Healthcare Realty Trust 10-K 12 Feb 20 2019 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2019	Feb. 07, 2020	Jun. 28, 2019
Cover page.
Document Type	10-K
Document Annual Report	true
Entity File Number	001-11852
Entity Registrant Name	HEALTHCARE REALTY TRUST INCORPORATED
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	62-1507028
Entity Address, Address Line One	3310 West End Avenue
Entity Address, Address Line Two	Suite 700
Entity Address, City or Town	Nashville
Entity Address, State or Province	TN
Entity Address, Postal Zip Code	37203
City Area Code	615
Local Phone Number	269-8175
Title of 12(b) Security	Common stock, $0.01 par value per share
Trading Symbol	HR
Security Exchange Name	NYSE
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Document Transition Report	false
Entity Central Index Key	0000899749
Document Period End Date	Dec. 31, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 3,953,733,413
Entity Common Stock, Shares Outstanding		134,703,119
Documents Incorporated by Reference	Portions of the Registrant’s definitive Proxy Statement relating to the Annual Meeting of Stockholders to be held on May 12, 2020 are incorporated by reference into Part III of this Report.

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Real estate properties
Land	$ 289,751	$ 230,206
Buildings, improvements and lease intangibles	3,986,326	3,675,415
Personal property	10,538	10,696
Construction in progress	48,731	33,107
Land held for development	24,647	24,647
Total real estate properties	4,359,993	3,974,071
Less accumulated depreciation	(1,121,102)	(1,015,174)
Total real estate properties, net	3,238,891	2,958,897
Cash and cash equivalents	657	8,381
Assets held for sale, net	37	9,272
Operating lease right-of-use assets	126,177
Financing lease right-of-use assets	12,667
Other assets, net	185,426	214,697
Total assets	3,563,855	3,191,247
Liabilities
Notes and bonds payable	1,414,069	1,345,984
Accounts payable and accrued liabilities	78,517	80,411
Liabilities of properties held for sale	145	587
Operating lease liabilities	91,574
Financing lease liabilities	18,037
Other liabilities	61,504	47,623
Total liabilities	1,663,846	1,474,605
Commitments and contingencies
Stockholders' equity
Preferred stock, $.01 par value; 50,000 shares authorized; none issued and outstanding	0	0
Common stock, $.01 par value; 300,000 shares authorized; 134,706 and 125,279 shares issued and outstanding at December 31, 2019 and 2018, respectively.	1,347	1,253
Additional paid-in capital	3,485,003	3,180,284
Accumulated other comprehensive loss	(6,175)	(902)
Cumulative net income attributable to common stockholders	1,127,304	1,088,119
Cumulative dividends	(2,707,470)	(2,552,112)
Total stockholders’ equity	1,900,009	1,716,642
Total liabilities and stockholders' equity	$ 3,563,855	$ 3,191,247

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Preferred stock, par value (in USD per share)	$ 0.01	$ 0.01
Preferred stock, authorized shares	50,000,000	50,000,000
Preferred stock, issued shares	0	0
Preferred stock, outstanding shares (shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized shares (shares)	300,000,000	300,000,000
Common stock, issued shares	134,706,000	125,279,000
Common stock, outstanding shares (shares)	134,706,000	125,279,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues
Rental income	$ 462,225
Rental income		$ 442,397	$ 416,978
Other operating	8,073	7,992	7,759
Total Revenue	470,298	450,389	424,737
Expenses
Property operating	180,005
Property operating		170,506	157,252
General and administrative	34,826	34,511	32,992
Acquisition and pursuit costs	1,742	738	2,180
Depreciation and amortization	177,859	164,201	142,472
Bad debt, net of recoveries		60	159
Total Expenses	394,432	370,016	335,055
Other income (expense)
Gain on sales of real estate assets	25,101	41,665	39,524
Interest expense	(55,435)	(52,804)	(56,402)
Loss on extinguishment of debt			(44,985)
Impairment of real estate assets	(5,617)		(5,385)
Interest and other income (expense), net	(730)	537	658
Total other income (expense)	(36,681)	(10,602)	(66,590)
Net income	$ 39,185	$ 69,771	$ 23,092
Basic earnings per common share (in USD per share)	$ 0.29	$ 0.55	$ 0.18
Diluted earnings per common share (in USD per share)	$ 0.29	$ 0.55	$ 0.18
Weighted average common shares outstanding - basic (in shares)	127,999,701	123,292,125	117,926,158
Weighted average common shares outstanding - diluted (in shares)	128,083,984	123,350,933	118,017,165

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 39,185	$ 69,771	$ 23,092
Other comprehensive income (loss)
Reclassification adjustment for losses included in net income (interest expense)	319	424	176
Losses arising during the period	(5,592)	(27)
Losses arising during the period			(74)
Other comprehensive income	(5,273)	397	102
Comprehensive income	$ 33,912	$ 70,168	$ 23,194

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Cumulative Net Income [Member]	Cumulative Dividends [Member]
Beginning Balance at Dec. 31, 2016	$ 1,653,414	$ 0	$ 1,164	$ 2,917,914	$ (1,401)	$ 995,256	$ (2,259,519)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock, net of costs	248,592		84	248,508
Common stock redemption	(3,018)		(1)	(3,017)
Share-based compensation	10,028		4	10,024
Net income	23,092					23,092
Gain on forward starting interest rate swaps	102				102
Dividends to common stockholders ($1.20 per share)	(142,327)						(142,327)
Ending Balance at Dec. 31, 2017	1,789,883	0	1,251	3,173,429	(1,299)	1,018,348	(2,401,846)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock, net of costs	616			616
Common stock redemption	(4,450)		(1)	(4,449)
Share-based compensation	10,691		3	10,688
Net income	69,771					69,771
Gain on forward starting interest rate swaps	397				397
Dividends to common stockholders ($1.20 per share)	(150,266)						(150,266)
Ending Balance at Dec. 31, 2018	1,716,642	0	1,253	3,180,284	(902)	1,088,119	(2,552,112)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock, net of costs	295,856		92	295,764
Common stock redemption	(3,318)		(1)	(3,317)
Share-based compensation	12,275		3	12,272
Net income	39,185					39,185
Loss on interest rate swaps	(5,273)				(5,273)
Dividends to common stockholders ($1.20 per share)	(155,358)						(155,358)
Ending Balance at Dec. 31, 2019	$ 1,900,009	$ 0	$ 1,347	$ 3,485,003	$ (6,175)	$ 1,127,304	$ (2,707,470)

Consolidated Statements of Eq_2

Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Stockholders' Equity [Abstract]
Dividend per share to common stockholders (in USD per share)	$ 1.20	$ 1.20	$ 1.20

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Cash Flows [Abstract]
Net income	$ 39,185	$ 69,771	$ 23,092
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	177,859	164,201	142,472
Other amortization	3,013	3,000	3,879
Share-based compensation	12,275	10,691	10,028
Amortization of straight-line rent receivable (lessor)	(3,000)	(4,281)	(6,072)
Amortization of straight-line rent on operating leases (lessee)	1,537	1,519	1,497
Gain on sales of real estate assets	(25,101)	(41,665)	(39,524)
Loss on extinguishment of debt			44,985
Impairment of real estate assets	5,617		5,385
Loss (income) from unconsolidated joint ventures	19	(4)	(7)
Distributions from unconsolidated joint ventures	381	182
Provision for bad debts, net		60	159
Changes in operating assets and liabilities:
Other assets, including right-of-use-assets	(8,573)	(3,998)	(2,156)
Accounts payable and accrued liabilities	2,752	4,731	(7,307)
Other liabilities	7,174	4,148	3,335
Net cash provided by operating activities	213,138	208,355	179,766
INVESTING ACTIVITIES
Acquisitions of real estate	(380,274)	(104,312)	(274,668)
Development of real estate	(25,985)	(26,728)	(14,911)
Additional long-lived assets	(64,670)	(70,807)	(80,613)
Investment in unconsolidated joint ventures			(8,701)
Proceeds from sales of real estate assets	52,401	96,812	119,426
Proceeds from notes receivable repayments		8	19
Net cash used in investing activities	(418,528)	(105,027)	(259,448)
FINANCING ACTIVITIES
Net borrowings on unsecured credit facility	31,000	73,000	82,000
Borrowings on term loan	50,000		0
Borrowings of notes and bonds payable			297,459
Repayments of notes and bonds payable	(13,857)	(19,850)	(5,829)
Redemption of notes and bonds payable			(442,774)
Dividends paid	(155,358)	(150,266)	(142,327)
Net proceeds from issuance of common stock	295,946	611	248,554
Common stock redemptions	(5,097)	(4,532)	(1,686)
Debt issuance and assumption costs	(4,589)	(125)	(4,007)
Payments made on finance leases	(379)		0
Net cash provided by (used in) financing activities	197,666	(101,162)	31,390
(Decrease) increase in cash and cash equivalents	(7,724)	2,166	(48,292)
Cash and cash equivalents at beginning of period	8,381	6,215	54,507
Cash and cash equivalents at end of period	657	8,381	6,215
Supplemental Cash Flow Information
Interest paid	53,978	45,752	64,395
Mortgage notes payable assumed upon acquisition (adjusted to fair value)		7,995	43,674
Invoices accrued for construction, tenant improvements and other capitalized costs	17,294	12,682	8,303
Capitalized interest	$ 1,411	$ 951	$ 871

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Business Overview Healthcare Realty Trust Incorporated (the “Company”) is a real estate investment trust ("REIT") that owns, leases, manages, acquires, finances, develops and redevelops income-producing real estate properties associated primarily with the delivery of outpatient healthcare services throughout the United States of America. The Company had gross investments of approximately $4.4 billion in 204 real estate properties, construction in progress, the Memphis Redevelopment, land held for development and corporate property as of December 31, 2019 . The Company’s 204 owned real estate properties are located in 25 states and total approximately 15.4 million square feet. The Company provided property management services to approximately 11.4 million square feet nationwide. Square footage and property count disclosures in these Notes to the Company's Consolidated Financial Statements are unaudited. Principles of Consolidation The Company’s Consolidated Financial Statements include the accounts of the Company, its wholly owned subsidiaries, joint ventures, and partnerships where the Company controls the operating activities. The Company's investments in its unconsolidated joint ventures are included in other assets and the related equity income is recognized within interest and other income (expense), net in other income (expense) on the Company's Consolidated Financial Statements. See Note 7 for additional information. All significant intercompany accounts, transactions and balances have been eliminated upon consolidation in the Consolidated Financial Statements. Use of Estimates in the Consolidated Financial Statements Preparation of the Consolidated Financial Statements in accordance with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect amounts reported in the Consolidated Financial Statements and accompanying notes. Actual results may differ from those estimates. Segment Reporting The Company owns, leases, acquires, manages, finances, develops and redevelops outpatient and other healthcare-related properties. The Company is managed as one reporting unit, rather than multiple reporting units, for internal reporting purposes and for internal decision-making. Therefore, the Company discloses its operating results in a single reportable segment. Real Estate Properties Real estate properties are recorded at cost or at fair value if acquired in a transaction that is a business combination under Accounting Standards Codification Topic 805, Business Combinations . Cost or fair value at the time of acquisition is allocated among land, buildings, tenant improvements, lease and other intangibles, and personal property as applicable. The Company’s gross real estate assets, on a financial reporting basis, totaled approximately $4.4 billion as of December 31, 2019 and $4.0 billion as of December 31, 2018 . During 2019 and 2018 , the Company eliminated against accumulated depreciation approximately $17.2 million and $9.9 million , respectively, of fully amortized real estate intangibles that were initially recorded as a component of certain real estate acquisitions. Also during 2019 and 2018 , approximately $1.3 million and $0.5 million of fully depreciated tenant and capital improvements that were no longer in service were eliminated against accumulated depreciation. Depreciation expense of real estate properties for the three years ended December 31, 2019, 2018 and 2017 was $152.6 million , $143.8 million and $129.4 million , respectively. Depreciation and amortization of real estate assets and liabilities in place as of December 31, 2019 , is provided for on a straight-line basis over the asset’s estimated useful life: Land improvements 3.0 to 39.0 years Buildings and improvements 3.3 to 39.0 years Lease intangibles (including ground lease intangibles) 2.1 to 99.0 years Personal property 2.8 to 20.0 years The Company capitalizes direct costs, including costs such as construction costs and professional services, and indirect costs, including capitalized interest and overhead costs, associated with the development and construction of real estate assets while substantive activities are ongoing to prepare the assets for their intended use. Capitalized interest cost is calculated using the weighted average interest rate of the Company's unsecured debt or the interest rate on project specific debt, if applicable. The Company continues to capitalize interest on the unoccupied portion of the properties in stabilization for up to one year after the buildings have been placed into service, at which time the capitalization of interest must cease. Land Held for Development Land held for development includes parcels of land owned by the Company, upon which the Company intends to develop and own outpatient healthcare facilities. The Company’s investment in seven parcels of land held for development located adjacent to certain of the Company's existing medical office buildings in Texas, Iowa, Tennessee and Colorado totaled approximately $24.6 million as of December 31, 2019 and December 31, 2018 . Asset Impairment The Company assesses the potential for impairment of identifiable, definite-lived, intangible assets and long-lived assets, including real estate properties, whenever events occur or a change in circumstances indicates that the carrying value might not be fully recoverable. Indicators of impairment may include significant underperformance of an asset relative to historical or expected operating results; significant changes in the Company’s use of assets or the strategy for its overall business; plans to sell an asset before its depreciable life has ended; the expiration of a significant portion of leases in a property; or significant negative economic trends or negative industry trends for the Company or its operators. In addition, the Company reviews for possible impairment, those assets subject to purchase options and those impacted by casualties, such as tornadoes and hurricanes. If management determines that the carrying value of the Company’s assets may not be fully recoverable based on the existence of any of the factors above, or others, management would measure and record an impairment charge based on the estimated fair value of the property or the estimated fair value less costs to sell the property. Acquisitions of Real Estate Properties with In-Place Leases The Company's acquisitions of real estate properties typically do not meet the definition of a business and are accounted for as asset acquisitions. Acquisitions of real estate properties with in-place leases are accounted for at relative fair value. When a building with in-place leases is acquired, the cost of the acquisition must be allocated between the tangible real estate assets "as-if-vacant" and the intangible real estate assets related to in-place leases based on their estimated fair values. Land fair value is estimated by using an assessment of comparable transactions and other relevant data. The values related to above- or below-market in-place lease intangibles are amortized over the remaining term of the leases upon acquisition to rental income where the Company is the lessor and to property operating expense where the Company is the lessee. The Company considers whether any of the in-place lease rental rates are above- or below-market. An asset (if the actual rental rate is above-market) or a liability (if the actual rental rate is below-market) is calculated and recorded in an amount equal to the present value of the future cash flows that represent the difference between the actual lease rate and the estimated market rate. If an in-place lease is identified as a below-market rental rate, the Company would also evaluate any renewal options associated with that lease to determine if the intangible should include those periods. The Company also estimates an absorption period, which can vary by property, assuming the building is vacant and must be leased up to the actual level of occupancy when acquired. During that absorption period, the owner would incur direct costs, such as tenant improvements, and would suffer lost rental income. Likewise, the owner would have acquired a measurable asset in that, assuming the building was vacant, certain fixed costs would be avoided because the actual in-place lessees would reimburse a certain portion of fixed costs through expense reimbursements during the absorption period. All of these intangible assets (above- or below-market lease, tenant improvement costs avoided, leasing costs avoided, rental income lost, and expenses recovered through in-place lessee reimbursements) are estimated and recorded in amounts equal to the present value of estimated future cash flows. The actual purchase price is allocated based on the various asset fair values described above. The building and tenant improvement components of the purchase price are depreciated over the estimated useful life of the building or the weighted average remaining term of the in-places leases. The at-market, in-place lease intangibles are amortized to amortization expense over the weighted average remaining term of the leases, customer relationship assets are amortized to amortization expense over terms applicable to each acquisition. Any goodwill recorded through a business combination would be reviewed for impairment at least annually and is not amortized. See Note 8 for more details on the Company’s intangible assets. Fair Value Measurements Fair value is defined as the price that would be received to sell an asset, or paid to transfer a liability, in an orderly transaction between market participants. In calculating fair value, a company must maximize the use of observable market inputs, minimize the use of unobservable market inputs and disclose in the form of an outlined hierarchy the details of such fair value measurements. A hierarchy of valuation techniques is defined to determine whether the inputs to a fair value measurement are considered to be observable or unobservable in a marketplace. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s market assumptions. This hierarchy requires the use of observable market data when available. These inputs have created the following fair value hierarchy: • Level 1 – quoted prices for identical instruments in active markets; • Level 2 – quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which significant inputs and significant value drivers are observable in active markets; and • Level 3 – fair value measurements derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. Executed purchase and sale agreements, that are binding agreements, are categorized as level one inputs. Brokerage estimates, letters of intent, or unexecuted purchase and sale agreements are considered to be level three as they are nonbinding in nature. Fair Value of Derivative Financial Instruments Derivative financial instruments are recorded at fair value on the Company's Consolidated Balance Sheets as other assets or other liabilities. The valuation of derivative instruments requires the Company to make estimates and judgments that affect the fair value of the instruments. Fair values of derivatives are estimated by pricing models that consider the forward yield curves and discount rates. The fair value of the Company's forward starting interest rate swap contracts are estimated by pricing models that consider foreign trade rates and discount rates. Such amounts and the recognition of such amounts are subject to significant estimates that may change in the future. For derivatives designated in qualifying cash flow hedging relationships, the change in fair value of the effective portion of the derivatives is recognized in accumulated other comprehensive income (loss). Gains and losses are reclassified from accumulated other comprehensive income (loss) into earnings once the underlying hedged transaction is recognized in earnings. As of December 31, 2019 and 2018, the Company had $6.2 million and $0.9 million , respectively, recorded in accumulated other comprehensive loss related to forward starting interest rate swaps entered into and settled during 2015 and a hedge of the Company's variable rate debt. See Note 10 for additional information. Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents includes short-term investments with original maturities of three months or less when purchased. Restricted cash includes cash held in escrow in connection with proceeds from the sales of certain real estate properties. The Company did not have any restricted cash for the year ended December 31, 2019. The Company had restricted cash during the year ended December 31, 2018, however it was reinvested for real estate acquisitions prior to the ending balance sheet date. Goodwill and Other Intangible Assets Goodwill and intangible assets with indefinite lives are not amortized, but are tested at least annually for impairment. Intangible assets with finite lives are amortized over their respective lives to their estimated residual values and are reviewed for impairment only when impairment indicators are present. Identifiable intangible assets of the Company are comprised of enterprise goodwill, in-place lease intangible assets, customer relationship intangible assets, and debt issuance costs. In-place lease and customer relationship intangible assets are amortized on a straight-line basis over the applicable lives of the assets. Debt issuance costs are amortized over the term of the debt instrument on the effective interest method or the straight-line method when the effective interest method is not applicable. Goodwill is not amortized but is evaluated annually as of December 31 for impairment. Both the 2019 and 2018 impairment evaluations indicated that no impairment had occurred with respect to the $3.5 million goodwill asset. See Note 8 for more detail on the Company’s intangible assets. Contingent Liabilities From time to time, the Company may be subject to loss contingencies arising from legal proceedings and similar matters. Additionally, while the Company maintains comprehensive liability and property insurance with respect to each of its properties, the Company may be exposed to unforeseen losses related to uninsured or underinsured damages. The Company continually monitors any matters that may present a contingent liability, and, on a quarterly basis, management reviews the Company’s reserves and accruals in relation to each of them, adjusting provisions as necessary in view of changes in available information. Liabilities for contingencies are first recorded when a loss is determined to be both probable and can be reasonably estimated. Changes in estimates regarding the exposure to a contingent loss are reflected as adjustments to the related liability in the periods when they occur. Because of uncertainties inherent in the estimation of contingent liabilities, it is possible that the Company’s provision for contingent losses could change materially in the near term. To the extent that any significant losses, in addition to amounts recognized, are at least reasonably possible, such amounts will be disclosed in the notes to the Consolidated Financial Statements. Share-Based Compensation The Company has various employee and director share-based awards outstanding. These awards include non-vested common stock and options to purchase common stock granted to employees pursuant to the 2015 Stock Incentive Plan and its predecessor plans (the “2015 Incentive Plan”) and the 2000 Employee Stock Purchase Plan (the “Employee Stock Purchase Plan”). The Company recognizes share-based payments to employees and directors in the Consolidated Statements of Income on a straight-line basis over the requisite service period based on the fair value of the award on the measurement date. See Note 12 for details on the Company’s share-based awards. Accumulated Other Comprehensive Income (Loss) Certain items must be included in comprehensive income, including items such as foreign currency translation adjustments, minimum pension liability adjustments, derivative instruments and unrealized gains or losses on available-for-sale securities. As of December 31, 2019, the Company’s accumulated other comprehensive income (loss) consists of the loss for changes in the fair value of active derivatives designated as cash flow hedges and the loss on the unamortized settlement of four forward starting swaps. See Note 10 for more details on the Company's derivative financial instruments. Revenue from Contracts with Customers (Topic 606) The Company recognizes certain revenue under the core principle of Topic 606. This requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Lease revenue is not within the scope of Topic 606. To achieve the core principle, the Company applies the five step model specified in the guidance. See the New Accounting Pronouncements section below for additional information. Revenue that is accounted for under Topic 606 is segregated on the Company’s Consolidated Statements of Income in the Other operating line item. This line item includes parking income, property lease guaranty income, management fee income and other miscellaneous income. Below is a detail of the amounts by category: YEAR ENDED DECEMBER 31, In thousands 2019 2018 2017 Type of Revenue Parking income $ 7,520 $ 6,930 $ 6,611 Property lease guaranty income 128 675 726 Management fee income 270 273 308 Miscellaneous 155 114 114 $ 8,073 $ 7,992 $ 7,759 The Company’s three major types of revenue that are accounted for under Topic 606 that are listed above are all accounted for as the performance obligation is satisfied. The performance obligations that are identified for each of these items are satisfied over time and the Company recognizes revenue monthly based on this principle. One of the Company’s owned real estate properties as of December 31, 2018 and 2017 respectively, was covered under property operating agreements between the Company and a sponsoring health system, which contractually obligate the sponsoring health system to provide to the Company a minimum return on the Company’s investment in the property in exchange for the right to be involved in the operating decisions of the property, including tenancy. The agreement expired February 28, 2019. If the minimum return was not achieved through normal operations of the property, the Company calculated and accrued to property lease guaranty revenue, each quarter, any shortfalls due from the sponsoring health systems under the terms of the property operating agreement. Management fee income for property management services provided to third parties are generally calculated, accrued and billed monthly based on a percentage of cash collections of tenant receivables for the month or a stated amount per square foot. Internal management fee income, where the Company manages its owned properties, is eliminated in consolidation. Rental Income Rental income related to non-cancelable operating leases is recognized as earned over the life of the lease agreements on a straight-line basis. The Company's lease agreements generally include provisions for stated annual increases or increases based on a Consumer Price Index ("CPI"). Rental income from properties under multi-tenant office lease arrangements and rental income from properties with single-tenant lease arrangements are included in rental income on the Company's Consolidated Statements of Income. The components of rental income are as follows: YEAR ENDED DECEMBER 31, (Dollars in thousands) 2019 2018 2017 Property operating income $ 415,142 $ 390,256 $ 358,009 Single-tenant net lease 44,083 47,860 52,897 Straight-line rent 3,000 4,281 6,072 Rental income $ 462,225 $ 442,397 $ 416,978 Federal Income Taxes No provision has been made for federal income taxes. The Company intends at all times to qualify as a REIT under Sections 856 through 860 of the Internal Revenue Code. The Company must distribute at least 90% per annum of its real estate investment trust taxable income to its stockholders and meet other requirements to continue to qualify as a real estate investment trust. See Note 15 for further discussion. The Company classifies interest and penalties related to uncertain tax positions, if any, in the Consolidated Financial Statements as a component of general and administrative expenses. No such amounts were recognized during the three years ended December 31, 2019. Federal tax returns for the years 2016, 2017 , 2018 and 2019 are currently subject to examination by taxing authorities. State Income Taxes The Company must pay certain state income taxes and the provisions for such taxes are generally included in general and administrative expense on the Company’s Consolidated Statements of Income. See Note 15 for further discussion. Sales and Use Taxes The Company must pay sales and use taxes to certain state tax authorities based on rents collected from tenants in properties located in those states. The Company is generally reimbursed for these taxes by the tenant. The Company accounts for the payments to the taxing authority and subsequent reimbursement from the tenant on a net basis in revenues in the Company’s Consolidated Statements of Income. Assets Held for Sale Long-lived assets held for sale are reported at the lower of their carrying amount or their fair value less estimated cost to sell. Further, depreciation of these assets ceases at the time the assets are classified as held for sale. Losses resulting from the sale of such properties are characterized as impairment losses in the Consolidated Statements of Income. See Note 5 for more detail on assets held for sale. Earnings per Share The Company uses the two-class method of computing net earnings per common share. Earnings per common share is calculated by considering share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents as participating securities. Undistributed earnings (excess net income over dividend payments) are allocated on a pro rata basis to common shareholders and restricted shareholders. Undistributed losses (dividends in excess of net income) do not get allocated to restricted stockholders as they do not have the contractual obligation to share in losses. The amount of undistributed losses that applies to the restricted stockholders is allocated to the common stockholders. Basic earnings per common share is calculated using weighted average shares outstanding less issued and outstanding non-vested shares of common stock. Diluted earnings per common share is calculated using weighted average shares outstanding plus the dilutive effect of the outstanding stock options from the Employee Stock Purchase Plan using the treasury stock method and the average stock price during the period. See Note 13 for the calculations of earnings per share. New Accounting Pronouncements Accounting Standards Update No. 2016-02, No. 2018-01 and No. 2018-11 In February 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-02, "Leases." In January 2018, the FASB issued ASU 2018-01, "Leases - Land Easement Practical Expedient for Transition to Topic 842," in July 2018, the FASB issued ASU 2018-10, "Codification Improvements to Topic 842, Leases" and ASU 2018-11, "Leases - Targeted Improvements," and in December 2018, the FASB issued ASU 2018-20, “Narrow-Scope Improvements for Lessors.” These accounting standard updates are collectively referred to as "Topic 842." Topic 842 provides several practical expedients that the Company elected. These are (a) the package of practical expedients offered that allows an entity not to reassess upon adoption (i) whether an expired or existing contract contains a lease, (ii) lease classification related to expired or existing lease arrangements, and (iii) whether costs incurred on expired or existing leases qualify as initial direct costs, (b) the lessor practical expedient not to separate certain non-lease components, such as common area maintenance, from the lease component if (i) the timing and pattern of transfer are the same for the non-lease component and associated lease component, and (ii) the lease component would be classified as an operating lease if accounted for separately and (c) the lessee practical expedient not to separate certain non-lease components from the associated lease component. For lessees, the new standard establishes a right-of-use ("ROU") model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases are classified as either finance or operating, with the classification affecting the pattern of expense recognition in the income statement. The Company's ground leases executed or assumed prior to the adoption of Topic 842 continue to be accounted for as operating leases and will not result in a materially different ground lease expense. However, each ground lease executed by the Company after the adoption of Topic 842 will be evaluated to determine if it is an operating or finance lease. If the lease is to be accounted for as a finance lease, ground lease expense would be accounted for using the effective interest method instead of the straight-line method over the term of the lease, which would result in higher ground lease expense in the earlier years of a ground lease when compared to the straight-line method. Leases in which the Company is the lessee are primarily ground leases, but also includes management office leases in third party buildings and certain copier and postage machine leases. The terms of the ground leases generally range from 40 to 99 years with a weighted average remaining lease term remaining of 52.1 years, excluding renewal options. The Company's discount rates, which approximates the Company's incremental borrowing rate, ranged from 3.8% for leases expiring in 2021 to 6.2% for leases expiring in 2115. The Company utilized a third party to assist in determining the discount rates for its ground leases. The discount rates consider the general economic environment and factor in various financing and asset specific adjustments so that the discount rate is appropriate for the intended use of the underlying lease. As of January 1, 2019, the Company recognized the present value of its lease payments and a corresponding lease liability of $91.7 million . In addition, the Company reclassified $45.0 million of prepaid ground leases and below-market lease intangibles from the Other assets line item, $1.9 million of above-market lease intangibles from the Other liabilities line and $8.4 million of straight-line rent from the Accounts payable and accrued liabilities line item to the Operating lease right-of-use assets line item on the Consolidated Balance Sheet. For lessors, the new standard requires a lessor to classify leases as either sales-type, direct-financing or operating. A lease will be treated as a sale if it is considered to transfer control of the underlying asset to the lessee. A lease will be classified as direct-financing if risks and rewards are conveyed without the transfer of control. Otherwise, the lease is treated as an operating lease. Lessor accounting remains largely unchanged with some exceptions including the concept of separating lease and nonlease components. Nonlease components, such as common area maintenance, are generally accounted for under Topic 606 and separated from the lease payments. However, the Company elected the lessor practical expedient allowing the Company to not separate these components when certain conditions are met. The combined component is accounted for under Topic 842. The adoption of Topic 842, where the Company is the lessor, did not have a material impact on the Company's Consolidated Financial Statements for the twelve months ended months ended December 31, 2019 . The new standard was effective for the Company on January 1, 2019. Topic 842 provides two transition alternatives. The Company elected the prospective optional transition method available to apply Topic 842 in the year of adoption and the guidance in Accounting Standards Codification Topic 840 in the comparative periods. Topic 842 includes extensive quantitative and qualitative disclosures as compared to Topic 840, Leases, for both lessees and lessors. See Note 3 to the Company's Consolidated Financial Statements for additional disclosures. Accounting Standards Update No. 2016-13 In June 2016, the FASB issued ASU 2016-13, "Measurement of Credit Losses on Financial Instruments." This update is intended to improve financial reporting by requiring timelier recognition of credit losses on loans and other financial instruments that are not accounted for at fair value through net income, including loans held for investment, held-to-maturity debt securities, trade and other receivables, net investment in leases and other such commitments. This update requires that financial statement assets measured at an amortized cost and certain other financial instruments be presented at the net amount expected to be collected, through an allowance for credit losses that is deducted from the amortized cost basis. This standard is effective for annual and interim periods beginning after December 15, 2019 with early adoption permitted. Operating lease receivables, representing the majority of the Company's receivables, are not within the scope of the new standard. The Company adopted this standard as of January 1, 2020. There was a not material impact to the Consolidated Financial Statements from the adoption of this standard. Accounting Standards Update No. 2017-04 In January 2017, the FASB issued ASU 2017-04, "Simplifying the Test for Goodwill Impairment." This update eliminates Step 2 of the goodwill impairment test. As such, an entity will perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize a goodwill impairment charge for the amount by which the reporting unit's carrying amount exceeds its fair value. This standard is effective for the Company for annual and interim periods beginning after December 15, 2019. The Company adopted this standard as of January 1, 2020. There was not a material impact to the Consolidated Financial Statements from the adoption of this standard.

