideration Transferred | $	$ 13,648
Houston, TX, 3-28-19 [Member]
Business Acquisition [Line Items]
Area (in square feet)	116,750
Number of Buildings Acquired | building	1
Business Combination, Consideration Transferred | $	$ 12,242

Rental Property - Acquisition_2

Rental Property - Acquisitions - Allocation of Consideration (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Allocation of the consideration paid for the acquired assets and liabilities
Land	$ 18,152
Buildings	127,201
Tenant improvements	1,349
Building and land improvements	11,235
Construction in progress	2,032
Other assets	1,049
Total purchase price	185,363
In-place leases
Allocation of the consideration paid for the acquired assets and liabilities
Deferred leasing intangibles	$ (16,743)
Weighted average amortization period of lease intangibles	7 years 10 months 20 days
Tenant relationships
Allocation of the consideration paid for the acquired assets and liabilities
Deferred leasing intangibles	$ (8,404)
Weighted average amortization period of lease intangibles	11 years 3 months 10 days
Above market leases
Allocation of the consideration paid for the acquired assets and liabilities
Deferred leasing intangibles	$ (327)
Weighted average amortization period of lease intangibles	4 years 3 months 25 days
Below market leases
Allocation of the consideration paid for the acquired assets and liabilities
Deferred leasing intangibles	$ 1,129
Weighted average amortization period of lease intangibles	8 years 5 months 15 days

Rental Property - Acquisition_3

Rental Property - Acquisitions - Results of Operations (Details) - Acquisitions 2019 [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)
Business Acquisition [Line Items]
Revenue	$ 1,194
Net income (loss)	$ 145

Rental Property - Disposals (De

Rental Property - Disposals (Details) $ in Thousands, ft² in Millions	3 Months Ended
	Mar. 31, 2019USD ($)ft²building	Mar. 31, 2018USD ($)	Dec. 31, 2018USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings disposed | building	395
Area (in square feet) | ft²	78.2
Carrying value of property sold	$ 3,118,516		$ 2,991,701
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of buildings disposed | building	5
Area (in square feet) | ft²	1
Carrying value of property sold	$ 15,300
Contribution to revenue	100	$ 1,100
Disposal Group, Including Discontinued Operation, Operating Income (Loss)	(200)	$ 500
Net proceeds from sales of rental property	16,600
Gain (Loss) on Sale	$ 1,300

Rental Property - Loss on Impai

Rental Property - Loss on Impairments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)buildingRate
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment of Real Estate | $	$ 5,344
Fair Value, Inputs, Level 3 [Member] | Income Approach Valuation Technique
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Property, Plant, and Equipment, Fair Value Disclosure | $	$ 4,373
Fair Value Inputs, Discount Rates | Rate	12.00%
Fair Value Inputs Exit Capitalization Rate | Rate	12.00%
Rapid City, SD, Q4 2007
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Buildings Impaired | building	1

Rental Property - Deferred Leas

Rental Property - Deferred Leasing Intangibles (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Deferred leasing intangibles, gross	$ 573,179		$ 588,517
Deferred leasing intangibles assets, accumulated amortization	(224,740)		(246,502)
Deferred leasing intangibles, net	348,439		342,015
Below market lease, gross	30,862		34,331
Below market lease, accumulated amortization	(10,394)		(12,764)
Below market lease, net	20,468		21,567
Net decrease to rental income related to above and below market lease amortization	967	$ 1,207
Above market leases
Finite-Lived Intangible Assets [Line Items]
Deferred leasing intangibles, gross	70,961		73,122
Deferred leasing intangibles assets, accumulated amortization	(30,409)		(31,059)
Deferred leasing intangibles, net	40,552		42,063
Other intangible lease assets
Finite-Lived Intangible Assets [Line Items]
Deferred leasing intangibles, gross	502,218		515,395
Deferred leasing intangibles assets, accumulated amortization	(194,331)		(215,443)
Deferred leasing intangibles, net	307,887		$ 299,952
Amortization expense related to other intangible lease assets	16,814	$ 18,100
Estimated Net Amortization of In-Place Leases, Leasing Commissions and Tenant Relationships
Remainder of 2019	48,278
2020	54,265
2021	43,369
2022	35,017
2023	28,732
Net decrease to rental income related to above and below market lease amortization
Estimated Net Amortization of In-Place Leases, Leasing Commissions and Tenant Relationships
Remainder of 2019	2,900
2020	3,546
2021	2,221
2022	1,361
2023	$ 1,363