Property Investments

Property Investments	12 Months Ended
	Dec. 31, 2019
Real Estate Investment Property, Net [Abstract]
Property Investments	Property Investments The Company invests in healthcare-related properties located throughout the United States. The Company provides management, leasing, development and redevelopment services, and capital for the construction of new facilities as well as for the acquisition of existing properties. The following table summarizes the Company’s investments at December 31, 2019. Dollars in thousands NUMBER OF PROPERTIES LAND BUILDINGS, IMPROVEMENTS, AND LEASE INTANGIBLES PERSONAL PROPERTY TOTAL ACCUMULATED DEPRECIATION Seattle, WA 25 $ 58,565 $ 532,767 $ 421 $ 591,753 $ (88,890 ) Dallas, TX 25 19,194 496,683 442 516,319 (181,556 ) Los Angeles, CA 14 44,386 205,829 347 250,562 (95,979 ) Atlanta, GA 9 3,679 212,509 84 216,272 (20,040 ) Nashville, TN 6 20,053 180,463 1,109 201,625 (64,038 ) Charlotte, NC 16 4,200 176,261 105 180,566 (67,040 ) Denver, CO 9 16,514 134,004 271 150,789 (25,265 ) Washington, D.C. 6 — 150,304 21 150,325 (25,097 ) Richmond, VA 7 — 149,132 106 149,238 (44,204 ) Houston, TX 9 16,211 132,013 78 148,302 (44,229 ) Honolulu, HI 3 8,327 135,641 159 144,127 (39,165 ) Des Moines, IA 7 12,665 126,401 99 139,165 (34,725 ) Oklahoma City, OK 4 10,401 115,706 15 126,122 (19,351 ) Indianapolis, IN 4 3,299 118,847 — 122,146 (26,082 ) San Francisco, CA 3 14,054 107,396 43 121,493 (20,906 ) Springfield, MO 1 1,989 109,304 — 111,293 (17,740 ) Austin, TX 5 14,236 92,809 123 107,168 (24,048 ) Memphis, TN 7 5,241 92,508 194 97,943 (37,582 ) San Antonio, TX 6 6,487 88,583 404 95,474 (40,573 ) Chicago, IL 3 5,859 87,588 211 93,658 (23,540 ) Minneapolis, MN 4 2,090 62,359 — 64,449 (10,486 ) Other (16 markets) 31 17,079 475,409 806 493,294 (165,159 ) 204 284,529 3,982,516 5,038 4,272,083 (1,115,695 ) Construction in progress — — 48,731 — 48,731 — Land held for development — 24,647 — — 24,647 (671 ) Memphis Redevelopment — 5,222 3,810 — 9,032 (50 ) Corporate property — — — 5,500 5,500 (4,686 ) Total real estate investments 204 $ 314,398 $ 4,035,057 $ 10,538 $ 4,359,993 $ (1,121,102 )

Leases

Leases	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Leases, Operating	Leases Lessor Accounting Under ASC 842 The Company’s properties generally are leased pursuant to non-cancelable, fixed-term operating leases with expiration dates through 2035. Some leases provide for fixed rent renewal terms in addition to market rent renewal terms. Some leases provide the lessee, during the term of the lease, with an option or right of first refusal to purchase the leased property. The Company’s portfolio of single-tenant net leases generally requires the lessee to pay minimum rent and all taxes (including property tax), insurance, maintenance and other operating costs associated with the leased property. The Company records these expenses on a net basis, with the exception of property taxes. Property taxes are recorded on a gross basis as a lessor cost in which the tenant reimburses the Company. The Company generally expects that collectibility is probable at lease commencement. If the assessment of collectibility changes after the lease commencement date and Rental income is not considered probable, Rental income is recognized on a cash basis and all previously recognized uncollectible Rental income is reversed in the period in which the it is determined not to be probable of collection. In addition to the lease-specific collectibility assessment performed under Topic 842, the Company may also apply a general reserve ("provision for bad debt"), as a reduction to Rental income, for its portfolio of operating lease receivables. The Company's leases typically have escalators that are either based on a stated percentage or an index such as CPI (consumer price index). In addition, most of the Company's leases include nonlease components such as reimbursement of operating expenses as additional rent or include the reimbursement of expected operating expenses as part of the lease payment. The Company adopted an accounting policy to combine lease and nonlease components. Rent escalators based on indices and reimbursements of operating expenses that are not included in the lease rate are considered variable lease payments. Variable payments are recognized in the period earned. Lease income for the Company's operating leases recognized for the twelve months ended December 31, 2019 was $462.2 million . Future minimum lease payments under the non-cancelable operating leases, excluding any reimbursements, as of December 31, 2019 are as follows: In thousands 2020 $ 360,340 2021 315,426 2022 275,798 2023 233,424 2024 177,738 2025 and thereafter 501,849 $ 1,864,575 Revenue Concentrations The Company’s real estate portfolio is leased to a diverse tenant base. The Company did not have any customers that account for 10% or more of the Company's revenues for the years ended December 31, 2019, 2018 and 2017. Purchase Option Provisions Certain of the Company’s leases include purchase option provisions. The provisions vary by agreement but generally allow the lessee to purchase the property covered by the agreement at fair market value or an amount equal to the Company’s gross investment . The Company expects that the purchase price from its purchase options will be greater than its net investment in the properties at the time of potential exercise by the lessee. The Company had investments of approximately $96.0 million in four real estate properties as of December 31, 2019 that were subject to purchase options that were exercisable. Lessor Accounting Under ASC 840 The Company’s properties are generally leased pursuant to non-cancelable, fixed-term operating leases with expiration dates through 2036. Some leases and financial arrangements provide for fixed rent renewal terms in addition to market rent renewal terms. Some leases provide the lessee, during the term of the lease and for a short period thereafter, with an option or a right of first refusal to purchase the leased property. The Company’s portfolio of single-tenant net leases generally requires the lessee to pay minimum rent and all taxes (including property tax), insurance, maintenance and other operating costs associated with the leased property. Future minimum lease payments under the non-cancelable operating leases, excluding any reimbursements, as of December 31, 2018 were as follows: In thousands 2019 $ 326,441 2020 279,211 2021 235,660 2022 201,072 2023 163,978 2024 and thereafter 476,673 $ 1,683,035 Lessee Accounting Under ASC 842 As of December 31, 2019 , the Company was obligated, as the lessee, under operating lease agreements consisting primarily of the Company’s ground leases. As of December 31, 2019 , the Company had 108 properties totaling 8.9 million square feet that were held under ground leases. Some of the ground leases renewal terms are based on fixed rent renewal terms and others have market rent renewal terms. These ground leases typically have initial terms of 40 to 99 years with expiration dates through 2117. Any rental increases related to the Company’s ground leases are generally either stated or based on the Consumer Price Index. The Company had 46 prepaid ground leases as of December 31, 2019 . The amortization of the prepaid rent, included in the operating lease right-of-use asset, represented approximately $0.6 million for the twelve months ended December 31, 2019 , 2018 and 2017 respectively. The Company’s future lease payments (primarily for its 62 non-prepaid ground leases) as of December 31, 2019 were as follows: In thousands OPERATING FINANCING 2020 $ 4,814 $ 746 2021 4,844 754 2022 4,875 763 2023 4,913 774 2024 4,969 795 2025 and thereafter 307,665 83,404 Total undiscounted lease payments 332,080 87,236 Discount (240,506 ) (69,199 ) Lease liabilities $ 91,574 $ 18,037 Lessee Accounting Under ASC 840 As of December 31, 2018, the Company was obligated under operating lease agreements consisting primarily of the Company’s ground leases. At December 31, 2018 the Company had 107 properties totaling 8.8 million square feet that were held under ground leases with a remaining weighted average term of 53.9 years, excluding renewal options. These ground leases typically have initial terms of 50 to 75 years with one or more renewal options extending the terms to 75 to 100 years, with expiration dates through 2117 . Any rental increases related to the Company’s ground leases are generally either stated or based on the Consumer Price Index. The Company’s future minimum lease payments (primarily for its 60 non-prepaid ground leases) as of December 31, 2018 were as follows: In thousands 2019 $ 5,288 2020 5,260 2021 5,238 2022 5,207 2023 5,224 2024 and thereafter 323,533 $ 349,750 The following table provides details of the Company's total lease expense for the year ended December 31, 2019 : In thousands YEAR ENDED Dec. 31, 2019 Operating lease cost Operating lease expense $ 4,623 Variable lease expense 3,161 Finance lease cost Amortization of right-of-use assets 165 Interest on lease liabilities 616 Total lease expense $ 8,565 Other information Operating cash flows outflows related to operating leases $ 6,972 Financing cash flows outflows related to financing leases $ 379 Right-of-use assets obtained in exchange for new finance lease liabilities $ 17,800 Weighted-average remaining lease term (excluding renewal options) - operating leases 49.5 Weighted-average remaining lease term (excluding renewal options) -finance leases 65.2 Weighted-average discount rate - operating leases 5.7 % Weighted-average discount rate - finance leases 5.4 %
Leases, Finance	Leases Lessor Accounting Under ASC 842 The Company’s properties generally are leased pursuant to non-cancelable, fixed-term operating leases with expiration dates through 2035. Some leases provide for fixed rent renewal terms in addition to market rent renewal terms. Some leases provide the lessee, during the term of the lease, with an option or right of first refusal to purchase the leased property. The Company’s portfolio of single-tenant net leases generally requires the lessee to pay minimum rent and all taxes (including property tax), insurance, maintenance and other operating costs associated with the leased property. The Company records these expenses on a net basis, with the exception of property taxes. Property taxes are recorded on a gross basis as a lessor cost in which the tenant reimburses the Company. The Company generally expects that collectibility is probable at lease commencement. If the assessment of collectibility changes after the lease commencement date and Rental income is not considered probable, Rental income is recognized on a cash basis and all previously recognized uncollectible Rental income is reversed in the period in which the it is determined not to be probable of collection. In addition to the lease-specific collectibility assessment performed under Topic 842, the Company may also apply a general reserve ("provision for bad debt"), as a reduction to Rental income, for its portfolio of operating lease receivables. The Company's leases typically have escalators that are either based on a stated percentage or an index such as CPI (consumer price index). In addition, most of the Company's leases include nonlease components such as reimbursement of operating expenses as additional rent or include the reimbursement of expected operating expenses as part of the lease payment. The Company adopted an accounting policy to combine lease and nonlease components. Rent escalators based on indices and reimbursements of operating expenses that are not included in the lease rate are considered variable lease payments. Variable payments are recognized in the period earned. Lease income for the Company's operating leases recognized for the twelve months ended December 31, 2019 was $462.2 million . Future minimum lease payments under the non-cancelable operating leases, excluding any reimbursements, as of December 31, 2019 are as follows: In thousands 2020 $ 360,340 2021 315,426 2022 275,798 2023 233,424 2024 177,738 2025 and thereafter 501,849 $ 1,864,575 Revenue Concentrations The Company’s real estate portfolio is leased to a diverse tenant base. The Company did not have any customers that account for 10% or more of the Company's revenues for the years ended December 31, 2019, 2018 and 2017. Purchase Option Provisions Certain of the Company’s leases include purchase option provisions. The provisions vary by agreement but generally allow the lessee to purchase the property covered by the agreement at fair market value or an amount equal to the Company’s gross investment . The Company expects that the purchase price from its purchase options will be greater than its net investment in the properties at the time of potential exercise by the lessee. The Company had investments of approximately $96.0 million in four real estate properties as of December 31, 2019 that were subject to purchase options that were exercisable. Lessor Accounting Under ASC 840 The Company’s properties are generally leased pursuant to non-cancelable, fixed-term operating leases with expiration dates through 2036. Some leases and financial arrangements provide for fixed rent renewal terms in addition to market rent renewal terms. Some leases provide the lessee, during the term of the lease and for a short period thereafter, with an option or a right of first refusal to purchase the leased property. The Company’s portfolio of single-tenant net leases generally requires the lessee to pay minimum rent and all taxes (including property tax), insurance, maintenance and other operating costs associated with the leased property. Future minimum lease payments under the non-cancelable operating leases, excluding any reimbursements, as of December 31, 2018 were as follows: In thousands 2019 $ 326,441 2020 279,211 2021 235,660 2022 201,072 2023 163,978 2024 and thereafter 476,673 $ 1,683,035 Lessee Accounting Under ASC 842 As of December 31, 2019 , the Company was obligated, as the lessee, under operating lease agreements consisting primarily of the Company’s ground leases. As of December 31, 2019 , the Company had 108 properties totaling 8.9 million square feet that were held under ground leases. Some of the ground leases renewal terms are based on fixed rent renewal terms and others have market rent renewal terms. These ground leases typically have initial terms of 40 to 99 years with expiration dates through 2117. Any rental increases related to the Company’s ground leases are generally either stated or based on the Consumer Price Index. The Company had 46 prepaid ground leases as of December 31, 2019 . The amortization of the prepaid rent, included in the operating lease right-of-use asset, represented approximately $0.6 million for the twelve months ended December 31, 2019 , 2018 and 2017 respectively. The Company’s future lease payments (primarily for its 62 non-prepaid ground leases) as of December 31, 2019 were as follows: In thousands OPERATING FINANCING 2020 $ 4,814 $ 746 2021 4,844 754 2022 4,875 763 2023 4,913 774 2024 4,969 795 2025 and thereafter 307,665 83,404 Total undiscounted lease payments 332,080 87,236 Discount (240,506 ) (69,199 ) Lease liabilities $ 91,574 $ 18,037 Lessee Accounting Under ASC 840 As of December 31, 2018, the Company was obligated under operating lease agreements consisting primarily of the Company’s ground leases. At December 31, 2018 the Company had 107 properties totaling 8.8 million square feet that were held under ground leases with a remaining weighted average term of 53.9 years, excluding renewal options. These ground leases typically have initial terms of 50 to 75 years with one or more renewal options extending the terms to 75 to 100 years, with expiration dates through 2117 . Any rental increases related to the Company’s ground leases are generally either stated or based on the Consumer Price Index. The Company’s future minimum lease payments (primarily for its 60 non-prepaid ground leases) as of December 31, 2018 were as follows: In thousands 2019 $ 5,288 2020 5,260 2021 5,238 2022 5,207 2023 5,224 2024 and thereafter 323,533 $ 349,750 The following table provides details of the Company's total lease expense for the year ended December 31, 2019 : In thousands YEAR ENDED Dec. 31, 2019 Operating lease cost Operating lease expense $ 4,623 Variable lease expense 3,161 Finance lease cost Amortization of right-of-use assets 165 Interest on lease liabilities 616 Total lease expense $ 8,565 Other information Operating cash flows outflows related to operating leases $ 6,972 Financing cash flows outflows related to financing leases $ 379 Right-of-use assets obtained in exchange for new finance lease liabilities $ 17,800 Weighted-average remaining lease term (excluding renewal options) - operating leases 49.5 Weighted-average remaining lease term (excluding renewal options) -finance leases 65.2 Weighted-average discount rate - operating leases 5.7 % Weighted-average discount rate - finance leases 5.4 %

Acquisitions, Dispositions and

Acquisitions, Dispositions and Mortgage Repayments	12 Months Ended
	Dec. 31, 2019
Acquisitions and Dispositions and Mortgage Repayments [Abstract]
Acquisitions, Dispositions and Mortgage Repayments	Acquisitions, Dispositions and Mortgage Repayments 2019 Acquisitions The following table details the Company's acquisitions for the year ended December 31, 2019 : Dollars in millions TYPE 1 DATE ACQUIRED PURCHASE PRICE CASH 2 REAL ESTATE OTHER 3 SQUARE FOOTAGE Washington, D.C. 4 MOB 3/28/19 $ 46.0 $ 45.9 $ 50.2 $ (4.3 ) 158,338 Indianapolis, IN 5 MOB 3/28/19 47.0 44.8 43.7 1.1 143,499 Atlanta, GA MOB 4/2/19 28.0 28.0 28.0 — 47,963 Dallas, TX MOB 6/10/19 17.0 16.7 17.0 (0.3 ) 89,990 Seattle, WA MOB 6/11/19 7.7 7.8 7.8 — 29,870 Seattle, WA MOB 6/14/19 19.0 19.1 19.5 (0.4 ) 47,255 Seattle, WA MOB 6/28/19 30.5 30.4 30.6 (0.2 ) 78,288 Houston, TX MOB 8/1/19 13.5 13.5 13.5 — 29,903 Oklahoma City, OK MOB 9/26/19 4.1 4.1 4.1 — 28,542 Los Angeles, CA 6 MOB 9/30/19 61.1 60.9 61.8 (0.9 ) 115,634 Raleigh, NC MOB 10/31/19 21.6 22.0 21.7 0.3 57,730 Dallas, TX 7 MOB 10/31/19 20.1 19.5 20.2 (0.7 ) 48,192 Seattle, WA MOB 11/18/19 22.8 23.1 23.2 (0.1 ) 36,350 Seattle, WA MOB 12/10/19 24.2 24.5 24.6 (0.1 ) 44,166 Memphis, TN MOB 12/13/19 8.7 8.9 8.9 — 110,883 Seattle, WA MOB 12/18/19 10.0 9.3 9.9 (0.6 ) 20,109 $ 381.3 $ 378.5 $ 384.7 $ (6.2 ) 1,086,712 1 MOB = medical office building. 2 Cash consideration excludes prorations of revenue and expense due to/from seller at the time of the acquisition. 3 Includes other assets acquired, liabilities assumed, and intangibles recognized at acquisition. 4 Includes two properties. The Company assumed two ground leases in connection with this acquisition that are classified as financing leases. The present value of future lease payments totaling $14.3 million was recorded on the Company's Consolidated Balance Sheets under the caption Finance lease liabilities. In addition, the right-of-use assets were partially offset by $5.2 million of above-market lease intangibles included in Other. 5 The Company assumed a prepaid ground lease totaling $0.8 million and recorded a below-market lease intangible totaling $0.9 million in connection with this acquisition that is classified as an operating lease that is included in Other. 6 Includes two properties. 7 The Company assumed a ground lease in connection with this acquisition that is classified as a financing lease. The present value of future lease payments totaling $3.6 million was recorded on the Company's Consolidated Balance Sheets under the caption Finance lease liabilities. The following table summarizes the estimated relative fair values of the assets acquired and liabilities assumed in the real estate acquisitions for 2019 as of the acquisition date: ESTIMATED FAIR VALUE in millions ESTIMATED USEFUL LIFE in years Building $ 270.7 8.0 - 37.0 Land 59.1 — Land Improvements 4.2 3.0 - 12.0 Intangibles At-market lease intangibles 50.7 3.3 - 9.2 Above-market lease intangibles (lessor) 0.7 2.4 - 9.9 Below-market lease intangibles (lessor) (0.7 ) 1.2 - 8.6 Above-market lease intangibles (lessee) (5.1 ) 69.1 - 72.3 Below-market lease intangibles (lessee) 0.9 65.1 Other assets acquired 2.3 Accounts payable, accrued liabilities and other liabilities assumed (4.3 ) Total cash paid $ 378.5 Subsequent Acquisition On January 3, 2020, the Company acquired an 86,986 square foot medical office building in Los Angeles, California for a purchase price of $42.0 million . 2018 Real Estate Acquisitions The following table details the Company's acquisitions for the year ended December 31, 2018: Dollars in millions TYPE 1 DATE ACQUIRED PURCHASE PRICE MORTGAGE NOTES PAYABLE ASSUMED 2 CASH 3 REAL ESTATE OTHER 4 SQUARE FOOTAGE Seattle, WA MOB 5/4/18 $ 7.8 $ — $ 7.8 $ 7.8 $ — 13,314 Denver, CO 5 MOB 5/18/18 12.1 (8.0 ) 3.8 12.1 (0.2 ) 93,992 Denver, CO 5 OFC 5/18/18 12.9 — 12.8 13.0 (0.2 ) 93,869 Oklahoma City, OK MOB 5/21/18 11.4 — 11.4 11.5 (0.1 ) 82,647 Seattle, WA MOB 6/29/18 26.2 — 26.2 26.7 (0.5 ) 86,942 Denver, CO MOB 8/24/18 4.1 — 4.2 4.2 — 17,084 Nashville, TN OFC 12/4/18 31.9 — 32.0 32.0 — 108,691 Chicago, IL 6 MOB 12/19/18 5.1 — 4.9 5.1 (0.2 ) 14,883 $ 111.5 $ (8.0 ) $ 103.1 $ 112.4 $ (1.2 ) 511,422 1 MOB = medical office building; OFC = office 2 The mortgage note payable assumed in the acquisition does not reflect the fair value premium totaling $0.1 million recorded by the Company upon acquisition (included in Other). 3 Cash consideration excludes prorations of revenue and expense due to/from seller at the time of the acquisition. 4 Includes other assets acquired, liabilities assumed, intangibles recognized at acquisition and fair value adjustments on debt assumed. 5 The mortgage note payable assumed at acquisition encumbers both buildings. 6 The Company acquired an additional suite in a previously acquired medical office building. The following table summarizes the estimated relative fair values of the assets acquired and liabilities assumed in the real estate acquisitions for 2018 as of the acquisition date: ESTIMATED FAIR VALUE in millions ESTIMATED USEFUL LIFE in years Building $ 64.0 20.0 - 30.0 Land 31.4 — Land Improvements 2.7 5.0 - 13.5 Intangibles At-market lease intangibles (lessor) 14.3 1.3 - 4.2 Below-market lease intangibles (lessor) (0.1 ) 3.8 Mortgage notes payable assumed, including fair value adjustments (8.0 ) Other assets acquired 0.2 Accounts payable, accrued liabilities and other liabilities assumed (1.4 ) Total cash paid $ 103.1 Non-monetary Exchange On June 29, 2018, the Company completed the swap of a non-revenue producing garage that was built by the Company in 2012 located in Denver, Colorado for 20.5 acres of land adjacent to the CommonSpirit Health's St. Anthony Hospital campus. A portion of this land, approximately 4.6 acres, has been allocated to an existing medical office building that was developed by the Company in 2017. This building is located on land previously ground leased from the hospital. The remaining land has been recorded in land held for development. The land acquired was appraised for $5.8 million . The Company had a net investment of $3.9 million in the parking garage and recognized a gain of $1.9 million in connection with this transaction. 2019 Real Estate Asset Dispositions The following table details the Company's dispositions for the year ended December 31, 2019 : Dollars in millions TYPE 1 DATE DISPOSED SALES PRICE CLOSING ADJUSTMENTS NET PROCEEDS NET REAL ESTATE INVESTMENT OTHER 2 GAIN/ SQUARE FOOTAGE Tucson, AZ 3 MOB 4/9/19 $ 13.0 $ (0.9 ) $ 12.1 $ 6.9 $ 0.4 $ 4.8 67,345 Virginia Beach, VA 4 MOB 8/1/19 1.3 (0.1 ) 1.2 1.2 — — 10,000 San Antonio, TX MOB 8/28/19 0.9 (0.1 ) 0.8 0.6 — 0.2 10,138 Erie, PA IRF 10/25/19 14.0 — 14.0 1.3 — 12.7 90,123 New Orleans, LA 5 MOB 11/25/19 3.7 (0.2 ) 3.5 1.2 0.2 2.1 136,155 Kingsport, TN SNF 11/27/19 9.5 (0.3 ) 9.2 5.0 1.3 2.9 75,000 Pittsburgh, PA 6 IRF 12/18/19 3.8 (0.3 ) 3.5 3.5 — — 78,731 Dallas, TX 5 MOB 12/30/19 8.7 (0.6 ) 8.1 6.1 (0.4 ) 2.4 69,558 $ 54.9 $ (2.5 ) $ 52.4 $ 25.8 $ 1.5 $ 25.1 537,050 1 MOB = medical office building; IRF = inpatient rehabilitation facility; SNF = skilled nursing facility 2 Includes straight-line rent receivables, leasing commissions and lease inducements. 3 Includes four properties sold to a single purchaser. 4 The Company reclassified this property to held for sale during the second quarter of 2019 and recorded an impairment charge of $0.4 million based on the sales price less estimated costs to sell. 5 Includes two properties. 6 The Company reclassified this property to held for sale during the first quarter of 2017 and subsequently in the second quarter of 2019, the Company accepted an offer to purchase and recorded an impairment charge of $5.2 million . 2018 Real Estate Asset Dispositions The following table details the Company's dispositions for the year ended December 31, 2018: Dollars in millions TYPE 1 DATE DISPOSED SALES PRICE CLOSING ADJUSTMENTS NET PROCEEDS NET REAL ESTATE INVESTMENT OTHER 3 GAIN/ SQUARE FOOTAGE Roanoke, VA 2, 4 MOB, OFC 4/26/18 $ 46.2 $ — $ 46.2 $ 23.9 $ — $ 22.3 460,881 Michigan 5 SNF 6/27/18 9.5 (0.7 ) 8.8 3.4 — 5.4 121,672 St. Louis, MO MOB 8/30/18 9.8 (0.5 ) 9.3 7.5 0.5 1.3 70,893 Denver, CO IRF 12/20/18 16.9 (0.3 ) 16.6 9.2 1.4 6.0 34,068 Cleveland, TN MOB 12/21/18 13.3 (0.2 ) 13.1 8.6 0.4 4.1 81,382 Tucson, AZ MOB 12/27/18 3.0 (0.2 ) 2.8 1.9 0.2 0.7 37,310 $ 98.7 $ (1.9 ) $ 96.8 $ 54.5 $ 2.5 $ 39.8 806,206 1 MOB = medical office building; IRF = inpatient rehabilitation facility; OFC = office; SNF = skilled nursing facility 2 Previously classified as held for sale. 3 Includes straight-line rent receivables, leasing commissions and lease inducements. 4 Includes seven properties and comprised of five single-tenant net lease buildings and two multi-tenant buildings. These buildings were sold pursuant to the exercise of a fixed-price purchase option. 5 Includes five skilled nursing facilities. Sales price includes $0.5 million of forfeited earnest money from a prior terminated transaction.

Held for Sale

Held for Sale	12 Months Ended
	Dec. 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Held for Sale	Held for Sale Assets and liabilities of properties sold or classified as held for sale are separately identified on the Company’s Consolidated Balance Sheets. As of December 31, 2019 the Company had no properties classified as held for sale, and as of December 31, 2018, the Company had one property classified as held for sale. The table below reflects the assets and liabilities of the properties classified as held for sale as of December 31, 2019 and 2018 . DECEMBER 31, Dollars in thousands 2019 2018 Balance Sheet data Land $ — $ 1,125 Buildings, improvements and lease intangibles — 18,231 — 19,356 Accumulated depreciation — (10,657 ) Real estate assets held for sale, net — 8,699 Other assets, net 37 573 Assets held for sale, net $ 37 $ 9,272 Accounts payable and accrued liabilities $ 37 $ 450 Other liabilities 108 137 Liabilities of properties held for sale $ 145 $ 587

Impairment Charges

Impairment Charges	12 Months Ended
	Dec. 31, 2019
Property, Plant and Equipment [Abstract]
Impairment Charges	Impairment Charges An asset is impaired when undiscounted cash flows expected to be generated by the asset are less than the carrying value of the asset. The Company must assess the potential for impairment of its long-lived assets, including real estate properties, whenever events occur or there is a change in circumstances, such as the sale of a property or the decision to sell a property, that indicate that the recorded value might not be fully recoverable. The Company recorded impairment charges on properties sold or classified as held for sale for the years ended December 31, 2019 and 2017 totaling $5.6 million and $5.4 million , respectively. The Company did no

Other Assets

Other Assets	12 Months Ended
	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Assets	Other Assets Other assets consist primarily of straight-line rent receivables, additional long-lived assets, prepaids, intangible assets, debt issuance costs and accounts receivable. Items included in "Other assets, net" on the Company’s Consolidated Balance Sheets as of December 31, 2019 and 2018 are detailed in the table below: DECEMBER 31, Dollars in millions 2019 2018 Straight-line rent receivables $ 70.5 $ 69.5 Prepaid assets 44.3 66.2 Additional long-lived assets, net 22.7 23.5 Accounts receivable, net 13.0 9.7 Ground lease modification, net 9.4 9.9 Equity investments in joint ventures 8.1 8.5 Debt issuance costs, net 1 5.0 2.2 Project costs 4.6 2.2 Goodwill 3.5 3.5 Customer relationship intangible assets, net 2.5 1.7 Above-market intangible assets, net 2 1.2 16.8 Interest rate swap assets — 0.2 Other 0.6 0.8 $ 185.4 $ 214.7 1 Includes debt issuance costs related to the Company's Unsecured Credit Facility and Unsecured Term Loan due 2026. 2 Includes below-market ground lease intangibles as of December 31, 2018. These intangibles were reclassified to Operating right-of-use assets on the Company's Consolidated Balance Sheets as of December 31, 2019. Unconsolidated Joint Ventures The Company owns a non-managing membership interest in two limited liability companies, or LLCs, that own two parking garages in Atlanta, Georgia which is included in the equity investments in the joint ventures line in the table above. The parking garage interests were purchased in connection with three buildings that were acquired in the fourth quarter of 2017. The Company's investment in and income (loss) recognized for the years ended December 31, 2019 and 2018 related to its LLCs accounted for under the equity method are shown in the table below: DECEMBER 31, Dollars in millions 2019 2018 Net LLC investments, beginning of period $ 8.5 $ 8.7 Equity income (loss) recognized during the period — — Owner distributions (0.4 ) (0.2 ) Net LLC investments, end of period $ 8.1 $ 8.5

Intangible Assets and Liabiliti

Intangible Assets and Liabilities	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible Assets and Liabilities	Intangible Assets and Liabilities The Company has several types of intangible assets and liabilities included in its Consolidated Balance Sheets, including goodwill, debt issuance costs, above-, below-, and at-market lease intangibles, and customer relationship intangibles. The Company’s intangible assets and liabilities as of December 31, 2019 and 2018 consisted of the following: GROSS BALANCE at December 31, ACCUMULATED AMORTIZATION at December 31, WEIGHTED AVG. REMAINING LIFE in years BALANCE SHEET CLASSIFICATION Dollars in millions 2019 2018 2019 2018 Goodwill $ 3.5 $ 3.5 $ — $ — N/A Other assets, net Credit facility debt issuance costs 5.8 5.4 0.8 3.2 3.8 Other assets, net Above-market lease intangibles (lessor) 4.0 4.5 2.8 3.3 3.9 Other assets, net Customer relationship intangibles (lessor) 4.1 2.7 1.6 1.0 43.1 Other assets, net Below-market lease intangibles (7.3 ) (7.3 ) (4.0 ) (4.0 ) 6.7 Other liabilities Debt issuance costs 1 9.2 9.3 3.5 2.8 5.8 Notes and bonds payable At-market lease intangibles 147.9 114.4 59.8 52.0 5.4 Real estate properties Above-market lease intangibles (lessee) (7.2 ) (2.0 ) (0.2 ) (0.1 ) 75.5 Right-of-use asset Below-market lease intangibles (lessee) 18.8 17.8 2.5 2.2 63.0 Right-of-use asset $ 178.8 $ 148.3 $ 66.8 $ 60.4 16.6 1 Includes debt issuance costs related to the Company's Unsecured Senior Notes payable, Unsecured Term Loan due 2024, and mortgage notes payable. For the years ended December 31, 2019 and 2018, the Company recognized approximately $28.0 million and $23.2 million of intangible amortization expense, respectively. The following table represents expected amortization over the next five years of the Company’s intangible assets and liabilities in place as of December 31, 2019 : Dollars in millions FUTURE AMORTIZATION OF INTANGIBLES, NET 2019 $ 24.1 2020 19.1 2021 16.0 2022 11.2 2023 7.0

Notes and Bonds Payable

Notes and Bonds Payable	12 Months Ended
	Dec. 31, 2019
Debt Disclosure [Abstract]
Notes and Bonds Payable	Notes and Bonds Payable DECEMBER 31, MATURITY DATES CONTRACTUAL INTEREST RATES PRINCIPAL PAYMENTS INTEREST PAYMENTS Dollars in thousands 2019 2018 Unsecured Credit Facility $ 293,000 $ 262,000 5/23 LIBOR + .90% At maturity Monthly Unsecured Term Loan due 2024 1 199,013 149,183 5/24 LIBOR + 1.00% At maturity Monthly Unsecured Term Loan due 2026 2 — — 6/26 LIBOR + 1.60% At maturity Monthly Senior Notes due 2023 1 248,540 248,117 4/23 3.75 % At maturity Semi-Annual Senior Notes due 2025 1 248,522 248,278 5/25 3.88 % At maturity Semi-Annual Senior Notes due 2028 1 295,651 295,198 1/28 3.63 % At maturity Semi-Annual Mortgage notes payable 3 129,343 143,208 7/20-5/40 3.31%-6.88% Monthly Monthly $ 1,414,069 $ 1,345,984 1 Balances are shown net of discounts and unamortized issuance costs. 2 As of December 31, 2019, there are no outstanding loans under the Unsecured Term Loan 2026. This term loan has a delayed draw feature that allows the Company up to February 2020 to draw against the $150 million commitments. 3 Balances are shown net of discounts and unamortized issuance costs and include premiums. The Company’s various debt agreements contain certain representations, warranties, and financial and other covenants customary in such loan agreements. Among other things, these provisions require the Company to maintain certain financial ratios and impose certain limits on the Company’s ability to incur indebtedness and create liens or encumbrances. As of December 31, 2019 , the Company was in compliance with its financial covenant provisions under its various debt instruments. Unsecured Credit Facility On October 14, 2011, the Company entered into a $700.0 million unsecured credit facility with a syndicate of lenders. On May 31, 2019, the Company entered into an amended and restated Unsecured Credit Facility to extend the maturity date to May 2023. The credit facility agreement provides the Company with two six -month extension options that could extend the maturity date to May 2024. Each option is subject to an extension fee of 0.0625% of the aggregate commitments. Amounts outstanding under the Unsecured Credit Facility bear interest at LIBOR plus an applicable margin rate. The margin rate, which depends on the Company's credit ratings, ranges from 0.775% to 1.45% ( 0.90% as of December 31, 2019 ). In addition, the Company pays a facility fee per annum on the aggregate amount of commitments ranging from 0.125% to 0.30% ( 0.20% as of December 31, 2019 ). In connection with the amendment, the Company paid up-front fees to the lenders of approximately $3.5 million , which will be amortized over the term of the facility. As of December 31, 2019 , the Company had $293.0 million outstanding under the Unsecured Credit Facility with an effective interest rate of approximately 2.66% and had a remaining borrowing capacity of approximately $407.0 million. Unsecured Term Loan due 2024 In February 2014, the Company entered into a $200.0 million unsecured term loan with a syndicate of nine lenders. On July 5, 2016, the Company repaid $50.0 million of the outstanding principal. On May 31, 2019, the Company entered into an amendment to the unsecured term loan due 2022 with a syndicate of nine lenders to extend the maturity date to May 2024 and to increase the loan amount from $150.0 million to $200 million . The Unsecured Term Loan due 2024 bears interest at a rate equal to (x) LIBOR plus (y) a margin ranging from 0.85% to 1.65% ( 1.00% as of December 31, 2019 ) based upon the Company's unsecured debt ratings. Payments under the Unsecured Term Loan due 2024 are interest only, with the full amount of the principal due at maturity. The Unsecured Term Loan due 2024 may be prepaid at any time, without penalty. The Unsecured Term Loan due 2024 has various financial covenant provisions that are required to be met on a quarterly and annual basis that are equivalent to those of the Unsecured Credit Facility. As of December 31, 2019 , the Company had interest rate swaps totaling $175.0 million to hedge the 1-month LIBOR portion of the cost of borrowing under the Unsecured Term Loan due 2024 at a weighted average rate of 2.29% . The outstanding balance on the Unsecured Term Loan due 2024 was $200.0 million as of December 31, 2019 with an effective interest rate of approximately 3.27% including the impact of the interest rate swaps. In connection with the amendment, the Company paid up-front fees to the lenders of approximately $0.7 million , of which $0.4 million was capitalized and will be amortized over the term of the loan, and $0.3 million was expensed during the second quarter of 2019. For each of the years ended December 31, 2019 , 2018 , and 2017 the Company amortized approximately $0.2 million of the debt issuance costs which is included in interest expense on the Company's Consolidated Statements of Income. The following table reconciles the balance of the Unsecured Term Loan due 2024 on the Company’s Consolidated Balance Sheets as of December 31, 2019 and 2018 : DECEMBER 31, Dollars in thousands 2019 2018 Unsecured Term Loan due 2024 principal balance $ 200,000 $ 150,000 Debt issuance costs (987 ) (817 ) Unsecured Term Loan due 2024 carrying amount $ 199,013 $ 149,183 Unsecured Term Loan due 2026 On May 31, 2019, the Company amended and restated its term loan agreement with a syndicate of lenders. The Unsecured Term Loan due 2026 has a delayed draw feature that allows the Company up to nine months to draw against the $150.0 million commitments. Loans outstanding under the Unsecured Term Loan due 2026 will bear interest at a rate equal to LIBOR plus a margin ranging from 1.45% to 2.40% ( 1.60% at December 31, 2019 ). As of December 31, 2019 , no loans were outstanding under the Unsecured Term Loan due 2026. Committed amounts that remain undrawn are subject to a ticking fee ranging from 0.125% to 0.30% per annum ( 0.20% at December 31, 2019 ). In connection with the amendment, the Company paid up-front fees to the lenders of approximately $1.1 million , of which $0.7 million was capitalized and will be amortized over the term of the loan, and $0.4 million was expensed during the second quarter of 2019. Senior Notes due 2023 On March 26, 2013, the Company issued $250.0 million of unsecured senior notes due 2023 (the "Senior Notes due 2023") in a registered public offering. The Senior Notes due 2023 bear interest at 3.75% , payable semi-annually on April 15 and October 15, beginning October 15, 2013, and are due on April 15, 2023, unless redeemed earlier by the Company. The notes were issued at a discount of approximately $2.1 million and the Company incurred debt issuance cost of $2.1 million , which yielded a 3.95% interest rate per annum upon issuance. For each of the years ended December 31, 2019 , 2018 and 2017 , the Company amortized approximately $0.2 million of the discount and $0.2 million of the debt issuance cost which are included in interest expense on the Company’s Consolidated Statements of Income. The following table reconciles the balance of the Senior Notes due 2023 on the Company’s Consolidated Balance Sheets as of December 31, 2019 and 2018 : DECEMBER 31, Dollars in thousands 2019 2018 Senior Notes due 2023 face value $ 250,000 $ 250,000 Unaccreted discount (761 ) (974 ) Debt issuance costs (699 ) (909 ) Senior Notes due 2023 carrying amount $ 248,540 $ 248,117 Senior Notes due 2025 On April 24, 2015, the Company issued $250.0 million of unsecured senior notes due 2025 (the "Senior Notes due 2025") in a registered public offering. The Senior Notes due 2025 bear interest at 3.875% , payable semi-annually on May 1 and November 1, beginning November 1, 2015, and are due on May 1, 2025, unless redeemed earlier by the Company. The notes were issued at a discount of approximately $0.2 million and the Company incurred approximately $2.3 million in debt issuance costs which yielded a 4.08% interest rate per annum upon issuance. For each of the years ended December 31, 2019 , 2018 , and 2017 the Company amortized approximately $0.2 million of the debt issuance costs which is included in interest expense on the Company's Consolidated Statements of Income. Concurrent with this transaction, the Company settled four forward starting swap agreements for $1.7 million . The Senior Notes due 2025 have various financial covenants that are required to be met on a quarterly and annual basis. The following table reconciles the balance of the Senior Notes due 2025 on the Company’s Consolidated Balance Sheets as of December 31, 2019 and 2018 : DECEMBER 31, Dollars in thousands 2019 2018 Senior Notes due 2025 face value $ 250,000 $ 250,000 Unaccreted discount (121 ) (141 ) Debt issuance costs (1,357 ) (1,581 ) Senior Notes due 2028 carrying amount $ 248,522 $ 248,278 Senior Notes due 2028 On December 11, 2017, the Company issued $300.0 million of unsecured Senior Notes due 2028 (the "Senior Notes due 2028") in a registered public offering. The Senior Notes due 2028 bear interest at 3.625% , payable semi-annually on January 15 and July 15, beginning July 15, 2018, and are due on January 15, 2028, unless redeemed earlier by the Company. The notes were issued at a discount of approximately $2.5 million and the Company incurred approximately $2.7 million in debt issuance costs which yielded a 3.84% interest rate per annum upon issuance. For the year ended December 31, 2019 , the Company amortized approximately $0.2 million of the discount and $0.2 million of the debt issuance costs which are included in interest expense on the Company's Consolidated Statements of Income. The Senior Notes due 2028 have various financial covenants that are required to be met on a quarterly and annual basis. The following table reconciles the balance of the Senior Notes due 2028 on the Company’s Consolidated Balance Sheets as of December 31, 2019 : DECEMBER 31, Dollars in thousands 2019 2018 Senior Notes due 2028 face value $ 300,000 $ 300,000 Unaccreted discount (2,100 ) (2,319 ) Debt issuance costs (2,249 ) (2,483 ) Senior Notes due 2028 carrying amount $ 295,651 $ 295,198 Mortgage Notes Payable The following table reconciles the Company’s aggregate mortgage notes principal balance with the Company’s Consolidated Balance Sheets as of December 31, 2019 and 2018 . For the years ended December 31, 2019 , 2018 and 2017 , the Company amortized approximately $0.6 million, $0.4 million and $0.3 million of the discount and $0.4 million, $0.8 million, and $0.7 million of the premium. For the years ended December 31, 2019 , 2018 and 2017 , the Company also amortized approximately $0.2 million, $0.1 million , and $0.1 million of the debt issuance costs, respectively, on the mortgage notes payable which is included in interest expense on the Company’s Consolidated Statements of Income. DECEMBER 31, Dollars in thousands 2019 2018 Mortgage notes payable principal balance $ 129,258 $ 143,115 Unamortized premium 1,162 1,805 Unaccreted discount (528 ) (968 ) Debt issuance costs (549 ) (744 ) Mortgage notes payable carrying amount $ 129,343 $ 143,208 The following table details the Company’s mortgage notes payable, with related collateral. ORIGINAL BALANCE EFFECTIVE INTEREST RATE 20 MATURITY DATE COLLATERAL 21 PRINCIPAL AND INTEREST PAYMENTS 19 INVESTMENT IN COLLATERAL at December 31, BALANCE at December 31, Dollars in millions 2019 2019 2018 Commercial Bank 1 $ 9.4 4.55 % 7/19 MOB Monthly/8-yr amort $ — $ — $ 9.0 Commercial Bank 2 15.2 7.65 % 7/20 MOB 18 18.6 12.5 12.5 Life Insurance Co. 3 7.9 4.00 % 8/20 MOB Monthly/15-yr amort. 20.7 0.5 1.3 Life Insurance Co. 4 7.3 5.25 % 8/20 MOB Monthly/27-yr amort. 18.1 6.0 6.2 Life Insurance Co. 5 5.6 4.30 % 1/21 MOB Monthly/10-yr amort. 15.8 4.5 4.6 Commercial Bank 6 12.9 6.43 % 2/21 MOB Monthly/12-yr amort. 55.2 10.1 10.3 Life Insurance Co. 7 11.0 3.87 % 11/22 MOB Monthly/7-yr amort. 22.0 10.0 10.2 Life Insurance Co. 8 12.3 3.86 % 8/23 MOB Monthly/7-yr amort. 25.4 10.9 11.2 Financial Services 9 12.4 4.27 % 10/23 MOB Monthly/10-yr amort. 22.6 11.7 12.0 Life Insurance Co. 10 9.0 4.84 % 12/23 MOB,OFC Monthly/10-yr amort. 25.7 7.6 7.8 Life Insurance Co. 11 13.3 4.13 % 1/24 MOB Monthly/10-yr amort. 20.8 12.7 13.0 Life Insurance Co. 12 6.8 3.96 % 2/24 MOB Monthly/7-yr amort. 14.6 6.4 6.6 Financial Services 13 9.7 4.32 % 9/24 MOB Monthly/10-yr amort. 17.0 8.3 8.6 Commercial Bank 11.5 3.71 % 1/26 MOB Monthly/10-yr amort. 38.6 9.6 10.1 Commercial Bank 14 15.0 5.25 % 4/27 MOB Monthly/20-yr amort. 33.5 7.9 8.8 Municipal Government 15, 16 11.0 4.79 % 17 MOB Semi-Annual 17 21.0 10.6 11.0 $ 369.6 $ 129.3 $ 143.2 1 The Company repaid this mortgage note in April 2019. The Company's unencumbered gross investment was $27.8 million at December 31, 2019. 2 The unaccreted portion of the $2.4 million discount recorded on this note upon acquisition is included in the balance above. 3 The unamortized portion of the $0.3 million premium recorded on this note upon acquisition is included in the balance above. 4 The unamortized portion of the $0.4 million premium recorded on this note upon acquisition is included in the balance above. This mortgage note payable was repaid in full on February 3, 2020. 5 The unamortized portion of the $0.2 million premium recorded on this note upon acquisition is included in the balance above. 6 The unaccreted portion of the $1.0 million discount recorded on this note upon acquisition is included in the balance above. 7 The unaccreted portion of the $0.1 million discount recorded on this note upon acquisition is included in the balance above. 8 The unaccreted portion of the $0.2 million discount recorded on this note upon acquisition is included in the balance above. 9 The unamortized portion of the $0.4 million premium recorded on this note upon acquisition is included in the balance above. 10 The unamortized portion of the $0.1 million premium recorded on this note upon acquisition is included in the balance above. 11 The unamortized portion of the $0.8 million premium recorded on this note upon acquisition is included in the balance above. 12 The unamortized portion of the $0.2 million premium recorded on this note upon acquisition is included in the balance above. 13 The unamortized portion of the $0.1 million premium recorded on this note upon acquisition is included in the balance above. 14 The unamortized portion of the $0.7 million premium recorded on this note upon acquisition is included in the balance above. 15 Balance consists of three notes secured by the same building. 16 The unamortized portion of the $1.0 million premium recorded on the three notes upon acquisition is included in the balance above. 17 These three mortgage notes payable are series municipal bonds that have maturity dates ranging from from May 2022 to May 2040. One of the four original notes payable was repaid upon maturity in May 2017. The remaining three require interest only payments and have future maturity dates but allow repayment after May 2020 without penalty. The Company intends on repaying all three notes payable at that time. 18 Payable in monthly installments of interest only for 24 months and then installments of principal and interest based on an 11 -year amortization with the final payment due at maturity. 19 Payable in monthly installments of principal and interest with the final payment due at maturity (unless otherwise noted). 20 The contractual interest rates for the 17 outstanding mortgage notes ranged from 3.3% to 6.9% as of December 31, 2019 . 21 MOB-Medical office building. OFC-Office Other Long-Term Debt Information Future maturities of the Company’s notes and bonds payable as of December 31, 2019 were as follows: Dollars in thousands PRINCIPAL MATURITIES NET ACCRETION/ AMORTIZATION 1 DEBT ISSUANCE COSTS 2 NOTES AND BONDS PAYABLE % 2020 $ 23,064 $ (392 ) $ (1,081 ) $ 21,591 1.5 % 2021 17,594 (326 ) (1,065 ) 16,203 1.1 % 2022 12,977 (336 ) (1,077 ) 11,564 0.8 % 2023 573,230 (183 ) (921 ) 572,126 40.5 % 2024 225,966 (262 ) (667 ) 225,037 15.9 % 2025 and thereafter 569,427 (849 ) (1,030 ) 567,548 40.2 % $ 1,422,258 $ (2,348 ) $ (5,841 ) $ 1,414,069 100.0 % 1 Includes discount accretion and premium amortization related to the Company’s Senior Notes due 2023, Senior Notes due 2025, Senior Notes due 2028 and 16 mortgage notes payable. 2 Excludes approximately $5.0 million in debt issuance costs related to the Company's Unsecured Credit Facility and Unsecured Term Loan due 2026 included in other assets, net.

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	Derivative Financial Instruments Risk Management Objective of Using Derivatives The Company is exposed to certain risks arising from both its business operations and economic conditions. The Company principally manages its exposures to a wide variety of business and operational risks through management of its core business activities. The Company manages economic risks, including interest rate, liquidity, and credit risk, primarily by managing the amount, sources, and duration of its assets and liabilities and the use of derivative financial instruments. Specifically, the Company enters into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known and uncertain cash amounts, the value of which are determined by interest rates. The Company’s derivative financial instruments are used to manage differences in the amount, timing, and duration of the Company’s known or expected cash receipts and its known or expected cash payments principally related to the Company’s borrowings. Cash Flow Hedges of Interest Rate Risk The Company’s objectives in using interest rate derivatives are to add stability to interest expense and to manage its exposure to interest rate movements. To accomplish this objective, the Company primarily uses interest rate swaps as part of its interest rate risk management strategy. Interest rate swaps designated as cash flow hedges involve the receipt of variable amounts from a counterparty in exchange for the Company making fixed-rate payments over the life of the agreements without exchange of the underlying notional amount. During 2019, 2018 and 2017, such derivatives were used to hedge the variable cash flows associated with existing variable-rate debt. 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 period(s) during which the hedged transaction affects earnings. Amounts reported in accumulated other comprehensive income (loss) related to derivatives will be reclassified to interest expense as interest payments are made on the Company’s variable-rate debt. The Company had eight outstanding interest rate derivatives that were designated as cash flow hedges of interest rate risk: INTEREST RATE DERIVATIVE NUMBER OF INSTRUMENTS NOTIONAL in millions Interest rate swaps - 2017 2 $ 25.0 Interest rate swaps - 2018 2 50.0 Interest rate swaps - 2019 4 100.0 Total interest rate swaps 8 $ 175.0 Tabular Disclosure of Fair Values of Derivative Instruments on the Balance Sheet The table below presents the fair value of the Company's derivative financial instruments, as well as, their classification on the Consolidated Balance Sheets as of December 31, 2019 and 2018 . AS OF DECEMBER 31, 2019 AS OF DECEMBER 31, 2018 Dollars in thousands BALANCE SHEET LOCATION FAIR VALUE BALANCE SHEET LOCATION FAIR VALUE Derivatives designated as hedging instruments Interest rate swaps 2017 Other liabilities $ (467 ) Other assets, net $ 229 Interest rate swaps 2018 Other liabilities (1,335 ) Other liabilities (68 ) Interest rate swaps 2019 Other liabilities (3,478 ) Other liabilities — Total derivatives designated as hedging instruments $ (5,280 ) $ 161 Tabular Disclosure of the Effect of Fair Value and Cash Flow Hedge Accounting on Accumulated Other Comprehensive Income (Loss) The table below presents the effect of cash flow hedge accounting on Accumulated other comprehensive income (loss) as of December 31, 2019 related to the Company's outstanding interest rate swaps. AMOUNT OF (LOSS) RECOGNIZED IN OCI on derivatives AMOUNT OF (GAIN)/LOSS RECLASSIFIED FROM OCI INTO INCOME for the twelve months ended December 31, Dollars in thousands 2019 2019 2018 Interest rate swaps 2017 $ (674 ) Interest expense $ (22 ) $ 51 Interest rate swaps 2018 (1,366 ) Interest expense 99 204 Interest rate swaps 2019 (3,552 ) Interest expense 74 — Settled interest rate swaps — Interest expense 168 169 $ (5,592 ) Total interest expense $ 319 $ 424 The Company estimates that an additional $1.4 million will be reclassified from accumulated other comprehensive loss as an increase to interest expense over the next 12 months. Tabular Disclosure Offsetting Derivatives The table below presents a gross presentation, the effects of offsetting, and a net presentation of the Company's derivatives as of December 31, 2019. The net amounts of derivative liabilities can be reconciled to the tabular disclosure of fair value. The tabular disclosure of fair value provides the location that derivative liabilities are presented on the Company's Consolidated Balance Sheets. Offsetting of Derivative Liabilities GROSS AMOUNTS of recognized liabilities GROSS AMOUNTS OFFSET in the Consolidated Balance Sheets NET AMOUNTS OF LIABILITIES presented in the Consolidated Balance Sheets GROSS AMOUNTS NOT OFFSET in the Consolidated Balance Sheets FINANCIAL INSTRUMENTS CASH COLLATERAL NET AMOUNT Derivatives $ (5,280 ) $ — $ (5,280 ) $ 5,280 $ — $ — 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. The Compa ny has agreements with each of its derivative counterparties that contain a provision where if the Company either defaults or is capable of being declared in default on any of its indebtedness, then the Company could also be declared in default on its derivative obligations. As of December 31, 2019, the fair value of derivatives in a net liability position including accrued interest but excluding any adjustment for nonperformance risk related to these agreements was $5.5 million . As of December 31, 2019, the Company has not posted any collateral related to these agreements and was not in breach of any agreement provisions. If the Company had breached any of these provisions, it could have been required to settle its obligations under the agreements at their aggregate termination value of $5.5 million .

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Stockholders' Equity	Stockholders’ Equity Common Stock The Company had no preferred shares outstanding and had common shares outstanding for the three years ended December 31, 2019 as follows: YEAR ENDED DECEMBER 31, 2019 2018 2017 Balance, beginning of year $ 125,279,455 $ 125,131,593 $ 116,416,900 Issuance of common stock 9,251,440 26,203 8,395,607 Non-vested share-based awards, net of withheld shares and forfeitures 175,259 121,659 319,086 Balance, end of year $ 134,706,154 $ 125,279,455 $ 125,131,593 Equity Offering On March 19, 2019, the Company issued 3,737,500 shares of common stock, par value $0.01 per share, at $ 31.40 per share in an underwritten public offering pursuant to the Company's existing effective registration statement. The net proceeds of the offering, after underwriting discounts and offering expenses, were approximately $115.8 million. At-The-Market Equity Offering Program The Company has in place an at-the-market equity offering program to sell shares of the Company’s common stock from time to time in at-the-market sales transactions. The following table details the shares sold under this program. SHARES SOLD SALE PRICE per share NET PROCEEDS in millions 2019 5,470,673 $32.01 - $33.77 $ 179.1 2018 — NA $ — 2017 — NA $ — The Company had 398,024 authorized shares remaining available to be sold under the current sales agreements as of January 31, 2020 and no shares were sold related to this program during 2017 or 2018. Dividends Declared During 2019 , the Company declared and paid common stock dividends aggregating $1.20 per share ( $0.30 per share per quarter). On February 11, 2020, the Company declared a quarterly common stock dividend in the amount of $0.30 per share payable on March 9, 2020 to stockholders of record on February 24, 2020. Authorization to Repurchase Common Stock On April 30, 2019, the Company’s Board of Directors authorized the repurchase of up to $50 million of outstanding shares of the Company’s common stock either in the open market or through privately negotiated transactions, subject to market conditions, regulatory constraints, and other customary conditions. The Company is not obligated under this authorization to repurchase any specific number of shares. This authorization supersedes all previous stock repurchase authorizations. As of the date of these Consolidated Financial Statements, the Company has not repurchased any shares of its common stock under this authorization. Accumulated Other Comprehensive Loss During each of the two years ended December 31, 2019 and 2018 , the Company entered into interest rate swaps to hedge the variable cash flows associated with existing variable-rate debt. The Company continues to amortize the 2015 settlement of forward-starting interest rate swaps. This amount will be reclassified out of accumulated other comprehensive loss impacting net income over the 10 -year term of the associated senior note issuance. See Note 10 for more information regarding the Company's derivative instruments. The following table represents the changes in accumulated other comprehensive loss during the years ended December 31, 2019 and 2018 : INTEREST RATE SWAPS as of December 31, Dollars in thousands 2019 2018 Beginning balance $ (902 ) $ (1,299 ) Other comprehensive loss before reclassifications 319 424 Amounts reclassified from accumulated other comprehensive income (loss) (5,592 ) (27 ) Net current-period other comprehensive (loss) income (5,273 ) 397 Ending balance $ (6,175 ) $ (902 ) The following table represents the details regarding the reclassifications from Accumulated other comprehensive income (loss) during the year ended December 31, 2019 (dollars in thousands): DETAILS ABOUT ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) COMPONENTS AMOUNT RECLASSIFIED from accumulated other comprehensive income (loss) AFFECTED LINE ITEM in the statement where net income is presented Amounts reclassified from accumulated other comprehensive income (loss) related to settled interest rate swaps $ 168 Interest Expense Amounts reclassified from accumulated other comprehensive income (loss) related to current interest rate swaps 151 Interest Expense $ 319