Debt - Summary (Details)

Debt - Summary (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,347,030	$ 1,332,511
Unamortized debt issuance costs	(6,240)	(6,653)
Unamortized fair market value premium	48	50
Principal outstanding	$ 1,340,838	1,325,908
Weighted average interest rate	3.56%
Debt Instrument, Unused Borrowing Capacity, Amount	$ 553,900
Interest Rate Swaps
Debt Instrument [Line Items]
Notional amount	$ 600,000
London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Stated interest rate	2.4945%
$175 Million Unsecured Term Loan E [Member]
Debt Instrument [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount	$ 175,000
Unsecured Credit Facility
Debt Instrument [Line Items]
Principal outstanding	115,500	$ 100,500
Maximum borrowing capacity	$ 500,000
Unsecured Credit Facility | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate	0.90%	0.90%
Unsecured Credit Facility | Prepaid Expenses and Other Assets
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ (3,000)	$ (3,200)
Unsecured Term Loans
Debt Instrument [Line Items]
Long-term debt, gross	600,000	600,000
Unamortized debt issuance costs	(3,358)	(3,640)
Principal outstanding	596,642	596,360
Unsecured Term Loans | $150 Million Wells Fargo Unsecured Term Loan C
Debt Instrument [Line Items]
Long-term debt, gross	$ 150,000	$ 150,000
Stated interest rate	2.39%
Fixed Interest Rate (as a percent)	1.39%
Unsecured Term Loans | $150 Million Wells Fargo Unsecured Term Loan C | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.00%
Unsecured Term Loans | $150 Million Wells Fargo Unsecured Term Loan B
Debt Instrument [Line Items]
Long-term debt, gross	$ 150,000	$ 150,000
Stated interest rate	3.05%
Fixed Interest Rate (as a percent)	2.05%
Unsecured Term Loans | $150 Million Wells Fargo Unsecured Term Loan B | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.00%
Unsecured Term Loans | $150 Million Wells Fargo Unsecured Term Loan A
Debt Instrument [Line Items]
Long-term debt, gross	$ 150,000	$ 150,000
Stated interest rate	2.70%
Fixed Interest Rate (as a percent)	1.70%
Unsecured Term Loans | $150 Million Wells Fargo Unsecured Term Loan A | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.00%
Unsecured Term Loans | $150 Million Unsecured Term Loan D [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 150,000	$ 150,000
Stated interest rate	2.85%
Fixed Interest Rate (as a percent)	1.85%
Unsecured Term Loans | $150 Million Unsecured Term Loan D [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.00%
Unsecured Term Loans | $175 Million Unsecured Term Loan E [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 0	$ 0
Stated interest rate	3.92%
Fixed Interest Rate (as a percent)	2.92%
Unsecured Term Loans | $175 Million Unsecured Term Loan E [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument [Line Items]
Debt Instrument, Basis Spread on Variable Rate		1.00%
Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 575,000	$ 575,000
Unamortized debt issuance costs	(2,413)	(2,512)
Principal outstanding	572,587	572,488
Unsecured Notes | $100 Million Series F Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 100,000	100,000
Stated interest rate	3.98%
Unsecured Notes | $50 Million Series A Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 50,000	50,000
Stated interest rate	4.98%
Unsecured Notes | $100 Million Series D Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 100,000	100,000
Stated interest rate	4.32%
Unsecured Notes | $75 Million Series G Unsecured Notes [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 75,000	75,000
Stated interest rate	4.10%
Unsecured Notes | $50 Million Series B Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 50,000	50,000
Stated interest rate	4.98%
Unsecured Notes | $80 Million Series C Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 80,000	80,000
Stated interest rate	4.42%
Unsecured Notes | $20 Million Series E Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	$ 20,000	20,000
Stated interest rate	4.42%
Unsecured Notes | $100 Million Series H Unsecured Notes [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 100,000	100,000
Stated interest rate	4.27%
Mortgage Loans Payable
Debt Instrument [Line Items]
Long-term debt, gross	$ 56,530	57,011
Unamortized debt issuance costs	(469)	(501)
Unamortized fair market value premium	48	50
Principal outstanding	56,109	56,560
Mortgage Loans Payable | Wells Fargo Bank, National Association CMBS Loan
Debt Instrument [Line Items]
Long-term debt, gross	$ 52,763	53,216
Stated interest rate	4.31%
Penalty free prepayment period	3 months
Mortgage Loans Payable | Thrivent Financial for Lutherans Due December 15, 2023 [Member]
Debt Instrument [Line Items]
Long-term debt, gross	$ 3,767	$ 3,795
Stated interest rate	4.78%
Penalty free prepayment period	3 months

Debt - 2019 Activity (Details)

Debt - 2019 Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Debt Instrument [Line Items]
Debt Instrument, Unused Borrowing Capacity, Amount	$ 553,900
Net book value of properties that are collateral for debt arrangements	87,200		$ 88,200
Accounts Payable and Accrued Liabilities [Member]
Debt Instrument [Line Items]
Interest payable	7,700		$ 5,900
Interest Expense [Member]
Debt Instrument [Line Items]
Amortization of deferred financing fees	618	$ 534
Line of Credit Facility, Commitment Fee Amount	$ 383	$ 339

Debt - Fair Value (Details)

Debt - Fair Value (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Long-term debt, gross	$ 1,347,030	$ 1,332,511
Unamortized fair market value premium	48	50
Unamortized debt issuance costs	(6,240)	(6,653)
Principal outstanding	1,340,838	1,325,908
Long-term debt, fair value	1,369,827	1,343,081
Unsecured Credit Facility
Debt Instrument [Line Items]
Principal outstanding	115,500	100,500
Long-term debt, fair value	115,500	100,500
Unsecured Term Loans
Debt Instrument [Line Items]
Long-term debt, gross	600,000	600,000
Unamortized debt issuance costs	(3,358)	(3,640)
Principal outstanding	596,642	596,360
Long-term debt, fair value	600,000	600,000
Unsecured Notes
Debt Instrument [Line Items]
Long-term debt, gross	575,000	575,000
Unamortized debt issuance costs	(2,413)	(2,512)
Principal outstanding	572,587	572,488
Long-term debt, fair value	596,833	585,292
Mortgage Loans Payable
Debt Instrument [Line Items]
Long-term debt, gross	56,530	57,011
Unamortized fair market value premium	48	50
Unamortized debt issuance costs	(469)	(501)
Principal outstanding	56,109	56,560
Long-term debt, fair value	$ 57,494	$ 57,289