Stock and Other Incentive Plans

Stock and Other Incentive Plans	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Stock and Other Incentive Plans	Stock and Other Incentive Plans Stock Incentive Plan In May 2015, the Company's stockholders approved the 2015 Stock Incentive Plan which authorizes the Company to issue 3,500,000 shares of common stock to its employees and directors. The 2015 Incentive Plan, which superseded the 2007 Employee Stock Incentive Plan (the "Predecessor Plan"), will continue until terminated by the Company’s Board of Directors. As of December 31, 2019 and 2018 , the Company had issued a total of 1,988,079 and 1,711,240 restricted shares, respectively, under the 2015 Incentive Plan for compensation-related awards to employees and directors, with a total of 1,511,921 and 1,788,760 , respectively, remaining unissued under the plan. Under the Predecessor Plan for compensation-related awards to employees and directors, the Company had issued, net of forfeitures, a total of 1,878,637 restricted shares for the year ended December 31, 2015. Non-vested shares issued under the 2015 Incentive Plan are generally subject to fixed vesting periods varying from three to eight years beginning on the date of issue. If a recipient voluntarily terminates his or her relationship with the Company or is terminated for cause before the end of the vesting period, the shares are forfeited, at no cost to the Company. The Company recognizes the impact of forfeitures as they occur. Once the shares have been issued, the recipient has the right to receive dividends and the right to vote the shares. Compensation expense, included in general and administrative expense, recognized during the years ended December 31, 2019 , 2018 and 2017 from the amortization of the value of shares over the vesting period issued to employees and directors was $12.0 million , $10.4 million and $9.8 million , respectively. The Company's former Executive Chairman, David R. Emery, died on September 30, 2019 resulting in $2.9 million of expenses associated with the acceleration of his outstanding nonvested share-based awards. This charge is included in the 2019 compensation expense. In connection with the vesting, 80,490 shares were withheld to pay employee federal income taxes. T he following table represents expected amortization of the Company's non-vested shares issued: Dollars in millions FUTURE AMORTIZATION of non-vested shares 2020 $ 8.7 2021 7.3 2022 5.9 2023 3.8 2024 2.5 2025 and thereafter 1.9 Total $ 30.1 Executive Incentive Plan On July 31, 2012, the Company adopted an Executive Incentive Plan, which was amended and restated on February 16, 2016 ("Executive Incentive Plan"), to provide specific award criteria with respect to incentive awards made under the 2015 Incentive Plan subject to the discretion of the Compensation Committee. No new shares of common stock were authorized in connection with the Executive Incentive Plan. Under the terms of the Executive Incentive Plan, the Company's named executive officers, and certain other members of senior management, may earn incentive awards in the form of cash and non-vested stock. Cash incentive awards are based on individual and Company performance. Company performance is measured over a four-quarter period against targeted financial and operational metrics set in advance by the Compensation Committee. Non-vested stock awards are based on the Company's relative total shareholder return ("TSR") performance over one -year and three -year periods, measured against the Company's peer group. For 2019 , 2018 and 2017 , compensation expense, included in general and administrative expense, resulting from the amortization of non-vested share grants to officers was approximately $5.7 million , $5.7 million , and $5.0 million , respectively. Details of the awards that have been earned from this plan are as follows: • On December 12, 2019, the Company granted non-vested stock awards for TSR performance to its four named executive officers, five senior vice presidents, and five first vice presidents with a grant date fair value totaling $6.1 million , which were granted in the form of 187,072 non-vested shares, with a five -year vesting period, which will result in annual compensation expense of $1.2 million for the each of 2020, 2021, 2022, and 2023, and $1.1 million for 2024, respectively. • On December 12, 2018, the Company granted non-vested stock awards for TSR performance to its four named executive officers and five senior vice presidents with a grant date fair value totaling $5.0 million , which were granted in the form of 165,261 non-vested shares, with a five -year vesting period, which will result in annual compensation expense of $1.0 million for the each of 2019, 2020, 2021, and 2022, and $0.9 million for 2023, respectively. • On December 11, 2017, the Company granted non-vested stock awards for TSR performance to its five named executive officers and four senior vice presidents with a grant date fair value totaling $10.1 million , which were granted in the form of 309,874 non-vested shares, with a five -year vesting period, which will result in annual compensation expense of $2.0 million for the each of 2019, 2020, and 2021, and $1.9 million for 2022, respectively. Long-Term Incentive Program In the first quarter of 2019 and 2018 , the Company granted a performance-based award to officers, excluding the four named executive officers and five senior vice presidents, under the Long-term Incentive Program adopted under the 2015 Incentive Plan (the "LTIP") totaling approximately $1.0 million and $1.2 million , which was granted in the form of 31,262 non-vested shares and 43,414 non-vested shares, respectively. The shares have vesting periods ranging from three to eight years with a weighted average vesting period of approximately six years. For 2019 , 2018 and 2017 , compensation expense resulting from the amortization of non-vested share grants to officers was approximately $1.1 million , $1.2 million , and $1.1 million , respectively. Salary Deferral Plan The Company's salary deferral plan allows certain of its officers to elect to defer up to 50% of their base salary in the form of non-vested shares issued under the 2015 Incentive Plan subject to long-term vesting. The number of shares will be increased through a Company match depending on the length of the vesting period selected by the officer. The officer's vesting period choices are: three years for a 30% match; five years for a 50% match; and eight years for a 100% match. During 2019 , 2018 and 2017 , the Company issued 33,509 shares, 33,348 shares and 39,016 shares, respectively, to its officers through the salary deferral plan. For 2019 , 2018 and 2017 , compensation expense resulting from the amortization of non-vested share grants to officers was approximately $0.9 million , $1.0 million , and $1.2 million , respectively. Non-employee Directors Incentive Plan The Company issues non-vested shares to its non-employee directors under the 2015 Incentive Plan. The directors’ shares issued have a one -year vesting period beginning with the May 2015 grant (previously a three -year vesting period) and are subject to forfeiture prior to such date upon termination of the director’s service, at no cost to the Company. During 2019 , 2018 and 2017 , the Company issued 24,996 shares, 30,989 shares, and 23,231 shares, respectively, to its non-employee directors through the 2015 Incentive Plan. For each of the years 2019 , 2018 and 2017 , compensation expense resulting from the amortization of non-vested share grants to directors was approximately $0.8 million , respectively. Other Grants The Company issued three one-time non-vested share grants related to executive management transition in 2016. For 2019 , 2018 and 2017 compensation expense resulting from the amortization of these non-vested share grants to officers was approximately $3.5 million , $1.7 million , and $1.7 million , respectively. The following information provides information about each grant: • On March 1, 2016, the Company issued 50,000 shares to the Chief Financial Officer with a 10 -year vesting period, resulting in compensation expense of $0.2 million per year. • On December 30, 2016, the Company issued 200,000 shares to the President and Chief Executive Officer with a 10 -year vesting period, resulting in compensation expense of $0.6 million per year. • On December 30, 2016, the Company issued 150,000 shares to the Executive Chairman with a 5 -year vesting period, resulting in compensation expense of $0.9 million per year. The Company's former Executive Chairman, David R. Emery, died on September 30, 2019 resulting in the acceleration of this outstanding grant totaling $2.0 million . A summary of the activity under the 2015 Incentive Plan and related information for the three years in the period ended December 31, 2019 follows: YEAR ENDED DECEMBER 31, Dollars in thousands, except per share data 2019 2018 2017 Share-based awards, beginning of year 1,769,863 1,907,645 1,786,497 Granted 276,839 273,012 413,489 Vested (292,636 ) (410,794 ) (292,341 ) Share-based awards, end of year 1,754,066 1,769,863 1,907,645 Weighted-average grant date fair value of Share-based awards, beginning of year $ 29.36 $ 28.44 $ 27.18 Share-based awards granted during the year $ 31.75 $ 29.72 $ 32.05 Share-based awards vested during the year $ 28.84 $ 25.32 $ 25.88 Share-based awards, end of year $ 29.82 $ 29.36 $ 28.44 Grant date fair value of shares granted during the year $ 8,791 $ 8,114 $ 13,254 The vesting periods for the non-vested shares granted during 2019 ranged from one to eight years with a weighted-average amortization period remaining as of December 31, 2019 of approximately 5 years. During 2019 , 2018 and 2017 , the Company withheld 101,580 shares, 151,353 shares and 94,403 shares, respectively, of common stock from its officers to pay estimated withholding taxes related to the vesting of shares. 401(k) Plan The Company maintains a 401(k) plan that allows eligible employees to defer salary, subject to certain limitations imposed by the Internal Revenue Code. The Company provides a matching contribution of up to 3% of each eligible employee’s salary, subject to certain limitations. The Company’s matching contributions were approximately $0.5 million for the year ended December 31, 2019 and $0.4 million for each year during 2018 and 2017 . Dividend Reinvestment Plan The Company is authorized to issue 1,000,000 shares of common stock to stockholders under the Dividend Reinvestment Plan. As of December 31, 2019 , the Company had issued 599,104 shares under the plan of which 7,990 shares were issued in 2019 , 9,487 shares were issued in 2018 and 26,031 shares were issued in 2017 . Employee Stock Purchase Plan The Company has an Employee Stock Purchase Plan, pursuant to which the Company is authorized to issue shares of common stock. Under the Employee Stock Purchase Plan, each eligible employee in January of each year is able to purchase up to $25,000 of common stock at the lesser of 85% of the market price on the date of grant or 85% of the market price on the date of exercise of such option. The number of shares subject to each year’s option becomes fixed on the date of grant. Options granted under the Employee Stock Purchase Plan expire if not exercised 27 months after each such option’s date of grant. The Company accounts for these awards based on fair value, using the Black-Scholes model, and generally recognizes expense over the award’s vesting period, net of forfeitures. Since the options granted under the Employee Stock Purchase Plan immediately vest, the Company records compensation expense for those options when they are granted in the first quarter of each year and then may record additional compensation expense in subsequent quarters as warranted. During the years ended December 31, 2019 , 2018 and 2017 , the Company recognized in general and administrative expenses approximately $0.2 million , $0.3 million , and $0.2 million , respectively, of compensation expense related to the annual grant of options to its employees to purchase shares under the Employee Stock Purchase Plan. Cash received from employees upon exercising options under the Employee Stock Purchase Plan was approximately $1.0 million for the year ended December 31, 2019 , $0.4 million for the year ended December 31, 2018 , and $0.8 million for the year ended December 31, 2017 . A summary of the Employee Stock Purchase Plan activity and related information for the three years in the period ended December 31, 2019 is as follows: YEAR ENDED DECEMBER 31, Dollars in thousands, except per share data 2019 2018 2017 Options outstanding, beginning of year 328,533 318,100 316,321 Granted 235,572 203,836 206,824 Exercised (35,277 ) (16,716 ) (32,076 ) Forfeited (54,095 ) (40,897 ) (40,659 ) Expired (142,074 ) (135,790 ) (132,310 ) Options outstanding and exercisable, end of year 332,659 328,533 318,100 Weighted-average exercise price of Options outstanding, beginning of year $ 24.17 $ 25.00 $ 23.69 Options granted during the year $ 24.17 $ 27.30 $ 25.77 Options exercised during the year $ 25.01 $ 24.01 $ 24.31 Options forfeited during the year $ 25.26 $ 24.06 $ 25.01 Options expired during the year $ 25.77 $ 23.55 $ 23.22 Options outstanding, end of year $ 25.59 $ 24.17 $ 25.00 Weighted-average fair value of options granted during the year (calculated as of the grant date) $ 7.02 $ 7.81 $ 6.31 Intrinsic value of options exercised during the year $ 269 $ 71 $ 271 Intrinsic value of options outstanding and exercisable (calculated as of December 31) $ 2,589 $ 1,402 $ 2,683 Exercise prices of options outstanding (calculated as of December 31) $ 25.59 $ 24.17 $ 25.00 Weighted-average contractual life of outstanding options (calculated as of December 31, in years) 0.8 0.8 0.8 The fair values for these options were estimated at the date of grant using a Black-Scholes options pricing model with the weighted-average assumptions for the options granted during the period noted in the following table. The risk-free interest rate was based on the U.S. Treasury constant maturity-nominal two-year rate whose maturity is nearest to the date of the expiration of the latest option outstanding and exercisable; the expected dividend yield was based on the expected dividends of the current year as a percentage of the average stock price of the prior year; the expected life of each option was estimated using the historical exercise behavior of employees; expected volatility was based on historical volatility of the Company’s common stock; and expected forfeitures were based on historical forfeiture rates within the look-back period. 2019 2018 2017 Risk-free interest rates 2.48 % 1.89 % 1.20 % Expected dividend yields 4.19 % 3.66 % 3.70 % Expected life (in years) 1.45 1.45 1.45 Expected volatility 29.8 % 28.4 % 20.4 % Expected forfeiture rates 85 % 85 % 85 %

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Earnings Per Share	Earnings Per Share The Company uses the two-class method of computing net earnings per common share. Non-vested share-based awards containing non-forfeitable rights to dividends are considered participating securities pursuant to the two-class method. The table below sets forth the computation of basic and diluted earnings per common share for the three years in the period ended December 31, 2019 . YEAR ENDED DECEMBER 31, Dollars in thousands, except per share data 2019 2018 2017 Weighted average common shares Weighted average common shares outstanding 129,735,723 125,219,773 119,739,216 Non-vested shares (1,736,022 ) (1,927,648 ) (1,813,058 ) Weighted average common shares - basic 127,999,701 123,292,125 117,926,158 Weighted average common shares - basic 127,999,701 123,292,125 117,926,158 Dilutive effect of employee stock purchase plan 84,283 58,808 91,007 Weighted average common shares - diluted 128,083,984 123,350,933 118,017,165 Net income $ 39,185 $ 69,771 $ 23,092 Dividends paid on nonvested share-based awards (2,075 ) (2,320 ) (2,149 ) Net income applicable to common stockholders $ 37,110 $ 67,451 $ 20,943 Basic earnings per common share $ 0.29 $ 0.55 $ 0.18 Diluted earnings per common share $ 0.29 $ 0.55 $ 0.18

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Redevelopment Activity The Company completed the redevelopment of a medical office building in Charlotte, North Carolina, which includes a 40,278 square foot vertical expansion and funded approximately $1.5 million during the year ended December 31, 2019 . The first tenant took occupancy in the second quarter of 2019. The Company initiated the redevelopment of a 110,883 square foot medical office building in Memphis, Tennessee in December 2019. The Company funded approximately $0.3 million , excluding the purchase price of $8.7 million for the land and building. The building will continue to operate with in-place leases during construction. The Memphis Redevelopment is expected to be completed in the first quarter of 2021. The Company also funded approximately $1.0 million of primarily tenant improvements in connection with its previously completed redevelopment of a medical office building in Nashville, Tennessee. Development Activity The Company continued the development of a 151,000 square foot medical office building in Seattle, Washington. The Company spent approximately $25.2 million on the development during the year ended December 31, 2019 . The Company expects initial occupancy to occur in the first quarter of 2020. The Company also funded approximately $0.6 million of primarily tenant improvements as the Company continues to lease up its previously completed development of a medical office building in Denver, Colorado. The table below details the Company’s construction activity as of December 31, 2019 . The information included in the table below represents management’s estimates and expectations at December 31, 2019 , which are subject to change. The Company’s disclosures regarding certain projections or estimates of completion dates may not reflect actual results. DECEMBER 31, 2019 ESTIMATED REMAINING FUNDINGS unaudited ESTIMATED TOTAL INVESTMENT unaudited APPROXIMATE SQUARE FEET unaudited Dollars in thousands NUMBER OF PROPERTIES INITIAL OCCUPANCY CONSTRUCTION IN PROGRESS BALANCE TOTAL FUNDED during the year TOTAL AMOUNT FUNDED Construction Activity Seattle, WA 1 Q1 2020 $ 48,731 $ 25,211 $ 49,033 $ 15,087 $ 64,120 151,000 Redevelopment Activity Memphis, TN 1 1 Q1 2021 — 9,032 9,032 18,768 27,800 110,883 Total $ 48,731 $ 34,243 $ 58,065 $ 33,855 $ 91,920 261,883 1 Initial occupancy represents the quarter in which the redevelopment is expected to be completed. The building will continue to operate with in-place leases during construction. Tenant Improvements The Company may provide a tenant improvement allowance in new or renewal leases for the purpose of refurbishing or renovating tenant space. As of December 31, 2019 , the Company had commitments of approximately $46.6 million that are expected to be spent on tenant improvements throughout the portfolio, excluding development properties currently under construction. Land Held for Development Land held for development includes parcels of land owned by the Company, upon which the Company intends to develop and own outpatient healthcare facilities. The Company’s investment in seven parcels of land held for development located adjacent to certain of the Company's existing medical office buildings in Texas, Iowa, Tennessee and Colorado totaled approximately $24.6 million as of December 31, 2019 and December 31, 2018

Other Data

Other Data	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Other Data	Other Data Taxable Income (unaudited) The Company has elected to be taxed as a REIT, as defined under the Internal Revenue Code. To qualify as a REIT, the Company must meet a number of organizational and operational requirements, including a requirement that it currently distribute at least 90% of its taxable income to its stockholders. As a REIT, the Company generally will not be subject to federal income tax on taxable income it distributes currently to its stockholders. Accordingly, no provision for federal income taxes has been made in the accompanying Consolidated Financial Statements. If the Company fails to qualify as a REIT for any taxable year, then it will be subject to federal income taxes at regular corporate rates, including any applicable alternative minimum tax, and may not be able to qualify as a REIT for four subsequent taxable years. Even if the Company qualifies as a REIT, it may be subject to certain state and local taxes on its income and property and to federal income and excise tax on its undistributed taxable income. Earnings and profits (as defined under the Internal Revenue Code), the current and accumulated amounts of which determine the taxability of distributions to stockholders, vary from net income attributable to common stockholders and taxable income because of different depreciation recovery periods, depreciation methods, and other items. On a tax-basis, the Company’s gross real estate assets totaled approximately $4.4 billion , $4.0 billion , and $4.0 billion as of December 31, 2019 , 2018 and 2017, respectively. The following table reconciles the Company’s consolidated net income attributable to common stockholders to taxable income for the three years ended December 31, 2019 : YEAR ENDED DECEMBER 31, Dollars in thousands 2019 2018 2017 Net income $ 39,185 $ 69,771 $ 23,092 Reconciling items to taxable income Depreciation and amortization 67,953 64,775 46,426 Gain or loss on disposition of depreciable assets (15,689 ) (27,581 ) 1,570 Straight-line rent (11,535 ) (3,049 ) (4,551 ) Receivable allowances 1,942 2,470 1,680 Share-based compensation 2,628 (1,699 ) 1,855 Other 12,631 842 6,552 57,930 35,758 53,532 Taxable income 1 $ 97,115 $ 105,529 $ 76,624 Dividends paid $ 155,358 $ 150,266 $ 142,327 1 Before REIT dividend paid deduction. Characterization of Distributions (unaudited) Distributions in excess of earnings and profits generally constitute a return of capital. The following table gives the characterization of the distributions on the Company’s common stock for the three years ended December 31, 2019 . For the three years ended December 31, 2019 , there were no preferred shares outstanding. As such, no dividends were distributed related to preferred shares for those periods. 2019 2018 2017 PER SHARE % PER SHARE % PER SHARE % Common stock Ordinary income 1 $ 0.79 65.7 % $ 0.75 62.2 % $ 0.42 34.5 % Return of capital 0.40 33.9 % 0.33 27.8 % 0.50 42.0 % Unrecaptured section 1250 gain 0.01 0.4 % 0.12 10.0 % 0.28 23.5 % Common stock distributions $ 1.20 100.0 % $ 1.20 100.0 % $ 1.20 100.0 % 1 For the 2018 reporting year all ordinary income is also Code Section 199A eligible per the The Tax Cut and Jobs Act of 2017. State Income Taxes The Company must pay certain state income taxes, which are typically included in general and administrative expense on the Company’s Consolidated Statements of Income. The State of Texas gross margins tax on gross receipts from operations is disclosed in the table below as an income tax because it is considered such by the Securities and Exchange Commission. State income tax expense and state income tax payments for the three years ended December 31, 2019 are detailed in the table below: YEAR ENDED DECEMBER 31, Dollars in thousands 2019 2018 2017 State income tax expense Texas gross margins tax $ 550 $ 586 $ 608 Total state income tax expense $ 550 $ 586 $ 608 State income tax payments, net of refunds and collections $ 543 $ 637 $ 555

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The following methods and assumptions were used to estimate the fair value of each class of financial instrument for which it is practical to estimate that value. • Cash, cash equivalents and restricted cash - The carrying amount approximates fair value. • Borrowings under the Unsecured Credit Facility, Unsecured Term Loan due 2024 and Unsecured Term Loan due 2026 - The carrying amount approximates fair value because the borrowings are based on variable market interest rates. • Senior unsecured notes payable - The fair value of notes and bonds payable is estimated using cash flow analyses, based on the Company’s current interest rates for similar types of borrowing arrangements. • Mortgage notes payable - The fair value is estimated using cash flow analyses, based on the Company’s current interest rates for similar types of borrowing arrangements. • Interest rate swap agreements - Interest rate swap agreements are recorded in other liabilities on the Company's Consolidated Balance Sheets at fair value. Fair value is estimated by utilizing pricing models that consider forward yield curves and discount rates. The table below details the fair value and carrying values for notes and bonds payable as of December 31, 2019 and 2018 . DECEMBER 31, 2019 DECEMBER 31, 2018 Dollars in millions CARRYING VALUE FAIR VALUE CARRYING VALUE FAIR VALUE Notes and bonds payable 1 $ 1,414.1 $ 1,425.8 $ 1,346.0 $ 1,326.5 1 Level 2 – model-derived valuations in which significant inputs and significant value drivers are observable in active markets.

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2019
Selected Quarterly Financial Information [Abstract]
Selected Quarterly Financial Data (unaudited)	Selected Quarterly Financial Data (unaudited) Quarterly financial information for the year ended December 31, 2019 is summarized below. QUARTER ENDED Dollars in thousands, except per share data MARCH 31 JUNE 30 SEPTEMBER 30 DECEMBER 31 1 2019 Revenues $ 112,657 $ 116,317 $ 119,799 $ 121,524 Net income attributable to common stockholders $ 4,891 $ 4,484 $ 2,601 $ 27,210 Net income attributable to common stockholders per share Basic earnings per common share $ 0.04 $ 0.03 $ 0.02 $ 0.20 Diluted earnings per common share $ 0.04 $ 0.03 $ 0.02 $ 0.20 1 The increases in net income and amounts per share for the fourth quarter of 2019 are primarily attributable to gains of $20.0 million on the sale of six properties. Quarterly financial information for the year ended December 31, 2018 is summarized below. QUARTER ENDED Dollars in thousands, except per share data MARCH 31 JUNE 30 1 SEPTEMBER 30 DECEMBER 31 2 2018 Revenues $ 112,124 $ 111,634 $ 113,462 $ 113,168 Net income attributable to common stockholders $ 9,180 $ 37,729 $ 6,548 $ 16,314 Net income attributable to common stockholders per share Basic earnings per common share $ 0.07 $ 0.30 $ 0.05 $ 0.13 Diluted earnings per common share $ 0.07 $ 0.30 $ 0.05 $ 0.13 1 The increases in net income and amounts per share for the second quarter of 2018 are primarily attributable to gains of $27.7 million on the sale of twelve properties. 2 The increases in net income and amounts per share for the fourth quarter of 2018 are primarily attributable to gains of $10.8 million on the sale of three

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	Schedule II – Valuation and Qualifying Accounts for the years ended December 31, 2019 , 2018 and 2017 Dollars in thousands ADDITIONS AND DEDUCTIONS DESCRIPTION BALANCE AT BEGINNING OF PERIOD CHARGED/(CREDITED) TO COSTS AND EXPENSES CHARGED TO OTHER ACCOUNTS UNCOLLECTIBLE ACCOUNTS WRITTEN-OFF BALANCE AT END OF PERIOD 2019 Accounts receivable allowance $ 251 $ 167 $ — $ — $ 418 2018 Accounts receivable allowance $ 256 $ 60 $ — $ 65 $ 251 2017 Accounts receivable allowance $ 148 $ 159 $ — $ 51 $ 256