Use of Derivative Financial I_3

Use of Derivative Financial Instruments - Risk Management and Unsecured Loan Swaps (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Interest Rate Swaps
Unsecured Term Loan Swaps
Notional amount assets	$ 600,000	$ 600,000
Notional amount liabilities	300,000	$ 300,000
Interest Rate Derivative, Regions Bank, March 01, 2013
Unsecured Term Loan Swaps
Notional amount assets	25,000
Derivative Asset, Fair Value, Gross Asset	$ 235
Fixed Interest Rate (as a percent)	1.33%
Interest Rate Derivative, Capital One, July 01, 2013
Unsecured Term Loan Swaps
Notional amount assets	$ 50,000
Derivative Asset, Fair Value, Gross Asset	$ 316
Fixed Interest Rate (as a percent)	1.681%
Interest Rate Derivative, Capital One, August 01, 2013
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 153
Fixed Interest Rate (as a percent)	1.703%
Interest Rate Derivative, Regions Bank, February 03, 2014
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 90
Fixed Interest Rate (as a percent)	1.9925%
Interest Rate Derivative, The Toronto-Dominion Bank, September 29, 2016
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 342
Fixed Interest Rate (as a percent)	1.383%
Interest Rate Derivative, PNC Bank, September 29, 2016
Unsecured Term Loan Swaps
Notional amount assets	$ 50,000
Derivative Asset, Fair Value, Gross Asset	$ 678
Fixed Interest Rate (as a percent)	1.3906%
Interest Rate Derivative, Regions Bank, September 29, 2016
Unsecured Term Loan Swaps
Notional amount assets	$ 35,000
Derivative Asset, Fair Value, Gross Asset	$ 477
Fixed Interest Rate (as a percent)	1.3858%
Interest Rate Derivative, US Bank, September 29, 2016
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 338
Fixed Interest Rate (as a percent)	1.395%
Interest Rate Derivative, Capital One, September 29, 2016
Unsecured Term Loan Swaps
Notional amount assets	$ 15,000
Derivative Asset, Fair Value, Gross Asset	$ 202
Fixed Interest Rate (as a percent)	1.395%
Interest Rate Derivative, Royal Bank of Canada, March 20, 2015
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 256
Fixed Interest Rate (as a percent)	1.709%
Interest Rate Derivative, The Toronto-Dominion Bank, March 20, 2015
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 255
Fixed Interest Rate (as a percent)	1.7105%
Interest Rate Derivative, The Toronto-Dominion Bank, September 10, 2017
Unsecured Term Loan Swaps
Notional amount assets	$ 100,000
Derivative Asset, Fair Value, Gross Asset	$ 18
Fixed Interest Rate (as a percent)	2.2255%
Interest Rate Derivative, Wells Fargo Bank, March 20, 2015
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 243
Fixed Interest Rate (as a percent)	1.828%
Interest Rate Derivative, The Toronto-Dominion Bank, February 14, 2020
Unsecured Term Loan Swaps
Notional amount liabilities	$ 25,000
Derivative Liability, Fair Value, Gross Liability	$ (204)
Fixed Interest Rate (as a percent)	2.4535%
Interest Rate Derivative, Regions Bank, February 14, 2020
Unsecured Term Loan Swaps
Notional amount liabilities	$ 50,000
Derivative Liability, Fair Value, Gross Liability	$ (430)
Fixed Interest Rate (as a percent)	2.475%
Interest Rate Derivative, Capital One, February 14, 2020
Unsecured Term Loan Swaps
Notional amount liabilities	$ 50,000
Derivative Liability, Fair Value, Gross Liability	$ (487)
Fixed Interest Rate (as a percent)	2.53%
Interest Rate Derivative, The Toronto-Dominion Bank, October 30, 2017
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 269
Fixed Interest Rate (as a percent)	1.8485%
Interest Rate Derivative, Royal Bank of Canada, October 30, 2017
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 267
Fixed Interest Rate (as a percent)	1.8505%
Interest Rate Derivative, Wells Fargo Bank, October 30, 2017
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 267
Fixed Interest Rate (as a percent)	1.8505%
Interest Rate Derivative, PNC Bank, $25m, October 30, 2017
Unsecured Term Loan Swaps
Notional amount assets	$ 25,000
Derivative Asset, Fair Value, Gross Asset	$ 269
Fixed Interest Rate (as a percent)	1.8485%
Interest Rate Derivative, PNC Bank, $50m, October 30, 2017
Unsecured Term Loan Swaps
Notional amount assets	$ 50,000
Derivative Asset, Fair Value, Gross Asset	$ 539
Fixed Interest Rate (as a percent)	1.8475%
Interest Rate Derivative, The Toronto-Dominion Bank, July 26, 2019 [Member]
Unsecured Term Loan Swaps
Notional amount liabilities	$ 50,000
Derivative Liability, Fair Value, Gross Liability	$ (1,696)
Fixed Interest Rate (as a percent)	2.918%
Interest Rate Derivative, PNC Bank, July 26, 2019 [Member]
Unsecured Term Loan Swaps
Notional amount liabilities	$ 50,000
Derivative Liability, Fair Value, Gross Liability	$ (1,699)
Fixed Interest Rate (as a percent)	2.919%
Interest Rate Derivative, Bank of Montreal, July 26, 2019 [Member]
Unsecured Term Loan Swaps
Notional amount liabilities	$ 50,000
Derivative Liability, Fair Value, Gross Liability	$ (1,696)
Fixed Interest Rate (as a percent)	2.919%
Interest Rate Derivative, US Bank, July 26, 2019 [Member]
Unsecured Term Loan Swaps
Notional amount liabilities	$ 25,000
Derivative Liability, Fair Value, Gross Liability	$ (848)
Fixed Interest Rate (as a percent)	2.919%

Use of Derivative Financial I_4

Use of Derivative Financial Instruments - FV of Interest Rate Swaps (Details) - Interest Rate Swaps - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Fair value of the interest rate swaps outstanding
Notional amount assets	$ 600,000	$ 600,000
Fair value - assets	5,214	9,151
Notional amount liabilities	300,000	300,000
Fair Value - liabilities	$ (7,060)	$ (4,011)

Use of Derivative Financial I_5

Use of Derivative Financial Instruments - Cash Flow Hedges and Contingent Features (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash Flow Hedges of Interest Rate Risk
Total interest expense presented in the Consolidated Statements of Operations in which the effects of cash flow hedges are recorded	$ 12,834	$ 11,392
Interest Rate Swaps
Cash Flow Hedges of Interest Rate Risk
Additional amount reclassified from accumulated other comprehensive income (loss) as a decrease to interest expense over the next twelve months	(3,000)
Income (loss) recognized in accumulated other comprehensive income (loss) on interest rate swaps	(5,856)	7,493
Income (loss) reclassified from accumulated other comprehensive income into income (loss) as interest expense	1,122	(230)
Total interest expense presented in the Consolidated Statements of Operations in which the effects of cash flow hedges are recorded	12,834	$ 11,392
Assets Needed for Immediate Settlement, Aggregate Fair Value	$ 3,500

Use of Derivative Financial I_6

Use of Derivative Financial Instruments - FV on Recurring Basis (Details) - Interest Rate Swaps - Fair value on recurring basis - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Assets (liabilities):
Interest rate swaps-Asset	$ 5,214	$ 9,151
Interest rate swaps-Liability	(7,060)	(4,011)
Level 1
Assets (liabilities):
Interest rate swaps-Asset	0	0
Interest rate swaps-Liability	0	0
Level 2
Assets (liabilities):
Interest rate swaps-Asset	5,214	9,151
Interest rate swaps-Liability	(7,060)	(4,011)
Level 3
Assets (liabilities):
Interest rate swaps-Asset	0	0
Interest rate swaps-Liability	$ 0	$ 0

Equity - Preferred Stock (Detai

Equity - Preferred Stock (Details) - $ / shares	Apr. 09, 2019	Jun. 11, 2018	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Jul. 11, 2018
Series C Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares issued			3,000,000	3,000,000				3,000,000
Preferred stock, liquidation preference (in dollars per share)			$ 25	$ 25				$ 25
Dividend rate (as a percent)			6.875%
Preferred Stock, Dividends Per Share, Declared			$ 0.4296875	$ 0.4296875	$ 0.4296875	$ 0.4296875	$ 0.4296875	1.7187500
Dividends Payable, Date Declared			Jan. 10, 2019	Oct. 10, 2018	Jul. 11, 2018	Apr. 10, 2018	Feb. 14, 2018
Dividends Payable, Date to be Paid			Apr. 1, 2019	Dec. 31, 2018	Oct. 1, 2018	Jul. 2, 2018	Apr. 2, 2018
Series C Preferred Stock | Scenario, Forecast [Member]
Class of Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared	$ 0.4296875
Series B Preferred Stock
Class of Stock [Line Items]
Preferred Stock, Dividends Per Share, Declared				$ 0	$ 0.0460069	$ 0.4140625	$ 0.4140625	$ 0.8741319
Dividends Payable, Date Declared					Jul. 11, 2018	Apr. 10, 2018	Feb. 14, 2018
Dividends Payable, Date to be Paid					Oct. 1, 2018	Jul. 2, 2018	Apr. 2, 2018
Stock Redeemed or Called During Period, Shares		2,800,000
Preferred Stock, Redemption Price Per Share									$ 25

Equity - Common Stock ATM (Deta

Equity - Common Stock ATM (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Class of Stock [Line Items]
Proceeds from sales of common stock	$ 150,189	$ 0
At The Market Program 2019 $600 Million | Common Stock
Class of Stock [Line Items]
Common Stock Value Authorized under Stock Offering Program	600,000
Aggregate value of common stock available to be sold under the ATM	$ 449,811
Number of shares sold	5,441,409
Proceeds from sales of common stock	$ 150,189
Sales agents' fee	1,302
Net proceeds	$ 148,887
At The Market Program 2017 $500 Million | Common Stock
Class of Stock [Line Items]
Number of shares sold			14,724,614
Proceeds from sales of common stock			$ 390,447
Sales agents' fee			4,040
Net proceeds			$ 386,407
At The Market (ATM) Program | Common Stock
Class of Stock [Line Items]
Number of shares sold	5,441,409		14,724,614
Proceeds from sales of common stock	$ 150,189		$ 390,447
Sales agents' fee	1,302		4,040
Net proceeds	$ 148,887		$ 386,407
Weighted Average | At The Market Program 2019 $600 Million | Common Stock
Class of Stock [Line Items]
Issue price (in dollars per share)	$ 27.60
Weighted Average | At The Market Program 2017 $500 Million | Common Stock
Class of Stock [Line Items]
Issue price (in dollars per share)			$ 26.52
Weighted Average | At The Market (ATM) Program | Common Stock
Class of Stock [Line Items]
Issue price (in dollars per share)	$ 27.60		$ 26.52