Schedule III - Real Estate and

Schedule III - Real Estate and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2019
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Real Estate and Accumulated Depreciation	Schedule III – Real Estate and Accumulated Depreciation as of December 31, 2019 Dollars in thousands LAND 1 BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1 MARKET NUMBER OF PROP. INITIAL INVESTMENT COST CAPITALIZED subsequent to acquisition TOTAL INITIAL INVESTMENT COST CAPITALIZED subsequent to acquisition TOTAL PERSONAL PROPERTY 2, 3, 5 TOTAL PROPERTY 1, 3 ACCUMULATED DEPRECIATION 4 ENCUMBRANCES DATE ACQUIRED DATE CONST. Seattle, WA 25 $ 54,446 $ 4,119 $ 58,565 $ 490,461 $ 42,306 $ 532,767 $ 421 $ 591,753 $ 88,890 $ 22,666 2008-2019 1957-2010 Dallas, TX 25 18,785 409 19,194 372,644 124,039 496,683 442 516,319 181,556 — 2003-2019 1974-2018 Los Angeles, CA 14 43,719 667 44,386 161,322 44,507 205,829 347 250,562 95,979 22,340 1993-2019 1973-1998 Atlanta, GA 9 3,251 428 3,679 209,400 3,109 212,509 84 216,272 20,040 31,715 2017-2019 1999-2014 Nashville, TN 6 20,004 49 20,053 115,061 65,402 180,463 1,109 201,625 64,038 — 2004-2018 1960-2015 Charlotte, NC 16 4,163 37 4,200 159,340 16,921 176,261 105 180,566 67,040 — 2008-2013 1961-2008 Denver, CO 9 13,887 2,627 16,514 106,183 27,821 134,004 271 150,789 25,265 7,565 2010-2018 1977-2015 Washington, DC 6 — — — 141,467 8,837 150,304 21 150,325 25,097 11,707 2004-2019 1967-2005 Richmond, VA 7 — — — 139,636 9,496 149,132 106 149,238 44,204 — 2011 1992-2005 Houston, TX 9 15,475 736 16,211 107,902 24,111 132,013 78 148,302 44,229 — 1993-2019 1984-2012 Honolulu, HI 3 8,314 13 8,327 93,839 41,802 135,641 159 144,127 39,165 — 2003-2004 1975-2010 Des Moines, IA 7 12,584 81 12,665 114,527 11,874 126,401 99 139,165 34,725 515 2008-2014 2002-2009 Oklahoma, City, OK 4 9,838 563 10,401 114,212 1,494 115,706 15 126,122 19,351 5,985 2010-2019 1970-2014 Indianapolis, IN 4 3,299 — 3,299 112,718 6,129 118,847 — 122,146 26,082 — 2008-2019 1992-2008 San Francisco, CA 3 14,054 — 14,054 93,852 13,544 107,396 43 121,493 20,906 — 2015-2017 1975-2014 Springfield, MO 1 1,989 — 1,989 109,304 — 109,304 — 111,293 17,740 — 2013 2013 Austin, TX 5 14,233 3 14,236 70,976 21,833 92,809 123 107,168 24,048 — 2007-2015 1972-2015 Memphis, TN 7 5,241 — 5,241 66,868 25,640 92,508 194 97,943 37,582 — 1999-2013 1993-2007 San Antonio, TX 6 6,456 31 6,487 62,161 26,422 88,583 404 95,474 40,573 — 1996-2010 1978-2011 Chicago, IL 3 5,859 — 5,859 69,993 17,595 87,588 211 93,658 23,540 — 2004-2018 1993-2009 Minneapolis, MN 4 2,090 — 2,090 61,078 1,281 62,359 — 64,449 10,486 18,907 2014-2017 1974-2010 Other (16 markets) 31 16,434 645 17,079 388,102 87,307 475,409 806 493,294 165,159 7,943 1993-2019 1906-2009 Total real estate 204 274,121 10,408 284,529 3,361,046 621,470 3,982,516 5,038 4,272,083 1,115,695 129,343 Construction in progress — — — — — — 48,731 — 48,731 — Land held for develop. — 24,647 — 24,647 — — — — 24,647 671 — Memphis redevelopment — 5,222 — 5,222 3,810 — 3,810 — 9,032 50 — Corporate property — — — — — — — 5,500 5,500 4,686 — Total properties 204 $ 303,990 $ 10,408 $ 314,398 $ 3,364,856 $ 621,470 $ 4,035,057 $ 10,538 $ 4,359,993 $ 1,121,102 $ 129,343 1 The Company had no assets held for sale as of December 31, 2019. 2 Total properties as of December 31, 2019 have an estimated aggregate total cost of $4.4 billion for federal income tax purposes. 3 Depreciation is provided for on a straight-line basis on buildings and improvements over 3.3 to 39.0 years , lease intangibles over 2.1 to 99.0 years , personal property over 2.8 to 20.0 years, and land improvements over 3.0 to 39.0 years. 4 Includes unamortized premium of $1.2 million and unaccreted discount of $0.5 million and issuance costs of $0.5 million as of December 31, 2019 . 5 Rollforward of Total Property and Accumulated Depreciation, including assets held for sale, for the year ended December 31, 2019 , 2018 and 2017 follows: YEAR ENDED DEC. 31, 2019 YEAR ENDED DEC. 31, 2018 YEAR ENDED DEC. 31, 2017 Dollars in thousands TOTAL PROPERTY ACCUMULATED DEPRECIATION TOTAL PROPERTY ACCUMULATED DEPRECIATION TOTAL PROPERTY ACCUMULATED DEPRECIATION Beginning Balance $ 3,993,427 $ 1,025,831 $ 3,907,010 $ 933,220 $ 3,633,993 $ 843,816 Additions during the period Real Estate acquired 384,762 9,285 112,591 4,175 322,616 4,206 Other improvements 71,666 165,367 74,317 157,385 59,442 135,807 Land held for development — 278 4,525 153 — 74 Construction in Progress 15,625 — 27,649 — 14,598 — Retirement/dispositions Real Estate (105,487 ) (79,659 ) (132,665 ) (69,102 ) (123,639 ) (50,683 ) Land held for development — — — — — Ending Balance $ 4,359,993 $ 1,121,102 $ 3,993,427 $ 1,025,831 $ 3,907,010 $ 933,220 All other schedules for which provision is made in the applicable accounting regulations of the Securities and Exchange Commission are omitted because they are not required under the related instructions or are not applicable, or because the required information is shown in the consolidated financial statements or notes thereto.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Business Overview	Business Overview Healthcare Realty Trust Incorporated (the “Company”) is a real estate investment trust ("REIT") that owns, leases, manages, acquires, finances, develops and redevelops income-producing real estate properties associated primarily with the delivery of outpatient healthcare services throughout the United States of America. The Company had gross investments of approximately $4.4 billion in 204 real estate properties, construction in progress, the Memphis Redevelopment, land held for development and corporate property as of December 31, 2019 . The Company’s 204 owned real estate properties are located in 25 states and total approximately 15.4 million square feet. The Company provided property management services to approximately 11.4 million square feet nationwide. Square footage and property count disclosures in these Notes to the Company's Consolidated Financial Statements are unaudited.
Principles of Consolidation	Principles of Consolidation The Company’s Consolidated Financial Statements include the accounts of the Company, its wholly owned subsidiaries, joint ventures, and partnerships where the Company controls the operating activities. The Company's investments in its unconsolidated joint ventures are included in other assets and the related equity income is recognized within interest and other income (expense), net in other income (expense) on the Company's Consolidated Financial Statements. See Note 7 for additional information. All significant intercompany accounts, transactions and balances have been eliminated upon consolidation in the Consolidated Financial Statements.
Use of Estimates in the Consolidated Financial Statements	Use of Estimates in the Consolidated Financial Statements Preparation of the Consolidated Financial Statements in accordance with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect amounts reported in the Consolidated Financial Statements and accompanying notes. Actual results may differ from those estimates.
Segment Reporting	Segment Reporting The Company owns, leases, acquires, manages, finances, develops and redevelops outpatient and other healthcare-related properties. The Company is managed as one reporting unit, rather than multiple reporting units, for internal reporting purposes and for internal decision-making. Therefore, the Company discloses its operating results in a single reportable segment.
Real Estate Properties	Real Estate Properties Real estate properties are recorded at cost or at fair value if acquired in a transaction that is a business combination under Accounting Standards Codification Topic 805, Business Combinations . Cost or fair value at the time of acquisition is allocated among land, buildings, tenant improvements, lease and other intangibles, and personal property as applicable. The Company’s gross real estate assets, on a financial reporting basis, totaled approximately $4.4 billion as of December 31, 2019 and $4.0 billion as of December 31, 2018 . During 2019 and 2018 , the Company eliminated against accumulated depreciation approximately $17.2 million and $9.9 million , respectively, of fully amortized real estate intangibles that were initially recorded as a component of certain real estate acquisitions. Also during 2019 and 2018 , approximately $1.3 million and $0.5 million of fully depreciated tenant and capital improvements that were no longer in service were eliminated against accumulated depreciation. Depreciation expense of real estate properties for the three years ended December 31, 2019, 2018 and 2017 was $152.6 million , $143.8 million and $129.4 million , respectively. Depreciation and amortization of real estate assets and liabilities in place as of December 31, 2019 , is provided for on a straight-line basis over the asset’s estimated useful life: Land improvements 3.0 to 39.0 years Buildings and improvements 3.3 to 39.0 years Lease intangibles (including ground lease intangibles) 2.1 to 99.0 years Personal property 2.8 to 20.0 years The Company capitalizes direct costs, including costs such as construction costs and professional services, and indirect costs, including capitalized interest and overhead costs, associated with the development and construction of real estate assets while substantive activities are ongoing to prepare the assets for their intended use. Capitalized interest cost is calculated using the weighted average interest rate of the Company's unsecured debt or the interest rate on project specific debt, if applicable. The Company continues to capitalize interest on the unoccupied portion of the properties in stabilization for up to one year after the buildings have been placed into service, at which time the capitalization of interest must cease.
Land Held for Development	Land Held for Development
Asset Impairment	Asset Impairment The Company assesses the potential for impairment of identifiable, definite-lived, intangible assets and long-lived assets, including real estate properties, whenever events occur or a change in circumstances indicates that the carrying value might not be fully recoverable. Indicators of impairment may include significant underperformance of an asset relative to historical or expected operating results; significant changes in the Company’s use of assets or the strategy for its overall business; plans to sell an asset before its depreciable life has ended; the expiration of a significant portion of leases in a property; or significant negative economic trends or negative industry trends for the Company or its operators. In addition, the Company reviews for possible impairment, those assets subject to purchase options and those impacted by casualties, such as tornadoes and hurricanes. If management determines that the carrying value of the Company’s assets may not be fully recoverable based on the existence of any of the factors above, or others, management would measure and record an impairment charge based on the estimated fair value of the property or the estimated fair value less costs to sell the property.
Acquisitions of Real Estate Properties with In-Place Leases	Acquisitions of Real Estate Properties with In-Place Leases The Company's acquisitions of real estate properties typically do not meet the definition of a business and are accounted for as asset acquisitions. Acquisitions of real estate properties with in-place leases are accounted for at relative fair value. When a building with in-place leases is acquired, the cost of the acquisition must be allocated between the tangible real estate assets "as-if-vacant" and the intangible real estate assets related to in-place leases based on their estimated fair values. Land fair value is estimated by using an assessment of comparable transactions and other relevant data. The values related to above- or below-market in-place lease intangibles are amortized over the remaining term of the leases upon acquisition to rental income where the Company is the lessor and to property operating expense where the Company is the lessee. The Company considers whether any of the in-place lease rental rates are above- or below-market. An asset (if the actual rental rate is above-market) or a liability (if the actual rental rate is below-market) is calculated and recorded in an amount equal to the present value of the future cash flows that represent the difference between the actual lease rate and the estimated market rate. If an in-place lease is identified as a below-market rental rate, the Company would also evaluate any renewal options associated with that lease to determine if the intangible should include those periods. The Company also estimates an absorption period, which can vary by property, assuming the building is vacant and must be leased up to the actual level of occupancy when acquired. During that absorption period, the owner would incur direct costs, such as tenant improvements, and would suffer lost rental income. Likewise, the owner would have acquired a measurable asset in that, assuming the building was vacant, certain fixed costs would be avoided because the actual in-place lessees would reimburse a certain portion of fixed costs through expense reimbursements during the absorption period. All of these intangible assets (above- or below-market lease, tenant improvement costs avoided, leasing costs avoided, rental income lost, and expenses recovered through in-place lessee reimbursements) are estimated and recorded in amounts equal to the present value of estimated future cash flows. The actual purchase price is allocated based on the various asset fair values described above. The building and tenant improvement components of the purchase price are depreciated over the estimated useful life of the building or the weighted average remaining term of the in-places leases. The at-market, in-place lease intangibles are amortized to amortization expense over the weighted average remaining term of the leases, customer relationship assets are amortized to amortization expense over terms applicable to each acquisition. Any goodwill recorded through a business combination would be reviewed for impairment at least annually and is not amortized.
Fair Value Measurements	Fair Value Measurements Fair value is defined as the price that would be received to sell an asset, or paid to transfer a liability, in an orderly transaction between market participants. In calculating fair value, a company must maximize the use of observable market inputs, minimize the use of unobservable market inputs and disclose in the form of an outlined hierarchy the details of such fair value measurements. A hierarchy of valuation techniques is defined to determine whether the inputs to a fair value measurement are considered to be observable or unobservable in a marketplace. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect the Company’s market assumptions. This hierarchy requires the use of observable market data when available. These inputs have created the following fair value hierarchy: • Level 1 – quoted prices for identical instruments in active markets; • Level 2 – quoted prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which significant inputs and significant value drivers are observable in active markets; and • Level 3 – fair value measurements derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. Executed purchase and sale agreements, that are binding agreements, are categorized as level one inputs. Brokerage estimates, letters of intent, or unexecuted purchase and sale agreements are considered to be level three as they are nonbinding in nature.
Fair Value of Derivative Financial Instruments	Fair Value of Derivative Financial Instruments Derivative financial instruments are recorded at fair value on the Company's Consolidated Balance Sheets as other assets or other liabilities. The valuation of derivative instruments requires the Company to make estimates and judgments that affect the fair value of the instruments. Fair values of derivatives are estimated by pricing models that consider the forward yield curves and discount rates. The fair value of the Company's forward starting interest rate swap contracts are estimated by pricing models that consider foreign trade rates and discount rates. Such amounts and the recognition of such amounts are subject to significant estimates that may change in the future. For derivatives designated in qualifying cash flow hedging relationships, the change in fair value of the effective portion of the derivatives is recognized in accumulated other comprehensive income (loss). Gains and losses are reclassified from accumulated other comprehensive income (loss) into earnings once the underlying hedged transaction is recognized in earnings. As of December 31, 2019 and 2018, the Company had $6.2 million and $0.9 million
Cash, Cash Equivalents and Restricted Cash	Cash, Cash Equivalents and Restricted Cash Cash and cash equivalents includes short-term investments with original maturities of three months or less when purchased. Restricted cash includes cash held in escrow in connection with proceeds from the sales of certain real estate properties. The Company did not have any restricted cash for the year ended December 31, 2019. The Company had restricted cash during the year ended December 31, 2018, however it was reinvested for real estate acquisitions prior to the ending balance sheet date.
Goodwill and Other Intangible Assets	Goodwill and Other Intangible Assets Goodwill and intangible assets with indefinite lives are not amortized, but are tested at least annually for impairment. Intangible assets with finite lives are amortized over their respective lives to their estimated residual values and are reviewed for impairment only when impairment indicators are present. Identifiable intangible assets of the Company are comprised of enterprise goodwill, in-place lease intangible assets, customer relationship intangible assets, and debt issuance costs. In-place lease and customer relationship intangible assets are amortized on a straight-line basis over the applicable lives of the assets. Debt issuance costs are amortized over the term of the debt instrument on the effective interest method or the straight-line method when the effective interest method is not applicable. Goodwill is not amortized but is evaluated annually as of December 31 for impairment. Both the 2019 and 2018 impairment evaluations indicated that no impairment had occurred with respect to the $3.5 million
Contingent Liabilities	Contingent Liabilities From time to time, the Company may be subject to loss contingencies arising from legal proceedings and similar matters. Additionally, while the Company maintains comprehensive liability and property insurance with respect to each of its properties, the Company may be exposed to unforeseen losses related to uninsured or underinsured damages. The Company continually monitors any matters that may present a contingent liability, and, on a quarterly basis, management reviews the Company’s reserves and accruals in relation to each of them, adjusting provisions as necessary in view of changes in available information. Liabilities for contingencies are first recorded when a loss is determined to be both probable and can be reasonably estimated. Changes in estimates regarding the exposure to a contingent loss are reflected as adjustments to the related liability in the periods when they occur. Because of uncertainties inherent in the estimation of contingent liabilities, it is possible that the Company’s provision for contingent losses could change materially in the near term. To the extent that any significant losses, in addition to amounts recognized, are at least reasonably possible, such amounts will be disclosed in the notes to the Consolidated Financial Statements.
Stock-based Compensation	-Based Compensation The Company has various employee and director share-based awards outstanding. These awards include non-vested common stock and options to purchase common stock granted to employees pursuant to the 2015 Stock Incentive Plan and its predecessor plans (the “2015 Incentive Plan”) and the 2000 Employee Stock Purchase Plan (the “Employee Stock Purchase Plan”). The Company recognizes share-based payments to employees and directors in the Consolidated Statements of Income on a straight-line basis over the requisite service period based on the fair value of the award on the measurement date. See Note 12 for details on the Company’s share-based awards.
Accumulated Other Comprehensive Income (Loss)	Accumulated Other Comprehensive Income (Loss)
Revenue from Contract with Customers (Topic 606)	The Company’s three major types of revenue that are accounted for under Topic 606 that are listed above are all accounted for as the performance obligation is satisfied. The performance obligations that are identified for each of these items are satisfied over time and the Company recognizes revenue monthly based on this principle. One of the Company’s owned real estate properties as of December 31, 2018 and 2017 respectively, was covered under property operating agreements between the Company and a sponsoring health system, which contractually obligate the sponsoring health system to provide to the Company a minimum return on the Company’s investment in the property in exchange for the right to be involved in the operating decisions of the property, including tenancy. The agreement expired February 28, 2019. If the minimum return was not achieved through normal operations of the property, the Company calculated and accrued to property lease guaranty revenue, each quarter, any shortfalls due from the sponsoring health systems under the terms of the property operating agreement. Management fee income for property management services provided to third parties are generally calculated, accrued and billed monthly based on a percentage of cash collections of tenant receivables for the month or a stated amount per square foot. Internal management fee income, where the Company manages its owned properties, is eliminated in consolidation. Rental Income Revenue from Contracts with Customers (Topic 606) The Company recognizes certain revenue under the core principle of Topic 606. This requires an entity to recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. Lease revenue is not within the scope of Topic 606. To achieve the core principle, the Company applies the five step model specified in the guidance. See the New Accounting Pronouncements section below for additional information.
Federal Income Taxes	Federal Income Taxes No provision has been made for federal income taxes. The Company intends at all times to qualify as a REIT under Sections 856 through 860 of the Internal Revenue Code. The Company must distribute at least 90% per annum of its real estate investment trust taxable income to its stockholders and meet other requirements to continue to qualify as a real estate investment trust. See Note 15 for further discussion. The Company classifies interest and penalties related to uncertain tax positions, if any, in the Consolidated Financial Statements as a component of general and administrative expenses. No such amounts were recognized during the three years ended December 31, 2019. Federal tax returns for the years 2016, 2017 , 2018 and 2019 are currently subject to examination by taxing authorities.
State Income Taxes	State Income Taxes
Sales and Use Taxes	Sales and Use Taxes The Company must pay sales and use taxes to certain state tax authorities based on rents collected from tenants in properties located in those states. The Company is generally reimbursed for these taxes by the tenant. The Company accounts for the payments to the taxing authority and subsequent reimbursement from the tenant on a net basis in revenues in the Company’s Consolidated Statements of Income.
Assets Held for Sale	Assets Held for Sale
Earning Per Share	Earnings per Share The Company uses the two-class method of computing net earnings per common share. Earnings per common share is calculated by considering share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents as participating securities. Undistributed earnings (excess net income over dividend payments) are allocated on a pro rata basis to common shareholders and restricted shareholders. Undistributed losses (dividends in excess of net income) do not get allocated to restricted stockholders as they do not have the contractual obligation to share in losses. The amount of undistributed losses that applies to the restricted stockholders is allocated to the common stockholders.
New Accounting Pronouncements	New Accounting Pronouncements Accounting Standards Update No. 2016-02, No. 2018-01 and No. 2018-11 In February 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-02, "Leases." In January 2018, the FASB issued ASU 2018-01, "Leases - Land Easement Practical Expedient for Transition to Topic 842," in July 2018, the FASB issued ASU 2018-10, "Codification Improvements to Topic 842, Leases" and ASU 2018-11, "Leases - Targeted Improvements," and in December 2018, the FASB issued ASU 2018-20, “Narrow-Scope Improvements for Lessors.” These accounting standard updates are collectively referred to as "Topic 842." Topic 842 provides several practical expedients that the Company elected. These are (a) the package of practical expedients offered that allows an entity not to reassess upon adoption (i) whether an expired or existing contract contains a lease, (ii) lease classification related to expired or existing lease arrangements, and (iii) whether costs incurred on expired or existing leases qualify as initial direct costs, (b) the lessor practical expedient not to separate certain non-lease components, such as common area maintenance, from the lease component if (i) the timing and pattern of transfer are the same for the non-lease component and associated lease component, and (ii) the lease component would be classified as an operating lease if accounted for separately and (c) the lessee practical expedient not to separate certain non-lease components from the associated lease component. For lessees, the new standard establishes a right-of-use ("ROU") model that requires a lessee to record a ROU asset and a lease liability on the balance sheet for all leases with terms longer than 12 months. Leases are classified as either finance or operating, with the classification affecting the pattern of expense recognition in the income statement. The Company's ground leases executed or assumed prior to the adoption of Topic 842 continue to be accounted for as operating leases and will not result in a materially different ground lease expense. However, each ground lease executed by the Company after the adoption of Topic 842 will be evaluated to determine if it is an operating or finance lease. If the lease is to be accounted for as a finance lease, ground lease expense would be accounted for using the effective interest method instead of the straight-line method over the term of the lease, which would result in higher ground lease expense in the earlier years of a ground lease when compared to the straight-line method. Leases in which the Company is the lessee are primarily ground leases, but also includes management office leases in third party buildings and certain copier and postage machine leases. The terms of the ground leases generally range from 40 to 99 years with a weighted average remaining lease term remaining of 52.1 years, excluding renewal options. The Company's discount rates, which approximates the Company's incremental borrowing rate, ranged from 3.8% for leases expiring in 2021 to 6.2% for leases expiring in 2115. The Company utilized a third party to assist in determining the discount rates for its ground leases. The discount rates consider the general economic environment and factor in various financing and asset specific adjustments so that the discount rate is appropriate for the intended use of the underlying lease. As of January 1, 2019, the Company recognized the present value of its lease payments and a corresponding lease liability of $91.7 million . In addition, the Company reclassified $45.0 million of prepaid ground leases and below-market lease intangibles from the Other assets line item, $1.9 million of above-market lease intangibles from the Other liabilities line and $8.4 million of straight-line rent from the Accounts payable and accrued liabilities line item to the Operating lease right-of-use assets line item on the Consolidated Balance Sheet. For lessors, the new standard requires a lessor to classify leases as either sales-type, direct-financing or operating. A lease will be treated as a sale if it is considered to transfer control of the underlying asset to the lessee. A lease will be classified as direct-financing if risks and rewards are conveyed without the transfer of control. Otherwise, the lease is treated as an operating lease. Lessor accounting remains largely unchanged with some exceptions including the concept of separating lease and nonlease components. Nonlease components, such as common area maintenance, are generally accounted for under Topic 606 and separated from the lease payments. However, the Company elected the lessor practical expedient allowing the Company to not separate these components when certain conditions are met. The combined component is accounted for under Topic 842. The adoption of Topic 842, where the Company is the lessor, did not have a material impact on the Company's Consolidated Financial Statements for the twelve months ended months ended December 31, 2019 . The new standard was effective for the Company on January 1, 2019. Topic 842 provides two transition alternatives. The Company elected the prospective optional transition method available to apply Topic 842 in the year of adoption and the guidance in Accounting Standards Codification Topic 840 in the comparative periods. Topic 842 includes extensive quantitative and qualitative disclosures as compared to Topic 840, Leases, for both lessees and lessors. See Note 3 to the Company's Consolidated Financial Statements for additional disclosures. Accounting Standards Update No. 2016-13 In June 2016, the FASB issued ASU 2016-13, "Measurement of Credit Losses on Financial Instruments." This update is intended to improve financial reporting by requiring timelier recognition of credit losses on loans and other financial instruments that are not accounted for at fair value through net income, including loans held for investment, held-to-maturity debt securities, trade and other receivables, net investment in leases and other such commitments. This update requires that financial statement assets measured at an amortized cost and certain other financial instruments be presented at the net amount expected to be collected, through an allowance for credit losses that is deducted from the amortized cost basis. This standard is effective for annual and interim periods beginning after December 15, 2019 with early adoption permitted. Operating lease receivables, representing the majority of the Company's receivables, are not within the scope of the new standard. The Company adopted this standard as of January 1, 2020. There was a not material impact to the Consolidated Financial Statements from the adoption of this standard. Accounting Standards Update No. 2017-04 In January 2017, the FASB issued ASU 2017-04, "Simplifying the Test for Goodwill Impairment." This update eliminates Step 2 of the goodwill impairment test. As such, an entity will perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount. An entity should recognize a goodwill impairment charge for the amount by which the reporting unit's carrying amount exceeds its fair value. This standard is effective for the Company for annual and interim periods beginning after December 15, 2019. The Company adopted this standard as of January 1, 2020. There was not a material impact to the Consolidated Financial Statements from the adoption of this standard.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2019
Accounting Policies [Abstract]
Schedule of assets' estimated useful life	Depreciation and amortization of real estate assets and liabilities in place as of December 31, 2019 , is provided for on a straight-line basis over the asset’s estimated useful life: Land improvements 3.0 to 39.0 years Buildings and improvements 3.3 to 39.0 years Lease intangibles (including ground lease intangibles) 2.1 to 99.0 years Personal property 2.8 to 20.0 years
Schedule of disaggregation of revenue	Below is a detail of the amounts by category: YEAR ENDED DECEMBER 31, In thousands 2019 2018 2017 Type of Revenue Parking income $ 7,520 $ 6,930 $ 6,611 Property lease guaranty income 128 675 726 Management fee income 270 273 308 Miscellaneous 155 114 114 $ 8,073 $ 7,992 $ 7,759
Schedule of rental income	The components of rental income are as follows: YEAR ENDED DECEMBER 31, (Dollars in thousands) 2019 2018 2017 Property operating income $ 415,142 $ 390,256 $ 358,009 Single-tenant net lease 44,083 47,860 52,897 Straight-line rent 3,000 4,281 6,072 Rental income $ 462,225 $ 442,397 $ 416,978

Property Investments (Tables)

Property Investments (Tables)	12 Months Ended
	Dec. 31, 2019
Real Estate Investment Property, Net [Abstract]
Schedule of property investment	The following table summarizes the Company’s investments at December 31, 2019. Dollars in thousands NUMBER OF PROPERTIES LAND BUILDINGS, IMPROVEMENTS, AND LEASE INTANGIBLES PERSONAL PROPERTY TOTAL ACCUMULATED DEPRECIATION Seattle, WA 25 $ 58,565 $ 532,767 $ 421 $ 591,753 $ (88,890 ) Dallas, TX 25 19,194 496,683 442 516,319 (181,556 ) Los Angeles, CA 14 44,386 205,829 347 250,562 (95,979 ) Atlanta, GA 9 3,679 212,509 84 216,272 (20,040 ) Nashville, TN 6 20,053 180,463 1,109 201,625 (64,038 ) Charlotte, NC 16 4,200 176,261 105 180,566 (67,040 ) Denver, CO 9 16,514 134,004 271 150,789 (25,265 ) Washington, D.C. 6 — 150,304 21 150,325 (25,097 ) Richmond, VA 7 — 149,132 106 149,238 (44,204 ) Houston, TX 9 16,211 132,013 78 148,302 (44,229 ) Honolulu, HI 3 8,327 135,641 159 144,127 (39,165 ) Des Moines, IA 7 12,665 126,401 99 139,165 (34,725 ) Oklahoma City, OK 4 10,401 115,706 15 126,122 (19,351 ) Indianapolis, IN 4 3,299 118,847 — 122,146 (26,082 ) San Francisco, CA 3 14,054 107,396 43 121,493 (20,906 ) Springfield, MO 1 1,989 109,304 — 111,293 (17,740 ) Austin, TX 5 14,236 92,809 123 107,168 (24,048 ) Memphis, TN 7 5,241 92,508 194 97,943 (37,582 ) San Antonio, TX 6 6,487 88,583 404 95,474 (40,573 ) Chicago, IL 3 5,859 87,588 211 93,658 (23,540 ) Minneapolis, MN 4 2,090 62,359 — 64,449 (10,486 ) Other (16 markets) 31 17,079 475,409 806 493,294 (165,159 ) 204 284,529 3,982,516 5,038 4,272,083 (1,115,695 ) Construction in progress — — 48,731 — 48,731 — Land held for development — 24,647 — — 24,647 (671 ) Memphis Redevelopment — 5,222 3,810 — 9,032 (50 ) Corporate property — — — 5,500 5,500 (4,686 ) Total real estate investments 204 $ 314,398 $ 4,035,057 $ 10,538 $ 4,359,993 $ (1,121,102 )

Leases (Tables)

Leases (Tables)	12 Months Ended
	Dec. 31, 2019
Leases [Abstract]
Schedule of future minimum lease payments due to the Company under property operating agreements	Future minimum lease payments under the non-cancelable operating leases, excluding any reimbursements, as of December 31, 2019 are as follows: In thousands 2020 $ 360,340 2021 315,426 2022 275,798 2023 233,424 2024 177,738 2025 and thereafter 501,849 $ 1,864,575
Future minimum lease payments receivable under ASC 840	Future minimum lease payments under the non-cancelable operating leases, excluding any reimbursements, as of December 31, 2018 were as follows: In thousands 2019 $ 326,441 2020 279,211 2021 235,660 2022 201,072 2023 163,978 2024 and thereafter 476,673 $ 1,683,035
Schedule of future minimum operating lease payments	The Company’s future lease payments (primarily for its 62 non-prepaid ground leases) as of December 31, 2019 were as follows: In thousands OPERATING FINANCING 2020 $ 4,814 $ 746 2021 4,844 754 2022 4,875 763 2023 4,913 774 2024 4,969 795 2025 and thereafter 307,665 83,404 Total undiscounted lease payments 332,080 87,236 Discount (240,506 ) (69,199 ) Lease liabilities $ 91,574 $ 18,037
Future minimum lease payments under ASC 840	The Company’s future minimum lease payments (primarily for its 60 non-prepaid ground leases) as of December 31, 2018 were as follows: In thousands 2019 $ 5,288 2020 5,260 2021 5,238 2022 5,207 2023 5,224 2024 and thereafter 323,533 $ 349,750
Schedule of future minimum finance lease payments	The Company’s future lease payments (primarily for its 62 non-prepaid ground leases) as of December 31, 2019 were as follows: In thousands OPERATING FINANCING 2020 $ 4,814 $ 746 2021 4,844 754 2022 4,875 763 2023 4,913 774 2024 4,969 795 2025 and thereafter 307,665 83,404 Total undiscounted lease payments 332,080 87,236 Discount (240,506 ) (69,199 ) Lease liabilities $ 91,574 $ 18,037
Schedule of lease cost	The following table provides details of the Company's total lease expense for the year ended December 31, 2019 : In thousands YEAR ENDED Dec. 31, 2019 Operating lease cost Operating lease expense $ 4,623 Variable lease expense 3,161 Finance lease cost Amortization of right-of-use assets 165 Interest on lease liabilities 616 Total lease expense $ 8,565 Other information Operating cash flows outflows related to operating leases $ 6,972 Financing cash flows outflows related to financing leases $ 379 Right-of-use assets obtained in exchange for new finance lease liabilities $ 17,800 Weighted-average remaining lease term (excluding renewal options) - operating leases 49.5 Weighted-average remaining lease term (excluding renewal options) -finance leases 65.2 Weighted-average discount rate - operating leases 5.7 % Weighted-average discount rate - finance leases 5.4 %

Acquisitions, Dispositions an_2

Acquisitions, Dispositions and Mortgage Repayments (Tables)	12 Months Ended
	Dec. 31, 2019
Acquisitions and Dispositions and Mortgage Repayments [Abstract]
Schedule of acquisitions	The following table details the Company's acquisitions for the year ended December 31, 2018: Dollars in millions TYPE 1 DATE ACQUIRED PURCHASE PRICE MORTGAGE NOTES PAYABLE ASSUMED 2 CASH 3 REAL ESTATE OTHER 4 SQUARE FOOTAGE Seattle, WA MOB 5/4/18 $ 7.8 $ — $ 7.8 $ 7.8 $ — 13,314 Denver, CO 5 MOB 5/18/18 12.1 (8.0 ) 3.8 12.1 (0.2 ) 93,992 Denver, CO 5 OFC 5/18/18 12.9 — 12.8 13.0 (0.2 ) 93,869 Oklahoma City, OK MOB 5/21/18 11.4 — 11.4 11.5 (0.1 ) 82,647 Seattle, WA MOB 6/29/18 26.2 — 26.2 26.7 (0.5 ) 86,942 Denver, CO MOB 8/24/18 4.1 — 4.2 4.2 — 17,084 Nashville, TN OFC 12/4/18 31.9 — 32.0 32.0 — 108,691 Chicago, IL 6 MOB 12/19/18 5.1 — 4.9 5.1 (0.2 ) 14,883 $ 111.5 $ (8.0 ) $ 103.1 $ 112.4 $ (1.2 ) 511,422 1 MOB = medical office building; OFC = office 2 The mortgage note payable assumed in the acquisition does not reflect the fair value premium totaling $0.1 million recorded by the Company upon acquisition (included in Other). 3 Cash consideration excludes prorations of revenue and expense due to/from seller at the time of the acquisition. 4 Includes other assets acquired, liabilities assumed, intangibles recognized at acquisition and fair value adjustments on debt assumed. 5 The mortgage note payable assumed at acquisition encumbers both buildings. 6 The Company acquired an additional suite in a previously acquired medical office building. The following table details the Company's acquisitions for the year ended December 31, 2019 : Dollars in millions TYPE 1 DATE ACQUIRED PURCHASE PRICE CASH 2 REAL ESTATE OTHER 3 SQUARE FOOTAGE Washington, D.C. 4 MOB 3/28/19 $ 46.0 $ 45.9 $ 50.2 $ (4.3 ) 158,338 Indianapolis, IN 5 MOB 3/28/19 47.0 44.8 43.7 1.1 143,499 Atlanta, GA MOB 4/2/19 28.0 28.0 28.0 — 47,963 Dallas, TX MOB 6/10/19 17.0 16.7 17.0 (0.3 ) 89,990 Seattle, WA MOB 6/11/19 7.7 7.8 7.8 — 29,870 Seattle, WA MOB 6/14/19 19.0 19.1 19.5 (0.4 ) 47,255 Seattle, WA MOB 6/28/19 30.5 30.4 30.6 (0.2 ) 78,288 Houston, TX MOB 8/1/19 13.5 13.5 13.5 — 29,903 Oklahoma City, OK MOB 9/26/19 4.1 4.1 4.1 — 28,542 Los Angeles, CA 6 MOB 9/30/19 61.1 60.9 61.8 (0.9 ) 115,634 Raleigh, NC MOB 10/31/19 21.6 22.0 21.7 0.3 57,730 Dallas, TX 7 MOB 10/31/19 20.1 19.5 20.2 (0.7 ) 48,192 Seattle, WA MOB 11/18/19 22.8 23.1 23.2 (0.1 ) 36,350 Seattle, WA MOB 12/10/19 24.2 24.5 24.6 (0.1 ) 44,166 Memphis, TN MOB 12/13/19 8.7 8.9 8.9 — 110,883 Seattle, WA MOB 12/18/19 10.0 9.3 9.9 (0.6 ) 20,109 $ 381.3 $ 378.5 $ 384.7 $ (6.2 ) 1,086,712 1 MOB = medical office building. 2 Cash consideration excludes prorations of revenue and expense due to/from seller at the time of the acquisition. 3 Includes other assets acquired, liabilities assumed, and intangibles recognized at acquisition. 4 Includes two properties. The Company assumed two ground leases in connection with this acquisition that are classified as financing leases. The present value of future lease payments totaling $14.3 million was recorded on the Company's Consolidated Balance Sheets under the caption Finance lease liabilities. In addition, the right-of-use assets were partially offset by $5.2 million of above-market lease intangibles included in Other. 5 The Company assumed a prepaid ground lease totaling $0.8 million and recorded a below-market lease intangible totaling $0.9 million in connection with this acquisition that is classified as an operating lease that is included in Other. 6 Includes two properties. 7 The Company assumed a ground lease in connection with this acquisition that is classified as a financing lease. The present value of future lease payments totaling $3.6 million was recorded on the Company's Consolidated Balance Sheets under the caption Finance lease liabilities.
Schedule of assets acquired and liabilities assumed	The following table summarizes the estimated relative fair values of the assets acquired and liabilities assumed in the real estate acquisitions for 2019 as of the acquisition date: ESTIMATED FAIR VALUE in millions ESTIMATED USEFUL LIFE in years Building $ 270.7 8.0 - 37.0 Land 59.1 — Land Improvements 4.2 3.0 - 12.0 Intangibles At-market lease intangibles 50.7 3.3 - 9.2 Above-market lease intangibles (lessor) 0.7 2.4 - 9.9 Below-market lease intangibles (lessor) (0.7 ) 1.2 - 8.6 Above-market lease intangibles (lessee) (5.1 ) 69.1 - 72.3 Below-market lease intangibles (lessee) 0.9 65.1 Other assets acquired 2.3 Accounts payable, accrued liabilities and other liabilities assumed (4.3 ) Total cash paid $ 378.5 The following table summarizes the estimated relative fair values of the assets acquired and liabilities assumed in the real estate acquisitions for 2018 as of the acquisition date: ESTIMATED FAIR VALUE in millions ESTIMATED USEFUL LIFE in years Building $ 64.0 20.0 - 30.0 Land 31.4 — Land Improvements 2.7 5.0 - 13.5 Intangibles At-market lease intangibles (lessor) 14.3 1.3 - 4.2 Below-market lease intangibles (lessor) (0.1 ) 3.8 Mortgage notes payable assumed, including fair value adjustments (8.0 ) Other assets acquired 0.2 Accounts payable, accrued liabilities and other liabilities assumed (1.4 ) Total cash paid $ 103.1
Schedule of dispositions	The following table details the Company's dispositions for the year ended December 31, 2019 : Dollars in millions TYPE 1 DATE DISPOSED SALES PRICE CLOSING ADJUSTMENTS NET PROCEEDS NET REAL ESTATE INVESTMENT OTHER 2 GAIN/ SQUARE FOOTAGE Tucson, AZ 3 MOB 4/9/19 $ 13.0 $ (0.9 ) $ 12.1 $ 6.9 $ 0.4 $ 4.8 67,345 Virginia Beach, VA 4 MOB 8/1/19 1.3 (0.1 ) 1.2 1.2 — — 10,000 San Antonio, TX MOB 8/28/19 0.9 (0.1 ) 0.8 0.6 — 0.2 10,138 Erie, PA IRF 10/25/19 14.0 — 14.0 1.3 — 12.7 90,123 New Orleans, LA 5 MOB 11/25/19 3.7 (0.2 ) 3.5 1.2 0.2 2.1 136,155 Kingsport, TN SNF 11/27/19 9.5 (0.3 ) 9.2 5.0 1.3 2.9 75,000 Pittsburgh, PA 6 IRF 12/18/19 3.8 (0.3 ) 3.5 3.5 — — 78,731 Dallas, TX 5 MOB 12/30/19 8.7 (0.6 ) 8.1 6.1 (0.4 ) 2.4 69,558 $ 54.9 $ (2.5 ) $ 52.4 $ 25.8 $ 1.5 $ 25.1 537,050 1 MOB = medical office building; IRF = inpatient rehabilitation facility; SNF = skilled nursing facility 2 Includes straight-line rent receivables, leasing commissions and lease inducements. 3 Includes four properties sold to a single purchaser. 4 The Company reclassified this property to held for sale during the second quarter of 2019 and recorded an impairment charge of $0.4 million based on the sales price less estimated costs to sell. 5 Includes two properties. 6 The Company reclassified this property to held for sale during the first quarter of 2017 and subsequently in the second quarter of 2019, the Company accepted an offer to purchase and recorded an impairment charge of $5.2 million . 2018 Real Estate Asset Dispositions The following table details the Company's dispositions for the year ended December 31, 2018: Dollars in millions TYPE 1 DATE DISPOSED SALES PRICE CLOSING ADJUSTMENTS NET PROCEEDS NET REAL ESTATE INVESTMENT OTHER 3 GAIN/ SQUARE FOOTAGE Roanoke, VA 2, 4 MOB, OFC 4/26/18 $ 46.2 $ — $ 46.2 $ 23.9 $ — $ 22.3 460,881 Michigan 5 SNF 6/27/18 9.5 (0.7 ) 8.8 3.4 — 5.4 121,672 St. Louis, MO MOB 8/30/18 9.8 (0.5 ) 9.3 7.5 0.5 1.3 70,893 Denver, CO IRF 12/20/18 16.9 (0.3 ) 16.6 9.2 1.4 6.0 34,068 Cleveland, TN MOB 12/21/18 13.3 (0.2 ) 13.1 8.6 0.4 4.1 81,382 Tucson, AZ MOB 12/27/18 3.0 (0.2 ) 2.8 1.9 0.2 0.7 37,310 $ 98.7 $ (1.9 ) $ 96.8 $ 54.5 $ 2.5 $ 39.8 806,206 1 MOB = medical office building; IRF = inpatient rehabilitation facility; OFC = office; SNF = skilled nursing facility 2 Previously classified as held for sale. 3 Includes straight-line rent receivables, leasing commissions and lease inducements. 4 Includes seven properties and comprised of five single-tenant net lease buildings and two multi-tenant buildings. These buildings were sold pursuant to the exercise of a fixed-price purchase option. 5 Includes five skilled nursing facilities. Sales price includes $0.5 million of forfeited earnest money from a prior terminated transaction.