Equity - Common Stock Dividends

Equity - Common Stock Dividends (Details) - Common Stock - $ / shares	Apr. 15, 2019	Apr. 09, 2019	Mar. 15, 2019	Feb. 15, 2019	Jan. 15, 2019	Jan. 10, 2019	Dec. 17, 2018	Nov. 15, 2018	Oct. 15, 2018	Oct. 10, 2018	Sep. 17, 2018	Aug. 15, 2018	Jul. 16, 2018	Jul. 11, 2018	Jun. 15, 2018	May 15, 2018	Apr. 16, 2018	Apr. 10, 2018	Mar. 15, 2018	Feb. 15, 2018	Nov. 02, 2017	Mar. 31, 2019	Dec. 31, 2018
Class of Stock [Line Items]
Common Stock, Dividends, Per Share, Cash Paid			$ 0.119167	$ 0.119167	$ 0.118333		$ 0.118333	$ 0.118333	$ 0.118333		$ 0.118333	$ 0.118333	$ 0.118333		$ 0.118333	$ 0.118333	$ 0.118333		$ 0.118333	$ 0.118333		$ 0.357501	$ 1.419996
Common Stock, Dividends, Per Share, Declared						$ 0.119167				$ 0.118333				$ 0.118333				$ 0.118333			$ 0.118333	$ 0.357501	$ 1.419996
Scenario, Forecast [Member]
Class of Stock [Line Items]
Common Stock, Dividends, Per Share, Cash Paid	$ 0.119167
Common Stock, Dividends, Per Share, Declared		$ 0.119167

Equity - Restricted Stock (Deta

Equity - Restricted Stock (Details) - Restricted stock - USD ($) $ / shares in Units, $ in Thousands	Jan. 07, 2019	Jan. 05, 2018	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	4 years
Shares
Unvested at beginning of period (in shares)			190,462	237,207	237,207
Granted (in shares)			110,830		76,659
Vested (in shares)			(78,431)	(112,405)	(112,405)
Forfeited (in shares)			(2,320)		(10,999)
Unvested at end of period (in shares)			220,541		190,462
Fair value of restricted stock per share at grant date	$ 24.85	$ 26.40
Stock Repurchased and Retired During Period, Shares			58,697		41,975
Unrecognized compensation costs			$ 4,400
Unrecognized compensation costs, period for recognition			2 years 10 months 20 days
Vested (in shares)			(78,431)	(112,405)	(112,405)
Fair value of shares vested			$ 1,951	$ 3,002

Noncontrolling Interest - Summa

Noncontrolling Interest - Summary (Details) - shares	3 Months Ended	12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Noncontrolling interest
Noncontrolling interest ownership percentage	3.30%	3.50%	4.10%
Noncontrolling Interest - Unit holders in Operating Partnership
Noncontrolling interest
Units outstanding, balance at beginning of period (in units)	4,069,434	4,096,687
Granted/Issued	364,173	324,802
Forfeited	10,208	0
Conversions from LTIP units to Other Common Units	0	0
Redemptions from Other Common Units to common stock	439,071	352,055
Units outstanding, balance at end of period (in units)	3,984,328	4,069,434
LTIP Units | Noncontrolling Interest - Unit holders in Operating Partnership
Noncontrolling interest
Units outstanding, balance at beginning of period (in units)	1,616,200	1,457,070
Granted/Issued	364,173	324,802
Forfeited	10,208	0
Conversions from LTIP units to Other Common Units	202,173	165,672
Redemptions from Other Common Units to common stock	0	0
Units outstanding, balance at end of period (in units)	1,767,992	1,616,200
Other Common Units | Noncontrolling Interest - Unit holders in Operating Partnership
Noncontrolling interest
Units outstanding, balance at beginning of period (in units)	2,453,234	2,639,617
Granted/Issued	0	0
Forfeited	0	0
Conversions from LTIP units to Other Common Units	(202,173)	(165,672)
Redemptions from Other Common Units to common stock	439,071	352,055
Units outstanding, balance at end of period (in units)	2,216,336	2,453,234

Noncontrolling Interest - LTIP

Noncontrolling Interest - LTIP FV Assumptions (Details) - LTIP Units - USD ($) $ / shares in Units, $ in Thousands	Jan. 07, 2019	Mar. 31, 2019	Dec. 31, 2018
Assumptions
Expected term (years)	10 years
Expected volatility	19.00%
Expected dividend yield	6.00%
Risk-free interest rate	2.57%
Fair value of LTIP units at issuance (in thousands)	$ 3,636
LTIP units at issuance	154,649	364,173	324,802
Fair value unit price per LTIP unit at issuance	$ 23.51
Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	4 years
Independent Director | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year

Noncontrolling Interest - LTI_2

Noncontrolling Interest - LTIP Units (Details) - LTIP Units - USD ($) $ in Thousands	Jan. 07, 2019	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Units
Unvested at beginning of period (in shares)		251,216	300,307	300,307
Granted	154,649	364,173		324,802
Vested (in units)		(157,689)	(231,041)	(373,893)
Forfeited (in units)		(10,208)		0
Unvested at end of period (in shares)		447,492		251,216
Unrecognized compensation costs		$ 7,300
Unrecognized compensation costs, period for recognition		2 years 6 months 20 days
Vested (in units)		157,689	231,041	373,893
Fair value of units vested		$ 4,063	$ 6,035

Equity Incentive Plan - Perform

Equity Incentive Plan - Performance Plan Assumptions (Details) - Performance shares $ in Thousands	Jan. 07, 2019USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility	20.70%
Expected dividend yield	6.00%
Risk-free interest rate	2.56%
Fair value of performance units grant (in thousands)	$ 5,620

Equity Incentive Plan - 2019 Ac

Equity Incentive Plan - 2019 Activity (Details) - USD ($) $ in Millions	Jan. 07, 2019	Dec. 31, 2018	Mar. 31, 2019	Dec. 31, 2018
LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted	154,649		364,173	324,802
Unrecognized compensation costs			$ 7.3
Unrecognized compensation costs, period for recognition			2 years 6 months 20 days
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	4 years
Stock Repurchased and Retired During Period, Shares			58,697	41,975
Granted			110,830	76,659
Unrecognized compensation costs			$ 4.4
Unrecognized compensation costs, period for recognition			2 years 10 months 20 days
Performance shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation costs			$ 9.2
Unrecognized compensation costs, period for recognition			2 years 4 months 20 days
Performance Units Granted in 2016 [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)		3 years
Performance Units Granted in 2016 [Member] | LTIP Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year
Issuance of vested LTIP units and shares	102,216
Granted	107,308
Performance Units Granted in 2016 [Member] | Common Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of vested LTIP units and shares	74,032
Stock Repurchased and Retired During Period, Shares	30,193
Performance Units Granted in 2016 [Member] | Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period (in years)	1 year
Granted	22,678

Equity Incentive Plan - Equity

Equity Incentive Plan - Equity Non-cash Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
General and Administrative Expenses
Equity Incentive Plan
Share-based compensation	$ 2,278	$ 2,220
Restricted stock | General and Administrative Expenses
Equity Incentive Plan
Share-based compensation	427	434
LTIP Units | General and Administrative Expenses
Equity Incentive Plan
Share-based compensation	887	871
Performance shares | General and Administrative Expenses
Equity Incentive Plan
Share-based compensation	859	829
Independent Director | General and Administrative Expenses
Equity Incentive Plan
Share-based compensation	$ 105	$ 86
Common Stock | Independent Director
Equity Incentive Plan
Number of days of average trailing stock price used to calculate number of shares of common stock granted	10 days	10 days

Leases - Rental Income (Details

Leases - Rental Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Leases [Abstract]
Fixed lease payments	$ 72,117
Variable lease payments	22,181
Straight-line rental income	2,284
Net decrease to rental income related to above and below market lease amortization	(967)	$ (1,207)
Total rental income	$ 95,615	$ 83,127

Leases - Tenant Accounts Receiv

Leases - Tenant Accounts Receivable (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Lease Security Deposits Available in Letters of Credit	$ 18.4		$ 18.3
Lease security deposits in restricted cash	0.7		0.7
Lease security deposits included in tenant prepaid rent and security deposits on the Balance Sheet	8.7		8.4
Real Estate Taxes, Tenant Responsibility	3.9	$ 3.1
Accrued Income Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Deferred Rent Receivables, Net	$ 34.2		$ 32.4