Held for Sale (Tables)

Held for Sale (Tables)	12 Months Ended
	Dec. 31, 2019
Discontinued Operations and Disposal Groups [Abstract]
Schedule of disposal groups, including discontinued operations, income statement, balance sheet and additional disclosures	The table below reflects the assets and liabilities of the properties classified as held for sale as of December 31, 2019 and 2018 . DECEMBER 31, Dollars in thousands 2019 2018 Balance Sheet data Land $ — $ 1,125 Buildings, improvements and lease intangibles — 18,231 — 19,356 Accumulated depreciation — (10,657 ) Real estate assets held for sale, net — 8,699 Other assets, net 37 573 Assets held for sale, net $ 37 $ 9,272 Accounts payable and accrued liabilities $ 37 $ 450 Other liabilities 108 137 Liabilities of properties held for sale $ 145 $ 587

Other Assets (Tables)

Other Assets (Tables)	12 Months Ended
	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of items included in other assets	Items included in "Other assets, net" on the Company’s Consolidated Balance Sheets as of December 31, 2019 and 2018 are detailed in the table below: DECEMBER 31, Dollars in millions 2019 2018 Straight-line rent receivables $ 70.5 $ 69.5 Prepaid assets 44.3 66.2 Additional long-lived assets, net 22.7 23.5 Accounts receivable, net 13.0 9.7 Ground lease modification, net 9.4 9.9 Equity investments in joint ventures 8.1 8.5 Debt issuance costs, net 1 5.0 2.2 Project costs 4.6 2.2 Goodwill 3.5 3.5 Customer relationship intangible assets, net 2.5 1.7 Above-market intangible assets, net 2 1.2 16.8 Interest rate swap assets — 0.2 Other 0.6 0.8 $ 185.4 $ 214.7 1 Includes debt issuance costs related to the Company's Unsecured Credit Facility and Unsecured Term Loan due 2026. 2 Includes below-market ground lease intangibles as of December 31, 2018. These intangibles were reclassified to Operating right-of-use assets on the Company's Consolidated Balance Sheets as of December 31, 2019.
Schedule of equity method investments	The Company's investment in and income (loss) recognized for the years ended December 31, 2019 and 2018 related to its LLCs accounted for under the equity method are shown in the table below: DECEMBER 31, Dollars in millions 2019 2018 Net LLC investments, beginning of period $ 8.5 $ 8.7 Equity income (loss) recognized during the period — — Owner distributions (0.4 ) (0.2 ) Net LLC investments, end of period $ 8.1 $ 8.5

Intangible Assets and Liabili_2

Intangible Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of finite lived intangible assets and liabilities	The Company’s intangible assets and liabilities as of December 31, 2019 and 2018 consisted of the following: GROSS BALANCE at December 31, ACCUMULATED AMORTIZATION at December 31, WEIGHTED AVG. REMAINING LIFE in years BALANCE SHEET CLASSIFICATION Dollars in millions 2019 2018 2019 2018 Goodwill $ 3.5 $ 3.5 $ — $ — N/A Other assets, net Credit facility debt issuance costs 5.8 5.4 0.8 3.2 3.8 Other assets, net Above-market lease intangibles (lessor) 4.0 4.5 2.8 3.3 3.9 Other assets, net Customer relationship intangibles (lessor) 4.1 2.7 1.6 1.0 43.1 Other assets, net Below-market lease intangibles (7.3 ) (7.3 ) (4.0 ) (4.0 ) 6.7 Other liabilities Debt issuance costs 1 9.2 9.3 3.5 2.8 5.8 Notes and bonds payable At-market lease intangibles 147.9 114.4 59.8 52.0 5.4 Real estate properties Above-market lease intangibles (lessee) (7.2 ) (2.0 ) (0.2 ) (0.1 ) 75.5 Right-of-use asset Below-market lease intangibles (lessee) 18.8 17.8 2.5 2.2 63.0 Right-of-use asset $ 178.8 $ 148.3 $ 66.8 $ 60.4 16.6 1 Includes debt issuance costs related to the Company's Unsecured Senior Notes payable, Unsecured Term Loan due 2024, and mortgage notes payable.
Schedule of expected net future amortization expense	The following table represents expected amortization over the next five years of the Company’s intangible assets and liabilities in place as of December 31, 2019 : Dollars in millions FUTURE AMORTIZATION OF INTANGIBLES, NET 2019 $ 24.1 2020 19.1 2021 16.0 2022 11.2 2023 7.0

Notes and Bonds Payable (Tables

Notes and Bonds Payable (Tables)	12 Months Ended
	Dec. 31, 2019
Debt Instrument [Line Items]
Schedule of debt	DECEMBER 31, MATURITY DATES CONTRACTUAL INTEREST RATES PRINCIPAL PAYMENTS INTEREST PAYMENTS Dollars in thousands 2019 2018 Unsecured Credit Facility $ 293,000 $ 262,000 5/23 LIBOR + .90% At maturity Monthly Unsecured Term Loan due 2024 1 199,013 149,183 5/24 LIBOR + 1.00% At maturity Monthly Unsecured Term Loan due 2026 2 — — 6/26 LIBOR + 1.60% At maturity Monthly Senior Notes due 2023 1 248,540 248,117 4/23 3.75 % At maturity Semi-Annual Senior Notes due 2025 1 248,522 248,278 5/25 3.88 % At maturity Semi-Annual Senior Notes due 2028 1 295,651 295,198 1/28 3.63 % At maturity Semi-Annual Mortgage notes payable 3 129,343 143,208 7/20-5/40 3.31%-6.88% Monthly Monthly $ 1,414,069 $ 1,345,984 1 Balances are shown net of discounts and unamortized issuance costs. 2 As of December 31, 2019, there are no outstanding loans under the Unsecured Term Loan 2026. This term loan has a delayed draw feature that allows the Company up to February 2020 to draw against the $150 million commitments. 3 Balances are shown net of discounts and unamortized issuance costs and include premiums.
Schedule of mortgage notes payable	The following table details the Company’s mortgage notes payable, with related collateral. ORIGINAL BALANCE EFFECTIVE INTEREST RATE 20 MATURITY DATE COLLATERAL 21 PRINCIPAL AND INTEREST PAYMENTS 19 INVESTMENT IN COLLATERAL at December 31, BALANCE at December 31, Dollars in millions 2019 2019 2018 Commercial Bank 1 $ 9.4 4.55 % 7/19 MOB Monthly/8-yr amort $ — $ — $ 9.0 Commercial Bank 2 15.2 7.65 % 7/20 MOB 18 18.6 12.5 12.5 Life Insurance Co. 3 7.9 4.00 % 8/20 MOB Monthly/15-yr amort. 20.7 0.5 1.3 Life Insurance Co. 4 7.3 5.25 % 8/20 MOB Monthly/27-yr amort. 18.1 6.0 6.2 Life Insurance Co. 5 5.6 4.30 % 1/21 MOB Monthly/10-yr amort. 15.8 4.5 4.6 Commercial Bank 6 12.9 6.43 % 2/21 MOB Monthly/12-yr amort. 55.2 10.1 10.3 Life Insurance Co. 7 11.0 3.87 % 11/22 MOB Monthly/7-yr amort. 22.0 10.0 10.2 Life Insurance Co. 8 12.3 3.86 % 8/23 MOB Monthly/7-yr amort. 25.4 10.9 11.2 Financial Services 9 12.4 4.27 % 10/23 MOB Monthly/10-yr amort. 22.6 11.7 12.0 Life Insurance Co. 10 9.0 4.84 % 12/23 MOB,OFC Monthly/10-yr amort. 25.7 7.6 7.8 Life Insurance Co. 11 13.3 4.13 % 1/24 MOB Monthly/10-yr amort. 20.8 12.7 13.0 Life Insurance Co. 12 6.8 3.96 % 2/24 MOB Monthly/7-yr amort. 14.6 6.4 6.6 Financial Services 13 9.7 4.32 % 9/24 MOB Monthly/10-yr amort. 17.0 8.3 8.6 Commercial Bank 11.5 3.71 % 1/26 MOB Monthly/10-yr amort. 38.6 9.6 10.1 Commercial Bank 14 15.0 5.25 % 4/27 MOB Monthly/20-yr amort. 33.5 7.9 8.8 Municipal Government 15, 16 11.0 4.79 % 17 MOB Semi-Annual 17 21.0 10.6 11.0 $ 369.6 $ 129.3 $ 143.2 1 The Company repaid this mortgage note in April 2019. The Company's unencumbered gross investment was $27.8 million at December 31, 2019. 2 The unaccreted portion of the $2.4 million discount recorded on this note upon acquisition is included in the balance above. 3 The unamortized portion of the $0.3 million premium recorded on this note upon acquisition is included in the balance above. 4 The unamortized portion of the $0.4 million premium recorded on this note upon acquisition is included in the balance above. This mortgage note payable was repaid in full on February 3, 2020. 5 The unamortized portion of the $0.2 million premium recorded on this note upon acquisition is included in the balance above. 6 The unaccreted portion of the $1.0 million discount recorded on this note upon acquisition is included in the balance above. 7 The unaccreted portion of the $0.1 million discount recorded on this note upon acquisition is included in the balance above. 8 The unaccreted portion of the $0.2 million discount recorded on this note upon acquisition is included in the balance above. 9 The unamortized portion of the $0.4 million premium recorded on this note upon acquisition is included in the balance above. 10 The unamortized portion of the $0.1 million premium recorded on this note upon acquisition is included in the balance above. 11 The unamortized portion of the $0.8 million premium recorded on this note upon acquisition is included in the balance above. 12 The unamortized portion of the $0.2 million premium recorded on this note upon acquisition is included in the balance above. 13 The unamortized portion of the $0.1 million premium recorded on this note upon acquisition is included in the balance above. 14 The unamortized portion of the $0.7 million premium recorded on this note upon acquisition is included in the balance above. 15 Balance consists of three notes secured by the same building. 16 The unamortized portion of the $1.0 million premium recorded on the three notes upon acquisition is included in the balance above. 17 These three mortgage notes payable are series municipal bonds that have maturity dates ranging from from May 2022 to May 2040. One of the four original notes payable was repaid upon maturity in May 2017. The remaining three require interest only payments and have future maturity dates but allow repayment after May 2020 without penalty. The Company intends on repaying all three notes payable at that time. 18 Payable in monthly installments of interest only for 24 months and then installments of principal and interest based on an 11 -year amortization with the final payment due at maturity. 19 Payable in monthly installments of principal and interest with the final payment due at maturity (unless otherwise noted). 20 The contractual interest rates for the 17 outstanding mortgage notes ranged from 3.3% to 6.9% as of December 31, 2019 . 21 MOB-Medical office building. OFC-Office
Schedule of future contractual maturities of the company's notes and bonds payable	Future maturities of the Company’s notes and bonds payable as of December 31, 2019 were as follows: Dollars in thousands PRINCIPAL MATURITIES NET ACCRETION/ AMORTIZATION 1 DEBT ISSUANCE COSTS 2 NOTES AND BONDS PAYABLE % 2020 $ 23,064 $ (392 ) $ (1,081 ) $ 21,591 1.5 % 2021 17,594 (326 ) (1,065 ) 16,203 1.1 % 2022 12,977 (336 ) (1,077 ) 11,564 0.8 % 2023 573,230 (183 ) (921 ) 572,126 40.5 % 2024 225,966 (262 ) (667 ) 225,037 15.9 % 2025 and thereafter 569,427 (849 ) (1,030 ) 567,548 40.2 % $ 1,422,258 $ (2,348 ) $ (5,841 ) $ 1,414,069 100.0 % 1 Includes discount accretion and premium amortization related to the Company’s Senior Notes due 2023, Senior Notes due 2025, Senior Notes due 2028 and 16 mortgage notes payable. 2 Excludes approximately $5.0 million in debt issuance costs related to the Company's Unsecured Credit Facility and Unsecured Term Loan due 2026 included in other assets, net.
Medium-term Notes [Member] | Term Loan due 2024 [Member]
Debt Instrument [Line Items]
Schedule of debt	The following table reconciles the balance of the Unsecured Term Loan due 2024 on the Company’s Consolidated Balance Sheets as of December 31, 2019 and 2018 : DECEMBER 31, Dollars in thousands 2019 2018 Unsecured Term Loan due 2024 principal balance $ 200,000 $ 150,000 Debt issuance costs (987 ) (817 ) Unsecured Term Loan due 2024 carrying amount $ 199,013 $ 149,183
Senior Notes [Member] | Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Schedule of debt	The following table reconciles the balance of the Senior Notes due 2023 on the Company’s Consolidated Balance Sheets as of December 31, 2019 and 2018 : DECEMBER 31, Dollars in thousands 2019 2018 Senior Notes due 2023 face value $ 250,000 $ 250,000 Unaccreted discount (761 ) (974 ) Debt issuance costs (699 ) (909 ) Senior Notes due 2023 carrying amount $ 248,540 $ 248,117
Senior Notes [Member] | Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Schedule of debt	The following table reconciles the balance of the Senior Notes due 2025 on the Company’s Consolidated Balance Sheets as of December 31, 2019 and 2018 : DECEMBER 31, Dollars in thousands 2019 2018 Senior Notes due 2025 face value $ 250,000 $ 250,000 Unaccreted discount (121 ) (141 ) Debt issuance costs (1,357 ) (1,581 ) Senior Notes due 2028 carrying amount $ 248,522 $ 248,278
Senior Notes [Member] | Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Schedule of debt	The following table reconciles the balance of the Senior Notes due 2028 on the Company’s Consolidated Balance Sheets as of December 31, 2019 : DECEMBER 31, Dollars in thousands 2019 2018 Senior Notes due 2028 face value $ 300,000 $ 300,000 Unaccreted discount (2,100 ) (2,319 ) Debt issuance costs (2,249 ) (2,483 ) Senior Notes due 2028 carrying amount $ 295,651 $ 295,198
Mortgage Notes [Member] | Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Schedule of debt	The following table reconciles the Company’s aggregate mortgage notes principal balance with the Company’s Consolidated Balance Sheets as of December 31, 2019 and 2018 . For the years ended December 31, 2019 , 2018 and 2017 , the Company amortized approximately $0.6 million, $0.4 million and $0.3 million of the discount and $0.4 million, $0.8 million, and $0.7 million of the premium. For the years ended December 31, 2019 , 2018 and 2017 , the Company also amortized approximately $0.2 million, $0.1 million , and $0.1 million of the debt issuance costs, respectively, on the mortgage notes payable which is included in interest expense on the Company’s Consolidated Statements of Income. DECEMBER 31, Dollars in thousands 2019 2018 Mortgage notes payable principal balance $ 129,258 $ 143,115 Unamortized premium 1,162 1,805 Unaccreted discount (528 ) (968 ) Debt issuance costs (549 ) (744 ) Mortgage notes payable carrying amount $ 129,343 $ 143,208

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of cash flow hedges included in accumulated other comprehensive income (loss)	The table below presents the effect of cash flow hedge accounting on Accumulated other comprehensive income (loss) as of December 31, 2019 related to the Company's outstanding interest rate swaps. AMOUNT OF (LOSS) RECOGNIZED IN OCI on derivatives AMOUNT OF (GAIN)/LOSS RECLASSIFIED FROM OCI INTO INCOME for the twelve months ended December 31, Dollars in thousands 2019 2019 2018 Interest rate swaps 2017 $ (674 ) Interest expense $ (22 ) $ 51 Interest rate swaps 2018 (1,366 ) Interest expense 99 204 Interest rate swaps 2019 (3,552 ) Interest expense 74 — Settled interest rate swaps — Interest expense 168 169 $ (5,592 ) Total interest expense $ 319 $ 424 INTEREST RATE DERIVATIVE NUMBER OF INSTRUMENTS NOTIONAL in millions Interest rate swaps - 2017 2 $ 25.0 Interest rate swaps - 2018 2 50.0 Interest rate swaps - 2019 4 100.0 Total interest rate swaps 8 $ 175.0
Schedule of derivative instruments in statement of financial position, fair value	The table below presents the fair value of the Company's derivative financial instruments, as well as, their classification on the Consolidated Balance Sheets as of December 31, 2019 and 2018 . AS OF DECEMBER 31, 2019 AS OF DECEMBER 31, 2018 Dollars in thousands BALANCE SHEET LOCATION FAIR VALUE BALANCE SHEET LOCATION FAIR VALUE Derivatives designated as hedging instruments Interest rate swaps 2017 Other liabilities $ (467 ) Other assets, net $ 229 Interest rate swaps 2018 Other liabilities (1,335 ) Other liabilities (68 ) Interest rate swaps 2019 Other liabilities (3,478 ) Other liabilities — Total derivatives designated as hedging instruments $ (5,280 ) $ 161
Schedule of offsetting assets	The table below presents a gross presentation, the effects of offsetting, and a net presentation of the Company's derivatives as of December 31, 2019. The net amounts of derivative liabilities can be reconciled to the tabular disclosure of fair value. The tabular disclosure of fair value provides the location that derivative liabilities are presented on the Company's Consolidated Balance Sheets. Offsetting of Derivative Liabilities GROSS AMOUNTS of recognized liabilities GROSS AMOUNTS OFFSET in the Consolidated Balance Sheets NET AMOUNTS OF LIABILITIES presented in the Consolidated Balance Sheets GROSS AMOUNTS NOT OFFSET in the Consolidated Balance Sheets FINANCIAL INSTRUMENTS CASH COLLATERAL NET AMOUNT Derivatives $ (5,280 ) $ — $ (5,280 ) $ 5,280 $ — $ —
Schedule of offsetting liabilities	The table below presents a gross presentation, the effects of offsetting, and a net presentation of the Company's derivatives as of December 31, 2019. The net amounts of derivative liabilities can be reconciled to the tabular disclosure of fair value. The tabular disclosure of fair value provides the location that derivative liabilities are presented on the Company's Consolidated Balance Sheets. Offsetting of Derivative Liabilities GROSS AMOUNTS of recognized liabilities GROSS AMOUNTS OFFSET in the Consolidated Balance Sheets NET AMOUNTS OF LIABILITIES presented in the Consolidated Balance Sheets GROSS AMOUNTS NOT OFFSET in the Consolidated Balance Sheets FINANCIAL INSTRUMENTS CASH COLLATERAL NET AMOUNT Derivatives $ (5,280 ) $ — $ (5,280 ) $ 5,280 $ — $ —

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2019
Equity [Abstract]
Schedule of reconciliation of the beginning and ending common stock outstanding	The Company had no preferred shares outstanding and had common shares outstanding for the three years ended December 31, 2019 as follows: YEAR ENDED DECEMBER 31, 2019 2018 2017 Balance, beginning of year $ 125,279,455 $ 125,131,593 $ 116,416,900 Issuance of common stock 9,251,440 26,203 8,395,607 Non-vested share-based awards, net of withheld shares and forfeitures 175,259 121,659 319,086 Balance, end of year $ 134,706,154 $ 125,279,455 $ 125,131,593
Schedule of sale of stock under market equity offering Program	The following table details the shares sold under this program. SHARES SOLD SALE PRICE per share NET PROCEEDS in millions 2019 5,470,673 $32.01 - $33.77 $ 179.1 2018 — NA $ — 2017 — NA $ —
Schedule of reconciliation of beginning and ending balances of accumulated other comprehensive income	The following table represents the changes in accumulated other comprehensive loss during the years ended December 31, 2019 and 2018 : INTEREST RATE SWAPS as of December 31, Dollars in thousands 2019 2018 Beginning balance $ (902 ) $ (1,299 ) Other comprehensive loss before reclassifications 319 424 Amounts reclassified from accumulated other comprehensive income (loss) (5,592 ) (27 ) Net current-period other comprehensive (loss) income (5,273 ) 397 Ending balance $ (6,175 ) $ (902 )
Schedule of reclassifications out of accumulated other comprehensive income	The following table represents the details regarding the reclassifications from Accumulated other comprehensive income (loss) during the year ended December 31, 2019 (dollars in thousands): DETAILS ABOUT ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) COMPONENTS AMOUNT RECLASSIFIED from accumulated other comprehensive income (loss) AFFECTED LINE ITEM in the statement where net income is presented Amounts reclassified from accumulated other comprehensive income (loss) related to settled interest rate swaps $ 168 Interest Expense Amounts reclassified from accumulated other comprehensive income (loss) related to current interest rate swaps 151 Interest Expense $ 319

Stock and Other Incentive Pla_2

Stock and Other Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2019
Share-based Payment Arrangement [Abstract]
Schedule of unrecognized compensation cost, nonvested awards	he following table represents expected amortization of the Company's non-vested shares issued: Dollars in millions FUTURE AMORTIZATION of non-vested shares 2020 $ 8.7 2021 7.3 2022 5.9 2023 3.8 2024 2.5 2025 and thereafter 1.9 Total $ 30.1
Schedule of the activity under the incentive plan the previous directors' plan	A summary of the activity under the 2015 Incentive Plan and related information for the three years in the period ended December 31, 2019 follows: YEAR ENDED DECEMBER 31, Dollars in thousands, except per share data 2019 2018 2017 Share-based awards, beginning of year 1,769,863 1,907,645 1,786,497 Granted 276,839 273,012 413,489 Vested (292,636 ) (410,794 ) (292,341 ) Share-based awards, end of year 1,754,066 1,769,863 1,907,645 Weighted-average grant date fair value of Share-based awards, beginning of year $ 29.36 $ 28.44 $ 27.18 Share-based awards granted during the year $ 31.75 $ 29.72 $ 32.05 Share-based awards vested during the year $ 28.84 $ 25.32 $ 25.88 Share-based awards, end of year $ 29.82 $ 29.36 $ 28.44 Grant date fair value of shares granted during the year $ 8,791 $ 8,114 $ 13,254
Schedule of the employee stock purchase plan activity	A summary of the Employee Stock Purchase Plan activity and related information for the three years in the period ended December 31, 2019 is as follows: YEAR ENDED DECEMBER 31, Dollars in thousands, except per share data 2019 2018 2017 Options outstanding, beginning of year 328,533 318,100 316,321 Granted 235,572 203,836 206,824 Exercised (35,277 ) (16,716 ) (32,076 ) Forfeited (54,095 ) (40,897 ) (40,659 ) Expired (142,074 ) (135,790 ) (132,310 ) Options outstanding and exercisable, end of year 332,659 328,533 318,100 Weighted-average exercise price of Options outstanding, beginning of year $ 24.17 $ 25.00 $ 23.69 Options granted during the year $ 24.17 $ 27.30 $ 25.77 Options exercised during the year $ 25.01 $ 24.01 $ 24.31 Options forfeited during the year $ 25.26 $ 24.06 $ 25.01 Options expired during the year $ 25.77 $ 23.55 $ 23.22 Options outstanding, end of year $ 25.59 $ 24.17 $ 25.00 Weighted-average fair value of options granted during the year (calculated as of the grant date) $ 7.02 $ 7.81 $ 6.31 Intrinsic value of options exercised during the year $ 269 $ 71 $ 271 Intrinsic value of options outstanding and exercisable (calculated as of December 31) $ 2,589 $ 1,402 $ 2,683 Exercise prices of options outstanding (calculated as of December 31) $ 25.59 $ 24.17 $ 25.00 Weighted-average contractual life of outstanding options (calculated as of December 31, in years) 0.8 0.8 0.8
Schedule of fair value of options issued based on weighted-average assumptions	2019 2018 2017 Risk-free interest rates 2.48 % 1.89 % 1.20 % Expected dividend yields 4.19 % 3.66 % 3.70 % Expected life (in years) 1.45 1.45 1.45 Expected volatility 29.8 % 28.4 % 20.4 % Expected forfeiture rates 85 % 85 % 85 %

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2019
Earnings Per Share [Abstract]
Schedule of earnings per share	The table below sets forth the computation of basic and diluted earnings per common share for the three years in the period ended December 31, 2019 . YEAR ENDED DECEMBER 31, Dollars in thousands, except per share data 2019 2018 2017 Weighted average common shares Weighted average common shares outstanding 129,735,723 125,219,773 119,739,216 Non-vested shares (1,736,022 ) (1,927,648 ) (1,813,058 ) Weighted average common shares - basic 127,999,701 123,292,125 117,926,158 Weighted average common shares - basic 127,999,701 123,292,125 117,926,158 Dilutive effect of employee stock purchase plan 84,283 58,808 91,007 Weighted average common shares - diluted 128,083,984 123,350,933 118,017,165 Net income $ 39,185 $ 69,771 $ 23,092 Dividends paid on nonvested share-based awards (2,075 ) (2,320 ) (2,149 ) Net income applicable to common stockholders $ 37,110 $ 67,451 $ 20,943 Basic earnings per common share $ 0.29 $ 0.55 $ 0.18 Diluted earnings per common share $ 0.29 $ 0.55 $ 0.18

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Schedule of construction activity	The table below details the Company’s construction activity as of December 31, 2019 . The information included in the table below represents management’s estimates and expectations at December 31, 2019 , which are subject to change. The Company’s disclosures regarding certain projections or estimates of completion dates may not reflect actual results. DECEMBER 31, 2019 ESTIMATED REMAINING FUNDINGS unaudited ESTIMATED TOTAL INVESTMENT unaudited APPROXIMATE SQUARE FEET unaudited Dollars in thousands NUMBER OF PROPERTIES INITIAL OCCUPANCY CONSTRUCTION IN PROGRESS BALANCE TOTAL FUNDED during the year TOTAL AMOUNT FUNDED Construction Activity Seattle, WA 1 Q1 2020 $ 48,731 $ 25,211 $ 49,033 $ 15,087 $ 64,120 151,000 Redevelopment Activity Memphis, TN 1 1 Q1 2021 — 9,032 9,032 18,768 27,800 110,883 Total $ 48,731 $ 34,243 $ 58,065 $ 33,855 $ 91,920 261,883 1 Initial occupancy represents the quarter in which the redevelopment is expected to be completed. The building will continue to operate with in-place leases during construction.

Other Data (Tables)

Other Data (Tables)	12 Months Ended
	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Schedule of taxable income	The following table reconciles the Company’s consolidated net income attributable to common stockholders to taxable income for the three years ended December 31, 2019 : YEAR ENDED DECEMBER 31, Dollars in thousands 2019 2018 2017 Net income $ 39,185 $ 69,771 $ 23,092 Reconciling items to taxable income Depreciation and amortization 67,953 64,775 46,426 Gain or loss on disposition of depreciable assets (15,689 ) (27,581 ) 1,570 Straight-line rent (11,535 ) (3,049 ) (4,551 ) Receivable allowances 1,942 2,470 1,680 Share-based compensation 2,628 (1,699 ) 1,855 Other 12,631 842 6,552 57,930 35,758 53,532 Taxable income 1 $ 97,115 $ 105,529 $ 76,624 Dividends paid $ 155,358 $ 150,266 $ 142,327 1
Schedule of characterization of distributions on common stock	For the three years ended December 31, 2019 , there were no preferred shares outstanding. As such, no dividends were distributed related to preferred shares for those periods. 2019 2018 2017 PER SHARE % PER SHARE % PER SHARE % Common stock Ordinary income 1 $ 0.79 65.7 % $ 0.75 62.2 % $ 0.42 34.5 % Return of capital 0.40 33.9 % 0.33 27.8 % 0.50 42.0 % Unrecaptured section 1250 gain 0.01 0.4 % 0.12 10.0 % 0.28 23.5 % Common stock distributions $ 1.20 100.0 % $ 1.20 100.0 % $ 1.20 100.0 % 1 For the 2018 reporting year all ordinary income is also Code Section 199A eligible per the The Tax Cut and Jobs Act of 2017.
Schedule of state income taxes	State income tax expense and state income tax payments for the three years ended December 31, 2019 are detailed in the table below: YEAR ENDED DECEMBER 31, Dollars in thousands 2019 2018 2017 State income tax expense Texas gross margins tax $ 550 $ 586 $ 608 Total state income tax expense $ 550 $ 586 $ 608 State income tax payments, net of refunds and collections $ 543 $ 637 $ 555

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2019
Fair Value Disclosures [Abstract]
Schedule of fair value and carrying values for notes and bonds payable, mortgage notes receivable and notes receivable	The table below details the fair value and carrying values for notes and bonds payable as of December 31, 2019 and 2018 . DECEMBER 31, 2019 DECEMBER 31, 2018 Dollars in millions CARRYING VALUE FAIR VALUE CARRYING VALUE FAIR VALUE Notes and bonds payable 1 $ 1,414.1 $ 1,425.8 $ 1,346.0 $ 1,326.5 1 Level 2 – model-derived valuations in which significant inputs and significant value drivers are observable in active markets.