Leases - Maturity of Fixed Leas

Leases - Maturity of Fixed Lease Payments (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Remainder of Fiscal Year	$ 240,185
2020	288,787
2021	243,992
2022	203,368
2023	165,946
Thereafter	$ 578,495
2019		$ 299,978
2020		271,936
2021		226,970
2022		188,707
2023		152,814
Thereafter		$ 535,192

Leases - Lessee Leases (Details

Leases - Lessee Leases (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019USD ($)Rate
Lessee, Lease, Description [Line Items]
Operating Lease, Weighted Average Remaining Lease Term	35 years 1 month
Operating Lease, Weighted Average Discount Rate, Percent | Rate	7.10%
Lease, Cost	$ 597
Operating Lease, Payments	$ 569
Minimum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	2 years
Lessee, Operating Lease, Renewal Term	10 years
Maximum [Member]
Lessee, Lease, Description [Line Items]
Lessee, Operating Lease, Term of Contract	47 years 9 months
Lessee, Operating Lease, Renewal Term	20 years
Operating Expense [Member]
Lessee, Lease, Description [Line Items]
Lease, Cost	$ 331
General and Administrative Expenses
Lessee, Lease, Description [Line Items]
Lease, Cost	$ 266

Leases - Maturity of Operating

Leases - Maturity of Operating Lease Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Leases [Abstract]
Remainder of Fiscal Year	$ 1,712
2020	2,294
2021	1,400
2022	1,107
2023	1,116
Thereafter	48,155
Lessee, Operating Lease, Liability, Payments, Due	55,784
Less: Imputed interest	(37,998)
Operating lease liabilities	$ 17,786	$ 0
2019		2,110
2020		2,122
2021		1,227
2022		935
2023		944
Thereafter		$ 45,580

Earnings Per Share (Details)

Earnings Per Share (Details) - shares	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Participating securities	213,856	201,650

Earnings Per Share - Reconcilia

Earnings Per Share - Reconciliation of Numerator and Denominator (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator
Net income	$ 7,389	$ 25,149
Less: preferred stock dividends	1,289	2,448
Less: amount allocated to participating securities	79	71
Less: income attributable to noncontrolling interest after preferred stock dividends	214	954
Net income attributable to common stockholders	$ 5,807	$ 21,676
Denominator
Weighted average common shares outstanding — basic	114,721	97,021
Share-based compensation	272	302
Weighted average common shares outstanding — diluted	114,993	97,323
Net income per share — basic and diluted
Net income per share attributable to common stockholders — basic	$ 0.05	$ 0.22
Net income per share attributable to common stockholders — diluted	$ 0.05	$ 0.22
Restricted stock
Net income per share — basic and diluted
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	214	202

Commitments and Contingencies -

Commitments and Contingencies - Agreements (Details) $ in Millions	Mar. 31, 2019USD ($)
Commitments and Contingencies Disclosure [Abstract]
Letters of credit outstanding	$ 5.6
Contractual Obligation	$ 9.8

Subsequent Events - Underwritte

Subsequent Events - Underwritten Public Offering (Details) - USD ($) $ / shares in Units, $ in Thousands	Apr. 04, 2019	Apr. 01, 2019	Mar. 31, 2019	Mar. 31, 2018
Class of Stock [Line Items]
Proceeds from sales of common stock			$ 150,189	$ 0
Subsequent Event | Common Stock
Class of Stock [Line Items]
Sale of Stock, Number of Shares Issued in Transaction		7,475,000
Shares Issued, Price Per Share		$ 28.72
Proceeds from sales of common stock	$ 214,700
Subsequent Event | Over-Allotment Option [Member] | Common Stock
Class of Stock [Line Items]
Sale of Stock, Number of Shares Issued in Transaction		975,000

Subsequent Events - Authorized

Subsequent Events - Authorized Shares (Details) - shares	Apr. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Subsequent Event [Line Items]
Common stock, shares authorized		150,000,000	150,000,000
Preferred stock, shares authorized		15,000,000	15,000,000
Subsequent Event
Subsequent Event [Line Items]
Common stock, shares authorized	300,000,000
Preferred stock, shares authorized	20,000,000