Selected Quarterly Financial _2

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2019
Selected Quarterly Financial Information [Abstract]
Schedule of quarterly financial information	Quarterly financial information for the year ended December 31, 2019 is summarized below. QUARTER ENDED Dollars in thousands, except per share data MARCH 31 JUNE 30 SEPTEMBER 30 DECEMBER 31 1 2019 Revenues $ 112,657 $ 116,317 $ 119,799 $ 121,524 Net income attributable to common stockholders $ 4,891 $ 4,484 $ 2,601 $ 27,210 Net income attributable to common stockholders per share Basic earnings per common share $ 0.04 $ 0.03 $ 0.02 $ 0.20 Diluted earnings per common share $ 0.04 $ 0.03 $ 0.02 $ 0.20 1 The increases in net income and amounts per share for the fourth quarter of 2019 are primarily attributable to gains of $20.0 million on the sale of six properties. Quarterly financial information for the year ended December 31, 2018 is summarized below. QUARTER ENDED Dollars in thousands, except per share data MARCH 31 JUNE 30 1 SEPTEMBER 30 DECEMBER 31 2 2018 Revenues $ 112,124 $ 111,634 $ 113,462 $ 113,168 Net income attributable to common stockholders $ 9,180 $ 37,729 $ 6,548 $ 16,314 Net income attributable to common stockholders per share Basic earnings per common share $ 0.07 $ 0.30 $ 0.05 $ 0.13 Diluted earnings per common share $ 0.07 $ 0.30 $ 0.05 $ 0.13 1 The increases in net income and amounts per share for the second quarter of 2018 are primarily attributable to gains of $27.7 million on the sale of twelve properties. 2 The increases in net income and amounts per share for the fourth quarter of 2018 are primarily attributable to gains of $10.8 million on the sale of three

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details) ft² in Millions	Jan. 01, 2019USD ($)	Dec. 31, 2019USD ($)ft²land_parcelreporting_unitstateproperty	Dec. 31, 2018USD ($)property	Dec. 31, 2017USD ($)property
Business Overview [Abstract]
Gross investment, amount, total		$ 4,400,000,000
Real estate properties and mortgages | property		204
Number of owned real estate properties | property		204
Number of states that the Company owns real estate in | state		25
Square footage of owned real estate properties | ft²		15.4
Approximate square feet for which Nationwide property management services provided by company | ft²		11.4
Segment Reporting [Abstract]
Number of Reporting Units | reporting_unit		1
Real Estate Properties [Abstract]
Total real estate properties		$ 4,359,993,000	$ 3,974,071,000
Elimination of real estate lease intangibles against accumulated depreciation		28,000,000	23,200,000
Depreciation		$ 152,600,000	143,800,000	$ 129,400,000
Maximum period up to which interest capitalize on properties in stabilization		1 year
Land Held for Development [Abstract]
Number of land parcels held for development | land_parcel		7
Land held for development		$ 24,600,000	24,600,000
Goodwill and Intangible Assets [Abstract]
Goodwill impairment loss		0	0
Goodwill		3,500,000	$ 3,487,000
Other Operating Income [Abstract]
Number of owned real estate properties to which property operating agreements between company and sponsoring health system is applicable | property			1	1
Federal Income Taxes [Abstract]
Provision for federal income tax		$ 0
Percentage of distribution of taxable income for qualify as REIT		90.00%
Lease liabilities		$ 91,574,000
Maximum [Member]
Federal Income Taxes [Abstract]
Ground lease, initial term		99 years	75 years
Minimum [Member]
Federal Income Taxes [Abstract]
Ground lease, initial term		40 years	50 years
Other Assets [Member]
Federal Income Taxes [Abstract]
Transfers to operating lease, right-of-use assets	$ 45,000,000
Other Liabilities [Member]
Federal Income Taxes [Abstract]
Transfers to operating lease, right-of-use assets	1,900,000
Accounts Payable and Accrued Liabilities [Member]
Federal Income Taxes [Abstract]
Transfers to operating lease, right-of-use assets	8,400,000
Forward Starting Interest Rate Swap [Member]
Derivative Instrument Detail [Abstract]
Accumulated other comprehensive income (loss), net of tax		$ 6,200,000	$ 900,000
Tenant and Capital Improvements [Member]
Real Estate Properties [Abstract]
Fully depreciated tenant and capital improvements eliminated against accumulated depreciation		1,300,000	500,000
At Market Lease Intangibles [Member]
Real Estate Properties [Abstract]
Elimination of real estate lease intangibles against accumulated depreciation		$ 17,200,000	$ 9,900,000
Accounting Standards Update 2016-02 [Member]
Federal Income Taxes [Abstract]
Lease liabilities	$ 91,700,000
Accounting Standards Update 2016-02 [Member] | Maximum [Member]
Federal Income Taxes [Abstract]
Ground lease, initial term		52 years 1 month 6 days
Operating lease, discount rate (percent)			6.20%
Ground lease, discount rate			6.20%
Accounting Standards Update 2016-02 [Member] | Minimum [Member]
Federal Income Taxes [Abstract]
Operating lease, discount rate (percent)			3.80%
Ground lease, discount rate			3.80%

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Useful lives of real estate assets and liabilities (Details)	12 Months Ended
	Dec. 31, 2019
Lease intangibles (including ground lease intangibles) | Minimum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	2 years 1 month 6 days
Intangible asset useful life	2 years 1 month 6 days
Lease intangibles (including ground lease intangibles) | Maximum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	99 years
Intangible asset useful life	99 years
Land improvements | Minimum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	3 years
Land improvements | Maximum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	39 years
Building and improvements | Minimum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	3 years 3 months 18 days
Building and improvements | Maximum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	39 years
Personal property | Minimum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	2 years 9 months 18 days
Personal property | Maximum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	20 years

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Other operating	$ 8,073	$ 7,992	$ 7,759
Parking income
Disaggregation of Revenue [Line Items]
Other operating	7,520	6,930	6,611
Property lease guaranty income
Disaggregation of Revenue [Line Items]
Other operating	128	675	726
Management fee income
Disaggregation of Revenue [Line Items]
Other operating	270	273	308
Miscellaneous
Disaggregation of Revenue [Line Items]
Other operating	$ 155	$ 114	$ 114

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Components of rental income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Property operating income	$ 415,142	$ 390,256	$ 358,009
Single-tenant net lease	44,083	47,860	52,897
Straight-line rent	3,000	4,281	6,072
Rental income	$ 462,225
Rental income		$ 442,397	$ 416,978

Property Investments (Details)

Property Investments (Details) $ in Thousands	Dec. 31, 2019USD ($)property	Dec. 31, 2018USD ($)
Summary of Company's investment
NUMBER of properties | property	204
Number of real estate investments | property	204
Land	$ 314,398
Buildings, improvements and lease intangibles	3,986,326	$ 3,675,415
Buildings, Improvements, and Lease Intangibles, including Construction in Progress	4,035,057
Personal property	10,538	10,696
Total real estate properties	4,359,993	3,974,071
Total real estate investments	4,359,993
Accumulated Depreciation	(1,121,102)	$ (1,015,174)
Memphis Redevelopment [Member]
Summary of Company's investment
Land	5,222
Buildings, improvements and lease intangibles	3,810
Personal property	0
Total real estate properties	9,032
Accumulated Depreciation	$ (50)
Land Held for Development [Member]
Summary of Company's investment
NUMBER of properties | property	0
Land	$ 24,647
Buildings, improvements and lease intangibles	0
Personal property	0
Total real estate properties	24,647
Accumulated Depreciation	(671)
Construction in Progress [Member]
Summary of Company's investment
Land	0
Buildings, improvements and lease intangibles	48,731
Personal property	0
Total real estate properties	48,731
Accumulated Depreciation	$ 0
Corporate Property [Member]
Summary of Company's investment
NUMBER of properties | property	0
Land	$ 0
Buildings, improvements and lease intangibles	0
Personal property	5,500
Total real estate properties	5,500
Accumulated Depreciation	$ (4,686)
Medical office/outpatient [Member]
Summary of Company's investment
NUMBER of properties | property	204
Land	$ 284,529
Buildings, improvements and lease intangibles	3,982,516
Personal property	5,038
Total real estate properties	4,272,083
Accumulated Depreciation	$ (1,115,695)
Medical office/outpatient [Member] | Washington [Member]
Summary of Company's investment
NUMBER of properties | property	25
Land	$ 58,565
Buildings, improvements and lease intangibles	532,767
Personal property	421
Total real estate properties	591,753
Accumulated Depreciation	$ (88,890)
Medical office/outpatient [Member] | Dallas, Texas [Member]
Summary of Company's investment
NUMBER of properties | property	25
Land	$ 19,194
Buildings, improvements and lease intangibles	496,683
Personal property	442
Total real estate properties	516,319
Accumulated Depreciation	$ (181,556)
Medical office/outpatient [Member] | Los Angeles, California [Member]
Summary of Company's investment
NUMBER of properties | property	14
Land	$ 44,386
Buildings, improvements and lease intangibles	205,829
Personal property	347
Total real estate properties	250,562
Accumulated Depreciation	$ (95,979)
Medical office/outpatient [Member] | Georgia [Member]
Summary of Company's investment
NUMBER of properties | property	9
Land	$ 3,679
Buildings, improvements and lease intangibles	212,509
Personal property	84
Total real estate properties	216,272
Accumulated Depreciation	$ (20,040)
Medical office/outpatient [Member] | Nashville, Tennessee [Member]
Summary of Company's investment
NUMBER of properties | property	6
Land	$ 20,053
Buildings, improvements and lease intangibles	180,463
Personal property	1,109
Total real estate properties	201,625
Accumulated Depreciation	$ (64,038)
Medical office/outpatient [Member] | North Carolina [Member]
Summary of Company's investment
NUMBER of properties | property	16
Land	$ 4,200
Buildings, improvements and lease intangibles	176,261
Personal property	105
Total real estate properties	180,566
Accumulated Depreciation	$ (67,040)
Medical office/outpatient [Member] | Colorado [Member]
Summary of Company's investment
NUMBER of properties | property	9
Land	$ 16,514
Buildings, improvements and lease intangibles	134,004
Personal property	271
Total real estate properties	150,789
Accumulated Depreciation	$ (25,265)
Medical office/outpatient [Member] | Washington, D.C. [Member]
Summary of Company's investment
NUMBER of properties | property	6
Land	$ 0
Buildings, improvements and lease intangibles	150,304
Personal property	21
Total real estate properties	150,325
Accumulated Depreciation	$ (25,097)
Medical office/outpatient [Member] | Virginia [Member]
Summary of Company's investment
NUMBER of properties | property	7
Land	$ 0
Buildings, improvements and lease intangibles	149,132
Personal property	106
Total real estate properties	149,238
Accumulated Depreciation	$ (44,204)
Medical office/outpatient [Member] | Houston, Texas [Member]
Summary of Company's investment
NUMBER of properties | property	9
Land	$ 16,211
Buildings, improvements and lease intangibles	132,013
Personal property	78
Total real estate properties	148,302
Accumulated Depreciation	$ (44,229)
Medical office/outpatient [Member] | Hawaii [Member]
Summary of Company's investment
NUMBER of properties | property	3
Land	$ 8,327
Buildings, improvements and lease intangibles	135,641
Personal property	159
Total real estate properties	144,127
Accumulated Depreciation	$ (39,165)
Medical office/outpatient [Member] | Iowa [Member]
Summary of Company's investment
NUMBER of properties | property	7
Land	$ 12,665
Buildings, improvements and lease intangibles	126,401
Personal property	99
Total real estate properties	139,165
Accumulated Depreciation	$ (34,725)
Medical office/outpatient [Member] | Oklahoma [Member]
Summary of Company's investment
NUMBER of properties | property	4
Land	$ 10,401
Buildings, improvements and lease intangibles	115,706
Personal property	15
Total real estate properties	126,122
Accumulated Depreciation	$ (19,351)
Medical office/outpatient [Member] | Indiana [Member]
Summary of Company's investment
NUMBER of properties | property	4
Land	$ 3,299
Buildings, improvements and lease intangibles	118,847
Personal property	0
Total real estate properties	122,146
Accumulated Depreciation	$ (26,082)
Medical office/outpatient [Member] | San Francisco, California [Member]
Summary of Company's investment
NUMBER of properties | property	3
Land	$ 14,054
Buildings, improvements and lease intangibles	107,396
Personal property	43
Total real estate properties	121,493
Accumulated Depreciation	$ (20,906)
Medical office/outpatient [Member] | Missouri [Member]
Summary of Company's investment
NUMBER of properties | property	1
Land	$ 1,989
Buildings, improvements and lease intangibles	109,304
Personal property	0
Total real estate properties	111,293
Accumulated Depreciation	$ (17,740)
Medical office/outpatient [Member] | Austin, Texas [Member]
Summary of Company's investment
NUMBER of properties | property	5
Land	$ 14,236
Buildings, improvements and lease intangibles	92,809
Personal property	123
Total real estate properties	107,168
Accumulated Depreciation	$ (24,048)
Medical office/outpatient [Member] | Memphis, Tennessee [Member]
Summary of Company's investment
NUMBER of properties | property	7
Land	$ 5,241
Buildings, improvements and lease intangibles	92,508
Personal property	194
Total real estate properties	97,943
Accumulated Depreciation	$ (37,582)
Medical office/outpatient [Member] | San Antonio, Texas [Member]
Summary of Company's investment
NUMBER of properties | property	6
Land	$ 6,487
Buildings, improvements and lease intangibles	88,583
Personal property	404
Total real estate properties	95,474
Accumulated Depreciation	$ (40,573)
Medical office/outpatient [Member] | Illinois [Member]
Summary of Company's investment
NUMBER of properties | property	3
Land	$ 5,859
Buildings, improvements and lease intangibles	87,588
Personal property	211
Total real estate properties	93,658
Accumulated Depreciation	$ (23,540)
Medical office/outpatient [Member] | Minnesota [Member]
Summary of Company's investment
NUMBER of properties | property	4
Land	$ 2,090
Buildings, improvements and lease intangibles	62,359
Personal property	0
Total real estate properties	64,449
Accumulated Depreciation	$ (10,486)
Medical office/outpatient [Member] | Other (16 markets) [Member]
Summary of Company's investment
NUMBER of properties | property	31
Land	$ 17,079
Buildings, improvements and lease intangibles	475,409
Personal property	806
Total real estate properties	493,294
Accumulated Depreciation	$ (165,159)

Leases - Narrative (Details)

Leases - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)renewal_option	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Leases [Abstract]
Rental income	$ 462,225
Rental income		$ 442,397	$ 416,978
Approximate Investment in real estate properties subject to outstanding contractual option to purchase	$ 96,000
Number of exercisable purchase options | renewal_option	4

Leases - Non-cancelable Operati

Leases - Non-cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2019USD ($)
Leases [Abstract]
2020	$ 360,340
2021	315,426
2022	275,798
2023	233,424
2024	177,738
2025 and thereafter	501,849
Lease payments receivable	$ 1,864,575

Leases - Lease Payments Receiva

Leases - Lease Payments Receivable under Topic 840 (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 326,441
2020	279,211
2021	235,660
2022	201,072
2023	163,978
2024 and thereafter	476,673
Total	$ 1,683,035

Leases - Ground Leases (Details

Leases - Ground Leases (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2019USD ($)	Dec. 31, 2019ft²propertyLease	Dec. 31, 2018ft²renewal_optionLease
Lessee, Lease, Description [Line Items]
Number of properties subject to ground leases		108	107
Square feet subject to ground leases | ft²		8.9	8,800,000
Number of ground leases prepaid		46
Number of ground leases, excluding prepaid leases		62	60
Amortization of prepaid rent | $	$ 0.6
Minimum [Member]
Lessee, Lease, Description [Line Items]
Ground lease, initial term		40 years	50 years
Ground lease, number of renewal options | renewal_option			1
Ground lease, renewal term			75 years
Maximum [Member]
Lessee, Lease, Description [Line Items]
Ground lease, initial term		99 years	75 years
Ground lease, renewal term			100 years
Weighted Average [Member]
Lessee, Lease, Description [Line Items]
Ground lease, initial term			53 years 10 months 24 days

Leases - Future Minimum Lease P

Leases - Future Minimum Lease Payments (Details) $ in Thousands	Dec. 31, 2019USD ($)
Operating
2020	$ 4,814
2021	4,844
2022	4,875
2023	4,913
2024	4,969
2025 and thereafter	307,665
Total undiscounted lease payments	332,080
Discount	(240,506)
Lease liabilities	91,574
Financing
2020	746
2021	754
2022	763
2023	774
2024	795
2025 and thereafter	83,404
Total undiscounted lease payments	87,236
Discount	(69,199)
Lease liabilities	$ 18,037

Leases - Future Minimum Lease_2

Leases - Future Minimum Lease Payments under ASC 840 (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2019	$ 5,288
2020	5,260
2021	5,238
2022	5,207
2023	5,224
2024 and thereafter	323,533
Total	$ 349,750

Leases - Lease Cost (Details)

Leases - Lease Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2017
Operating lease cost
Operating lease expense	$ 4,623
Variable lease expense	3,161
Finance lease cost
Amortization of right-of-use assets	165
Interest on lease liabilities	616
Total lease expense	8,565
Other information
Operating cash flows outflows related to operating leases	6,972
Financing cash flows outflows related to financing leases	379	$ 0
Right-of-use assets obtained in exchange for new finance lease liabilities	$ 17,800
Weighted-average remaining lease term (excluding renewal options) - operating leases	49 years 6 months
Weighted-average remaining lease term (excluding renewal options) -finance leases	65 years 2 months 12 days
Weighted-average discount rate - operating leases	5.70%
Weighted-average discount rate - finance leases	5.40%

Acquisitions, Dispositions an_3

Acquisitions, Dispositions and Mortgage Repayments - Acquisitions (Details) $ in Thousands	Dec. 18, 2019USD ($)ft²	Dec. 13, 2019USD ($)ft²	Dec. 10, 2019USD ($)ft²	Nov. 18, 2019USD ($)ft²	Oct. 31, 2019USD ($)ft²	Sep. 30, 2019USD ($)ft²property	Sep. 26, 2019USD ($)ft²	Aug. 01, 2019USD ($)ft²	Jun. 28, 2019USD ($)ft²	Jun. 14, 2019USD ($)ft²	Jun. 11, 2019USD ($)ft²	Jun. 10, 2019USD ($)ft²	Apr. 02, 2019USD ($)ft²	Mar. 28, 2019USD ($)ft²propertyLease	Dec. 19, 2018USD ($)ft²	Dec. 14, 2018USD ($)ft²	Aug. 24, 2018USD ($)ft²	Jun. 29, 2018USD ($)ft²	May 21, 2018USD ($)ft²	May 18, 2018USD ($)ft²	May 04, 2018USD ($)ft²	Dec. 31, 2019USD ($)ft²property	Dec. 31, 2018USD ($)ft²Lease
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Purchase price																						$ 381,300
Cash consideration																						378,500
Real estate																						384,700
Other																						$ (6,200)
Square footage | ft²																						1,086,712
Number of properties subject to ground leases																						108	107
Financing lease liabilities																						$ 18,037
Above-market lease intangibles																						1,200	$ 16,800
Ground leases																						9,400	9,900
2018 Real estate acquisitions [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Purchase price																							111,500
Mortgage notes payable assumed																							(8,000)
Cash consideration																							103,100
Real estate																							112,400
Other																							$ (1,200)
Square footage | ft²																							511,422
Unamortized premium of notes assumed																							$ 100
Medical Office Building [Member] | Washington, D.C. [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired														Mar. 28, 2019
Purchase price														$ 46,000
Cash consideration														45,900
Real estate														50,200
Other														$ (4,300)
Square footage | ft²														158,338
Number of properties acquired | property														2
Number of properties subject to ground leases | Lease														2
Financing lease liabilities																						14,300
Above-market lease intangibles																						$ 5,200
Medical Office Building [Member] | Indiana [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired														Mar. 28, 2019
Purchase price														$ 47,000
Cash consideration														44,800
Real estate														43,700
Other														$ 1,100
Square footage | ft²														143,499
Ground leases														$ 800
Below-market lease intangible														$ 900
Medical Office Building [Member] | Georgia [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired													Apr. 2, 2019
Purchase price													$ 28,000
Cash consideration													28,000
Real estate													28,000
Other													$ 0
Square footage | ft²													47,963
Medical Office Building [Member] | Dallas, Texas [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired					Oct. 31, 2019							Jun. 10, 2019
Purchase price					$ 20,100							$ 17,000
Cash consideration					19,500							16,700
Real estate					20,200							17,000
Other					$ (700)							$ (300)
Square footage | ft²					48,192							89,990
Present value of future lease payments					$ 3,600
Medical Office Building [Member] | Washington [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired	Dec. 18, 2019		Dec. 10, 2019	Nov. 18, 2019					Jun. 28, 2019	Jun. 14, 2019	Jun. 11, 2019
Purchase price	$ 10,000		$ 24,200	$ 22,800					$ 30,500	$ 19,000	$ 7,700
Cash consideration	9,300		24,500	23,100					30,400	19,100	7,800
Real estate	9,900		24,600	23,200					30,600	19,500	7,800
Other	$ (600)		$ (100)	$ (100)					$ (200)	$ (400)	$ 0
Square footage | ft²	20,109		44,166	36,350					78,288	47,255	29,870
Medical Office Building [Member] | Houston, Texas [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired								Aug. 1, 2019
Purchase price								$ 13,500
Cash consideration								13,500
Real estate								13,500
Other								$ 0
Square footage | ft²								29,903
Medical Office Building [Member] | Oklahoma [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired							Sep. 26, 2019
Purchase price							$ 4,100
Cash consideration							4,100
Real estate							4,100
Other							$ 0
Square footage | ft²							28,542
Medical Office Building [Member] | California [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired						Sep. 30, 2019
Purchase price						$ 61,100
Cash consideration						60,900
Real estate						61,800
Other						$ (900)
Square footage | ft²						115,634
Number of properties acquired | property						2
Medical Office Building [Member] | North Carolina [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired					Oct. 31, 2019
Purchase price					$ 21,600
Cash consideration					22,000
Real estate					21,700
Other					$ 300
Square footage | ft²					57,730
Medical Office Building [Member] | Tennessee [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired		Dec. 13, 2019
Purchase price		$ 8,700
Cash consideration		8,900
Real estate		8,900
Other		$ 0
Square footage | ft²		110,883
Medical Office Building [Member] | 2018 Real estate acquisitions [Member] | Washington [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired																		Jun. 29, 2018			May 4, 2018
Purchase price																		$ 26,200			$ 7,800
Mortgage notes payable assumed																		0			0
Cash consideration																		26,200			7,800
Real estate																		26,700			7,800
Other																		$ (500)			$ 0
Square footage | ft²																		86,942			13,314
Medical Office Building [Member] | 2018 Real estate acquisitions [Member] | Colorado [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired																	Aug. 24, 2018			May 18, 2018
Purchase price																	$ 4,100			$ 12,100
Mortgage notes payable assumed																	0			(8,000)
Cash consideration																	4,200			3,800
Real estate																	4,200			12,100
Other																	$ 0			$ (200)
Square footage | ft²																	17,084			93,992
Medical Office Building [Member] | 2018 Real estate acquisitions [Member] | Oklahoma [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired																			May 21, 2018
Purchase price																			$ 11,400
Mortgage notes payable assumed																			0
Cash consideration																			11,400
Real estate																			11,500
Other																			$ (100)
Square footage | ft²																			82,647
Medical Office Building [Member] | 2018 Real estate acquisitions [Member] | Illinois [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired															Dec. 19, 2018
Purchase price															$ 5,100
Mortgage notes payable assumed															0
Cash consideration															4,900
Real estate															5,100
Other															$ (200)
Square footage | ft²															14,883
Office Building [Member] | 2018 Real estate acquisitions [Member] | Colorado [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired																				May 18, 2018
Purchase price																				$ 12,900
Mortgage notes payable assumed																				0
Cash consideration																				12,800
Real estate																				13,000
Other																				$ (200)
Square footage | ft²																				93,869
Office Building [Member] | 2018 Real estate acquisitions [Member] | Tennessee [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date acquired																Dec. 4, 2018
Purchase price																$ 31,900
Mortgage notes payable assumed																0
Cash consideration																32,000
Real estate																32,000
Other																$ 0
Square footage | ft²																108,691

Acquisitions, Dispositions an_4

Acquisitions, Dispositions and Mortgage Repayments - Assets Acquired and Liabilities Assumed (Details) $ in Millions	Jan. 03, 2020USD ($)ft²	Dec. 31, 2019USD ($)ft²	Dec. 31, 2018USD ($)
Business Acquisition [Line Items]
Building		$ 270.7	$ 64
Land		59.1	31.4
Land improvements		4.2	2.7
Mortgage notes payable assumed, including fair value adjustments			(8)
Other assets acquired		2.3	0.2
Accounts payable, accrued liabilities and other liabilities assumed		(4.3)	(1.4)
Total cash paid		$ 378.5	103.1
Approximate square feet | ft²		15,400,000
Subsequent Event [Member]
Business Acquisition [Line Items]
Approximate square feet | ft²	86,986
Purchase price	$ 42
At Market Lease Intangibles [Member]
Business Acquisition [Line Items]
Intangibles		$ 50.7	14.3
Above-market Lease Intangibles (Lessor) [Member]
Business Acquisition [Line Items]
Intangibles		0.7
Below-market Lease Intangibles (Lessor) [Member]
Business Acquisition [Line Items]
Intangible liabilities		(0.7)	$ (0.1)
Intangible asset useful life			3 years 9 months 18 days
Above- Market Lease Intangibles (Lessee) [Member]
Business Acquisition [Line Items]
Intangible liabilities		(5.1)
Below-Market Lease Intangibles (Lessee) [Member]
Business Acquisition [Line Items]
Intangibles		$ 0.9
Intangible asset useful life		65 years 1 month 6 days
Minimum [Member] | At Market Lease Intangibles [Member]
Business Acquisition [Line Items]
Intangible asset useful life		3 years 3 months 19 days	1 year 3 months 18 days
Minimum [Member] | Above-market Lease Intangibles (Lessor) [Member]
Business Acquisition [Line Items]
Intangible asset useful life		2 years 4 months 24 days
Minimum [Member] | Below-market Lease Intangibles (Lessor) [Member]
Business Acquisition [Line Items]
Intangible asset useful life		1 year 2 months 12 days
Minimum [Member] | Above- Market Lease Intangibles (Lessee) [Member]
Business Acquisition [Line Items]
Intangible asset useful life		69 years 1 month 6 days
Minimum [Member] | Building [Member]
Business Acquisition [Line Items]
Asset estimated useful life		8 years	20 years
Minimum [Member] | Land Improvements
Business Acquisition [Line Items]
Asset estimated useful life		3 years	5 years
Maximum [Member] | At Market Lease Intangibles [Member]
Business Acquisition [Line Items]
Intangible asset useful life		9 years 2 months 12 days	4 years 2 months 12 days
Maximum [Member] | Above-market Lease Intangibles (Lessor) [Member]
Business Acquisition [Line Items]
Intangible asset useful life		9 years 10 months 25 days
Maximum [Member] | Below-market Lease Intangibles (Lessor) [Member]
Business Acquisition [Line Items]
Intangible asset useful life		8 years 7 months 6 days
Maximum [Member] | Above- Market Lease Intangibles (Lessee) [Member]
Business Acquisition [Line Items]
Intangible asset useful life		72 years 3 months 18 days
Maximum [Member] | Building [Member]
Business Acquisition [Line Items]
Asset estimated useful life		37 years	30 years
Maximum [Member] | Land Improvements
Business Acquisition [Line Items]
Asset estimated useful life		12 years	13 years 6 months

Acquisitions, Dispositions an_5

Acquisitions, Dispositions and Mortgage Repayments - Narrative (Details) $ in Millions	Jun. 29, 2018USD ($)a	Dec. 31, 2019USD ($)ft²	Dec. 31, 2018USD ($)
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Area of land | ft²		15,400,000
Net real estate investment		$ 25.8	$ 54.5
Gain on disposition of property		$ 25.1	$ 39.8
Medical Office Building [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Area of land | ft²		261,883
812930 Parking Lots and Garages [Member] | Real Estate Dispositions [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Net real estate investment	$ 3.9
Gain on disposition of property	$ 1.9
Real Estate Acquisitions [Member] | Land Held for Development [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Area of land | a	20.5
Appraised value of land	$ 5.8
Real Estate Acquisitions [Member] | Medical Office Building [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Area of land | a	4.6

Acquisitions, Dispositions an_6

Acquisitions, Dispositions and Mortgage Repayments - Dispositions (Details) $ in Millions	Dec. 30, 2019USD ($)ft²	Dec. 18, 2019USD ($)ft²	Nov. 27, 2019USD ($)ft²	Nov. 25, 2019USD ($)ft²	Oct. 25, 2019USD ($)ft²	Aug. 28, 2019USD ($)ft²	Aug. 01, 2019USD ($)ft²	Apr. 09, 2019USD ($)ft²	Dec. 27, 2018USD ($)ft²	Dec. 21, 2018USD ($)ft²	Dec. 20, 2018USD ($)ft²	Aug. 30, 2018USD ($)ft²	Jun. 27, 2018USD ($)ft²property	Apr. 26, 2018USD ($)ft²buildingproperty	Jun. 30, 2019USD ($)	Dec. 31, 2019USD ($)ft²	Dec. 31, 2018USD ($)ft²
Real Estate Dispositions [Line Items]
SALES PRICE																$ 54.9	$ 98.7
CLOSING ADJUSTMENTS																(2.5)	(1.9)
NET PROCEEDS																52.4	96.8
Net Real Estate Investment																25.8	54.5
OTHER including receivables																1.5	2.5
GAIN/ (IMPAIRMENT)																$ 25.1	$ 39.8
SQUARE FOOTAGE unaudited | ft²																537,050	806,206
Number of properties exercising purchase option | property														7
Number of single-tenant net leased buildings | building														5
Number of multi-tenant buildings | building														2
Arizona [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED								Apr. 9, 2019	Dec. 27, 2018
SALES PRICE								$ 13	$ 3
CLOSING ADJUSTMENTS								(0.9)	(0.2)
NET PROCEEDS								12.1	2.8
Net Real Estate Investment								6.9	1.9
OTHER including receivables								0.4	0.2
GAIN/ (IMPAIRMENT)								$ 4.8	$ 0.7
SQUARE FOOTAGE unaudited | ft²								67,345	37,310
Virginia [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED							Aug. 1, 2019							Apr. 26, 2018
SALES PRICE							$ 1.3							$ 46.2
CLOSING ADJUSTMENTS							(0.1)							0
NET PROCEEDS							1.2							46.2
Net Real Estate Investment							1.2							23.9
OTHER including receivables							0							0
GAIN/ (IMPAIRMENT)							$ 0							$ 22.3
SQUARE FOOTAGE unaudited | ft²							10,000							460,881
Impairment charge															$ 0.4
San Antonio, Texas [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED						Aug. 28, 2019
SALES PRICE						$ 0.9
CLOSING ADJUSTMENTS						(0.1)
NET PROCEEDS						0.8
Net Real Estate Investment						0.6
OTHER including receivables						0
GAIN/ (IMPAIRMENT)						$ 0.2
SQUARE FOOTAGE unaudited | ft²						10,138
Erie, ‎Pennsylvania [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED					Oct. 25, 2019
SALES PRICE					$ 14
CLOSING ADJUSTMENTS					0
NET PROCEEDS					14
Net Real Estate Investment					1.3
OTHER including receivables					0
GAIN/ (IMPAIRMENT)					$ 12.7
SQUARE FOOTAGE unaudited | ft²					90,123
Louisiana [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED				Nov. 25, 2019
SALES PRICE				$ 3.7
CLOSING ADJUSTMENTS				(0.2)
NET PROCEEDS				3.5
Net Real Estate Investment				1.2
OTHER including receivables				0.2
GAIN/ (IMPAIRMENT)				$ 2.1
SQUARE FOOTAGE unaudited | ft²				136,155
Tennessee [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED			Nov. 27, 2019							Dec. 21, 2018
SALES PRICE			$ 9.5							$ 13.3
CLOSING ADJUSTMENTS			(0.3)							(0.2)
NET PROCEEDS			9.2							13.1
Net Real Estate Investment			5							8.6
OTHER including receivables			1.3							0.4
GAIN/ (IMPAIRMENT)			$ 2.9							$ 4.1
SQUARE FOOTAGE unaudited | ft²			75,000							81,382
Pittsburgh, ‎Pennsylvania [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED		Dec. 18, 2019
SALES PRICE		$ 3.8
CLOSING ADJUSTMENTS		(0.3)
NET PROCEEDS		3.5
Net Real Estate Investment		3.5
OTHER including receivables		0
GAIN/ (IMPAIRMENT)		$ 0
SQUARE FOOTAGE unaudited | ft²		78,731
Impairment charge															$ 5.2
Dallas, Texas [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED	Dec. 30, 2019
SALES PRICE	$ 8.7
CLOSING ADJUSTMENTS	(0.6)
NET PROCEEDS	8.1
Net Real Estate Investment	6.1
OTHER including receivables	(0.4)
GAIN/ (IMPAIRMENT)	$ 2.4
SQUARE FOOTAGE unaudited | ft²	69,558
Michigan [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED													Jun. 27, 2018
SALES PRICE													$ 9.5
CLOSING ADJUSTMENTS													(0.7)
NET PROCEEDS													8.8
Net Real Estate Investment													3.4
OTHER including receivables													0
GAIN/ (IMPAIRMENT)													$ 5.4
SQUARE FOOTAGE unaudited | ft²													121,672
Number of properties exercising purchase option | property													5
Forfeited earnest money													$ 0.5
Missouri [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED												Aug. 30, 2018
SALES PRICE												$ 9.8
CLOSING ADJUSTMENTS												(0.5)
NET PROCEEDS												9.3
Net Real Estate Investment												7.5
OTHER including receivables												0.5
GAIN/ (IMPAIRMENT)												$ 1.3
SQUARE FOOTAGE unaudited | ft²												70,893
Colorado [Member] | Real Estate Dispositions [Member]
Real Estate Dispositions [Line Items]
DATE DISPOSED											Dec. 20, 2018
SALES PRICE											$ 16.9
CLOSING ADJUSTMENTS											(0.3)
NET PROCEEDS											16.6
Net Real Estate Investment											9.2
OTHER including receivables											1.4
GAIN/ (IMPAIRMENT)											$ 6
SQUARE FOOTAGE unaudited | ft²											34,068

Held for Sale - Narrative (Deta

Held for Sale - Narrative (Details)	Dec. 31, 2018property
Asset Held-for-sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties held for sale	1

Held for Sale (Details)

Held for Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Balance Sheet data (as of the period ended):
Land	$ 289,751	$ 230,206
Buildings, improvements and lease intangibles	3,986,326	3,675,415
Total real estate properties	4,359,993	3,974,071
Less accumulated depreciation	(1,121,102)	(1,015,174)
Total real estate properties, net	3,238,891	2,958,897
Assets held for sale, net	37	9,272
Liabilities of properties held for sale	145	587
Discontinued Operations [Member]
Balance Sheet data (as of the period ended):
Total real estate properties	0	19,356
Total real estate properties, net	0	8,699
Assets held for sale, net	37	9,272
Liabilities of properties held for sale	145	587
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Balance Sheet data (as of the period ended):
Land	0	1,125
Buildings, improvements and lease intangibles		18,231
Less accumulated depreciation	0	(10,657)
Other assets, net	37	573
Accounts payable and accrued liabilities	37	450
Other liabilities	$ 108	$ 137

Impairment Charges (Details)

Impairment Charges (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Impairments	$ 5.6	$ 0	$ 5.4

Other Assets (Details)

Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Straight-line rent receivables	$ 70,500	$ 69,500
Prepaid assets	44,300	66,200
Additional long-lived assets, net	22,700	23,500
Accounts Receivable, after Allowance for Credit Loss, Current	13,000	9,700
Ground lease modification, net	9,400	9,900
Equity investments in joint ventures	8,100	8,500
Debt issuance costs, net	5,000	2,200
Project costs	4,600	2,200
Goodwill	3,500	3,487
Customer relationship intangible assets, net	2,500	1,700
Above-market intangible assets, net	1,200	16,800
Interest rate swap assets		200
Other	600	800
Other Assets	$ 185,426	$ 214,697

Other Assets - Unconsolidated J

Other Assets - Unconsolidated Joint Ventures (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2017buildingLLCs	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Equity Method Investments [Roll Forward]
Net LLC investments, beginning of period		$ 8,500
Equity income (loss) recognized during the period		(19)	$ 4	$ 7
Owner distributions		(400)	(200)
Net LLC investments, end of period		8,100	8,500
Parking Garages [Member]
Property, Plant and Equipment [Line Items]
Number of LLCs | LLCs	2
Number of parking garages | building	2
Number of buildings acquired | building	3
Equity Method Investments [Roll Forward]
Net LLC investments, beginning of period		8,500	8,700
Equity income (loss) recognized during the period		0	0
Net LLC investments, end of period		$ 8,100	$ 8,500	$ 8,700

Intangible Assets and Liabili_3

Intangible Assets and Liabilities - Components of intangible assets and liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Schedule of finite lived intangible assets and liabilities
Intangible assets and liabilities, gross	$ 178.8	$ 148.3
Intangible assets and liabilities, accumulated amortization	$ 66.8	60.4
Assets and liabilities, weighted avg. life (years)	16 years 7 months 6 days
Below Market Lease Intangibles [Member] | Other Liabilities [Member]
Schedule of finite lived intangible assets and liabilities
Liabilities gross balance	$ (7.3)	(7.3)
Liabilities accumulated amortization	$ (4)	(4)
Liabilities, weighted avg. life (years)	6 years 8 months 12 days
Debt Issuance Costs [Member] | Notes and Bonds Payable [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	$ 9.2	9.3
Assets accumulated amortization	$ 3.5	2.8
Assets, weighted avg. life (years)	5 years 9 months 18 days
Goodwill [Member] | Other Assets [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	$ 3.5	3.5
Assets accumulated amortization	0	0
Debt Issuance Costs [Member] | Other Assets [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	5.8	5.4
Assets accumulated amortization	$ 0.8	3.2
Assets, weighted avg. life (years)	3 years 9 months 18 days
Above-market Lease Intangibles (Lessor) [Member] | Other Assets [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	$ 4	4.5
Assets accumulated amortization	$ 2.8	3.3
Assets, weighted avg. life (years)	3 years 10 months 24 days
Customer Relationship Intangibles (Lessor) [Member] | Other Assets [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	$ 4.1	2.7
Assets accumulated amortization	$ 1.6	$ 1
Assets, weighted avg. life (years)	43 years 1 month 6 days
Below Market Lease Intangibles [Member]
Schedule of finite lived intangible assets and liabilities
Assets, weighted avg. life (years)		3 years 9 months 18 days
At Market Lease Intangibles [Member] | Real Estate Properties [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	$ 147.9	$ 114.4
Assets accumulated amortization	$ 59.8	52
Assets, weighted avg. life (years)	5 years 4 months 24 days
Above- Market Lease Intangibles (Lessee) [Member] | Right-of-use Assets [Member]
Schedule of finite lived intangible assets and liabilities
Liabilities gross balance	$ (7.2)	(2)
Liabilities accumulated amortization	$ (0.2)	(0.1)
Liabilities, weighted avg. life (years)	75 years 6 months
Below-Market Lease Intangibles (Lessee) [Member]
Schedule of finite lived intangible assets and liabilities
Assets, weighted avg. life (years)	65 years 1 month 6 days
Below-Market Lease Intangibles (Lessee) [Member] | Right-of-use Assets [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	$ 18.8	17.8
Assets accumulated amortization	$ 2.5	$ 2.2
Assets, weighted avg. life (years)	63 years

Intangible Assets and Liabili_4

Intangible Assets and Liabilities - Expected future amortization expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible amortization expense	$ 28	$ 23.2
Future Amortization of Intangibles, Net [Abstract]
2019	24.1
2020	19.1
2021	16
2022	11.2
2023	$ 7

Notes and Bonds Payable (Detail

Notes and Bonds Payable (Details) - USD ($)	May 31, 2019	Dec. 31, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 11, 2017	Apr. 24, 2015	Feb. 28, 2014	Mar. 26, 2013
Debt Instrument [Line Items]
Notes and bonds payable		$ 1,414,069,000	$ 1,414,069,000	$ 1,345,984,000
Line of Credit [Member] | Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Notes and bonds payable		293,000,000	293,000,000	262,000,000
Medium-term Notes [Member] | Term Loan due 2022 [Member]
Debt Instrument [Line Items]
Senior and term notes face value	$ 150,000,000
Medium-term Notes [Member] | Term Loan due 2024 [Member]
Debt Instrument [Line Items]
Notes and bonds payable		199,013,000	$ 199,013,000	149,183,000
Contractual interest rates, basis spread on variable rate			1.00%
Senior and term notes face value	$ 200,000,000	200,000,000	$ 200,000,000	150,000,000			$ 200,000,000
Medium-term Notes [Member] | Term Loan due 2026 [Member]
Debt Instrument [Line Items]
Notes and bonds payable		$ 0	0
Contractual interest rates, basis spread on variable rate		1.60%
Senior Notes [Member] | Term Loan due 2026 [Member]
Debt Instrument [Line Items]
Notes and bonds payable		$ 0	0	0
Senior and term notes face value		150,000,000	150,000,000
Senior Notes [Member] | Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Notes and bonds payable		$ 248,540,000	$ 248,540,000	248,117,000
Contractual interest rates		3.75%	3.75%					3.75%
Senior and term notes face value		$ 250,000,000	$ 250,000,000	250,000,000				$ 250,000,000
Senior Notes [Member] | Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Notes and bonds payable		$ 248,522,000	$ 248,522,000	248,278,000
Contractual interest rates		3.88%	3.88%			3.875%
Senior and term notes face value		$ 250,000,000	$ 250,000,000	250,000,000		$ 250,000,000
Senior Notes [Member] | Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Notes and bonds payable		$ 295,651,000	$ 295,651,000	295,198,000
Contractual interest rates		3.63%	3.63%		3.625%
Senior and term notes face value		$ 300,000,000	$ 300,000,000	300,000,000	$ 300,000,000
Mortgage Notes [Member] | Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Notes and bonds payable		129,343,000	129,343,000	143,208,000
Senior and term notes face value		$ 129,258,000	$ 129,258,000	$ 143,115,000
LIBOR [Member] | Line of Credit [Member] | Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate			0.90%
LIBOR [Member] | Line of Credit [Member] | Term Loan due 2024 [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate			1.00%
LIBOR [Member] | Medium-term Notes [Member] | Term Loan due 2026 [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate			1.60%
Minimum [Member] | Medium-term Notes [Member] | Term Loan due 2024 [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate			0.85%
Minimum [Member] | Medium-term Notes [Member] | Term Loan due 2026 [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate	1.45%
Minimum [Member] | Mortgage Notes [Member]
Debt Instrument [Line Items]
Contractual interest rates		3.30%	3.30%
Minimum [Member] | Mortgage Notes [Member] | Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Contractual interest rates		3.31%	3.31%
Maximum [Member] | Medium-term Notes [Member] | Term Loan due 2024 [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate			1.65%
Maximum [Member] | Medium-term Notes [Member] | Term Loan due 2026 [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate	2.40%
Maximum [Member] | Mortgage Notes [Member]
Debt Instrument [Line Items]
Contractual interest rates		6.90%	6.90%
Maximum [Member] | Mortgage Notes [Member] | Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Contractual interest rates		6.88%	6.88%

Notes and Bonds Payable - Narra

Notes and Bonds Payable - Narrative (Details)	May 31, 2019USD ($)extension_option	Jul. 05, 2016USD ($)	Apr. 24, 2015USD ($)swap_agreement	Dec. 31, 2019USD ($)	Jun. 30, 2019USD ($)	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 18, 2017Lender	Dec. 11, 2017USD ($)	Feb. 28, 2014USD ($)Lender	Mar. 26, 2013USD ($)	Oct. 14, 2011USD ($)
Debt Instrument [Line Items]
Unsecured term loan outstanding				$ 1,422,258,000		$ 1,422,258,000
Notes and bonds payable				1,414,069,000		1,414,069,000	$ 1,345,984,000
Issuance costs				5,841,000		$ 5,841,000
Line of Credit [Member] | Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Unsecured credit facility													$ 700,000,000
Number of extension options | extension_option	2
Period of extension option	6 months
Extension fees as percentage of aggregate commitments	0.0625%
Facility fee on the aggregate amount of commitments						0.20%
Amount outstanding under Unsecured Credit Facility				$ 293,000,000		$ 293,000,000
Weighted average interest rate (LOC)				2.66%		2.66%
Remaining borrowing capacity				$ 407,000,000		$ 407,000,000
Notes and bonds payable				$ 293,000,000		$ 293,000,000	262,000,000
Line of Credit [Member] | Unsecured Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Facility fee on the aggregate amount of commitments						0.125%
Line of Credit [Member] | Unsecured Credit Facility [Member] | Maximum [Member]
Debt Instrument [Line Items]
Facility fee on the aggregate amount of commitments						0.30%
Line of Credit [Member] | Unsecured Credit Facility [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Percentage of interest in addition to LIBOR						0.90%
Contractual interest rates, basis spread on variable rate						0.90%
Line of Credit [Member] | Unsecured Credit Facility [Member] | LIBOR [Member] | Minimum [Member]
Debt Instrument [Line Items]
Percentage of interest in addition to LIBOR						0.775%
Line of Credit [Member] | Unsecured Credit Facility [Member] | LIBOR [Member] | Maximum [Member]
Debt Instrument [Line Items]
Percentage of interest in addition to LIBOR						1.45%
Line of Credit [Member] | Term Loan due 2024 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate						1.00%
Medium-term Notes [Member] | Term Loan due 2024 [Member]
Debt Instrument [Line Items]
Weighted average interest rate (LOC)				2.29%		2.29%
Senior notes face value	$ 200,000,000			$ 200,000,000		$ 200,000,000	150,000,000				$ 200,000,000
Number of lenders, term loan | Lender									9		9
Amount of debt repaid		$ 50,000,000
Contractual interest rates, basis spread on variable rate						1.00%
Unsecured term loan outstanding				$ 200,000,000		$ 200,000,000
Interest rate yielded per annum upon issuance				3.27%		3.27%
Amortization of debt issuance costs					$ 300,000	$ 200,000	200,000	$ 200,000
Notes and bonds payable				$ 199,013,000		199,013,000	149,183,000
Deferred finance costs, gross	700,000
Issuance costs	400,000			987,000		987,000	817,000
Medium-term Notes [Member] | Term Loan due 2024 [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative notional amount				$ 175,000,000		$ 175,000,000
Medium-term Notes [Member] | Term Loan due 2024 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate						0.85%
Medium-term Notes [Member] | Term Loan due 2024 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate						1.65%
Medium-term Notes [Member] | Term Loan due 2022 [Member]
Debt Instrument [Line Items]
Senior notes face value	$ 150,000,000
Medium-term Notes [Member] | Term Loan due 2026 [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate				1.60%
Amortization of debt issuance costs					$ 400,000
Delayed draw feature period	9 months
Anticipated amount of investment	$ 150,000,000
Notes and bonds payable				$ 0		$ 0
Ticking fee				0.20%
Deferred finance costs, gross	1,100,000
Issuance costs	$ 700,000
Medium-term Notes [Member] | Term Loan due 2026 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate	1.45%
Ticking fee	0.125%
Medium-term Notes [Member] | Term Loan due 2026 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate	2.40%
Ticking fee	0.30%
Medium-term Notes [Member] | Term Loan due 2026 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate						1.60%
Senior Notes [Member] | Term Loan due 2026 [Member]
Debt Instrument [Line Items]
Senior notes face value				$ 150,000,000		$ 150,000,000
Notes and bonds payable				0		0	0
Senior Notes [Member] | Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Senior notes face value				250,000,000		250,000,000	250,000,000					$ 250,000,000
Interest rate yielded per annum upon issuance												3.95%
Amortization of debt issuance costs						200,000	200,000	200,000
Notes and bonds payable				248,540,000		248,540,000	248,117,000
Deferred finance costs, gross												$ 2,100,000
Issuance costs				$ 699,000		$ 699,000	909,000
Interest rate on senior notes				3.75%		3.75%						3.75%
Unaccreted discount				$ 761,000		$ 761,000	974,000					$ 2,100,000
Amount of amortization included in interest expense on the Company's consolidated Statements of operations						200,000	200,000	200,000
Senior Notes [Member] | Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Senior notes face value			$ 250,000,000	250,000,000		250,000,000	250,000,000
Interest rate yielded per annum upon issuance			4.08%
Amortization of debt issuance costs						200,000	200,000	200,000
Notes and bonds payable				248,522,000		248,522,000	248,278,000
Deferred finance costs, gross			$ 2,300,000
Issuance costs				$ 1,357,000		$ 1,357,000	1,581,000
Interest rate on senior notes			3.875%	3.88%		3.88%
Unaccreted discount			$ 200,000	$ 121,000		$ 121,000	141,000
Number of forward starting swaps | swap_agreement			4
Senior Notes [Member] | Senior Notes due 2025 [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Settlement of swap agreements			$ 1,700,000
Senior Notes [Member] | Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Senior notes face value				300,000,000		300,000,000	300,000,000			$ 300,000,000
Interest rate yielded per annum upon issuance										3.84%
Amortization of debt issuance costs						200,000
Notes and bonds payable				295,651,000		295,651,000	295,198,000
Deferred finance costs, gross										$ 2,700,000
Issuance costs				$ 2,249,000		$ 2,249,000	2,483,000
Interest rate on senior notes				3.63%		3.63%				3.625%
Unaccreted discount				$ 2,100,000		$ 2,100,000	2,319,000			$ 2,500,000
Amount of amortization included in interest expense on the Company's consolidated Statements of operations						200,000
Mortgage Notes [Member]
Debt Instrument [Line Items]
Issuance costs				$ 500,000		$ 500,000
Mortgage Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate on senior notes				3.30%		3.30%
Mortgage Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate on senior notes				6.90%		6.90%
Mortgage Notes [Member] | Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Senior notes face value				$ 129,258,000		$ 129,258,000	143,115,000
Amortization of debt issuance costs						200,000	100,000
Notes and bonds payable				129,343,000		129,343,000	143,208,000
Issuance costs				549,000		549,000	744,000
Unaccreted discount				$ 528,000		528,000	968,000
Amortization of debt discount						600,000	400,000	300,000
Amortization of debt premium						$ 400,000	$ 800,000	$ 700,000
Mortgage Notes [Member] | Mortgage Notes Payable [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate on senior notes				3.31%		3.31%
Mortgage Notes [Member] | Mortgage Notes Payable [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate on senior notes				6.88%		6.88%
Up-front Payment Arrangement [Member] | Line of Credit [Member] | Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Fee amount				$ 3,500,000		$ 3,500,000

Notes and Bonds Payable - Senio

Notes and Bonds Payable - Senior and Term Notes (Details) - USD ($)	Dec. 31, 2019	May 31, 2019	Dec. 31, 2018	Dec. 11, 2017	Apr. 24, 2015	Feb. 28, 2014	Mar. 26, 2013
Debt Instrument [Line Items]
Debt issuance costs	$ (5,841,000)
Notes and bonds payable	$ 1,414,069,000		$ 1,345,984,000
Medium-term Notes [Member] | Term Loan due 2024 [Member]
Debt Instrument [Line Items]
Effective Interest rate	3.27%
Senior and term notes face value	$ 200,000,000	$ 200,000,000	150,000,000			$ 200,000,000
Debt issuance costs	(987,000)	(400,000)	(817,000)
Notes and bonds payable	199,013,000		149,183,000
Medium-term Notes [Member] | Term Loan due 2022 [Member]
Debt Instrument [Line Items]
Senior and term notes face value		$ 150,000,000
Senior Notes [Member] | Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Effective Interest rate							3.95%
Senior and term notes face value	250,000,000		250,000,000				$ 250,000,000
Unaccreted discount	(761,000)		(974,000)				$ (2,100,000)
Debt issuance costs	(699,000)		(909,000)
Notes and bonds payable	248,540,000		248,117,000
Senior Notes [Member] | Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Effective Interest rate					4.08%
Senior and term notes face value	250,000,000		250,000,000		$ 250,000,000
Unaccreted discount	(121,000)		(141,000)		$ (200,000)
Debt issuance costs	(1,357,000)		(1,581,000)
Notes and bonds payable	248,522,000		248,278,000
Senior Notes [Member] | Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Effective Interest rate				3.84%
Senior and term notes face value	300,000,000		300,000,000	$ 300,000,000
Unaccreted discount	(2,100,000)		(2,319,000)	$ (2,500,000)
Debt issuance costs	(2,249,000)		(2,483,000)
Notes and bonds payable	$ 295,651,000		$ 295,198,000

Notes and Bonds Payable - Mortg

Notes and Bonds Payable - Mortgage Notes (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Debt Instrument [Line Items]
Issuance costs	$ (5,841)
Notes and bonds payable	1,414,069	$ 1,345,984
Mortgage Notes [Member]
Debt Instrument [Line Items]
Issuance costs	(500)
Mortgage Notes Payable [Member] | Mortgage Notes [Member]
Debt Instrument [Line Items]
Mortgage notes	129,258	143,115
Unamortized premium	1,162	1,805
Unaccreted discount	(528)	(968)
Issuance costs	(549)	(744)
Notes and bonds payable	$ 129,343	$ 143,208

Notes and Bonds Payable - Detai

Notes and Bonds Payable - Details of Mortgage Notes (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019USD ($)mortgage_loanmortgage_note_payable	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Number of outstanding mortgage notes | mortgage_loan	16
Mortgage Notes [Member]
Debt Instrument [Line Items]
Investment in Collateral	$ 369.6
Mortgage notes payable carrying amount	$ 129.3	$ 143.2
Number of outstanding mortgage notes | mortgage_note_payable	17
Mortgage Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Contractual interest rates	3.30%
Mortgage Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Contractual interest rates	6.90%
Mortgage Notes [Member] | Mortgage Notes 4.55% [Member] | Commercial Bank [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 9.4
Effective Interest rate	4.55%
Maturity Date	2019-07
Collateral	MOB
Principal and Interest Payments	Monthly/8-yr amort
Principal and interest amortization period	8 years
Investment in Collateral	$ 0
Mortgage notes payable carrying amount	0	9
Unencumbered gross investment	27.8
Mortgage Notes [Member] | Mortgage Notes 7.65% [Member] | Commercial Bank [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 15.2
Effective Interest rate	7.65%
Maturity Date	2020-07
Collateral	MOB
Principal and interest amortization period	11 years
Investment in Collateral	$ 18.6
Mortgage notes payable carrying amount	12.5	12.5
Unaccreted discount	$ 2.4
Period for monthly installments of interest	24 months
Mortgage Notes [Member] | Mortgage Notes 4.00% [Member] | Life Insurance Co. [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 7.9
Effective Interest rate	4.00%
Maturity Date	2020-08
Collateral	MOB
Principal and Interest Payments	Monthly/15-yr amort.
Principal and interest amortization period	15 years
Investment in Collateral	$ 20.7
Mortgage notes payable carrying amount	0.5	1.3
Unamortized premium	0.3
Mortgage Notes [Member] | Mortgage Notes 5.25% [Member] | Life Insurance Co. [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 7.3
Effective Interest rate	5.25%
Maturity Date	2020-08
Collateral	MOB
Principal and Interest Payments	Monthly/27-yr amort.
Principal and interest amortization period	27 years
Investment in Collateral	$ 18.1
Mortgage notes payable carrying amount	6	6.2
Unamortized premium	0.4
Mortgage Notes [Member] | Mortgage Notes 4.30% [Member] | Life Insurance Co. [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 5.6
Effective Interest rate	4.30%
Maturity Date	2021-01
Collateral	MOB
Principal and Interest Payments	Monthly/10-yr amort.
Principal and interest amortization period	10 years
Investment in Collateral	$ 15.8
Mortgage notes payable carrying amount	4.5	4.6
Unamortized premium	0.2
Mortgage Notes [Member] | Mortgage Notes 6.43% [Member] | Commercial Bank [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 12.9
Effective Interest rate	6.43%
Maturity Date	2021-02
Collateral	MOB
Principal and Interest Payments	Monthly/12-yr amort.
Principal and interest amortization period	12 years
Investment in Collateral	$ 55.2
Mortgage notes payable carrying amount	10.1	10.3
Unaccreted discount	1
Mortgage Notes [Member] | Mortgage Notes 3.87% [Member] | Life Insurance Co. [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 11
Effective Interest rate	3.87%
Maturity Date	2022-11
Collateral	MOB
Principal and Interest Payments	Monthly/7-yr amort.
Principal and interest amortization period	7 years
Investment in Collateral	$ 22
Mortgage notes payable carrying amount	10	10.2
Unaccreted discount	0.1
Mortgage Notes [Member] | Mortgage Notes 3.86% [Member] | Life Insurance Co. [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 12.3
Effective Interest rate	3.86%
Maturity Date	2023-08
Collateral	MOB
Principal and Interest Payments	Monthly/7-yr amort.
Principal and interest amortization period	7 years
Investment in Collateral	$ 25.4
Mortgage notes payable carrying amount	10.9	11.2
Unaccreted discount	0.2
Mortgage Notes [Member] | Mortgage Notes 4.27% [Member] | Financial Services [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 12.4
Effective Interest rate	4.27%
Maturity Date	2023-10
Collateral	MOB
Principal and Interest Payments	Monthly/10-yr amort.
Principal and interest amortization period	10 years
Investment in Collateral	$ 22.6
Mortgage notes payable carrying amount	11.7	12
Unamortized premium	0.4
Mortgage Notes [Member] | Mortgage Notes 4.84% [Member] | Life Insurance Co. [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 9
Effective Interest rate	4.84%
Maturity Date	2023-12
Collateral	MOB,OFC
Principal and Interest Payments	Monthly/10-yr amort.
Principal and interest amortization period	10 years
Investment in Collateral	$ 25.7
Mortgage notes payable carrying amount	7.6	7.8
Unamortized premium	0.1
Mortgage Notes [Member] | Mortgage Notes 4.13% [Member] | Life Insurance Co. [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 13.3
Effective Interest rate	4.13%
Maturity Date	2024-01
Collateral	MOB
Principal and Interest Payments	Monthly/10-yr amort.
Principal and interest amortization period	10 years
Investment in Collateral	$ 20.8
Mortgage notes payable carrying amount	12.7	13
Unamortized premium	0.8
Mortgage Notes [Member] | Mortgage Notes 3.96% [Member] | Life Insurance Co. [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 6.8
Effective Interest rate	3.96%
Maturity Date	2024-02
Collateral	MOB
Principal and Interest Payments	Monthly/7-yr amort.
Principal and interest amortization period	7 years
Investment in Collateral	$ 14.6
Mortgage notes payable carrying amount	6.4	6.6
Unamortized premium	0.2
Mortgage Notes [Member] | Mortgage Notes 4.32% [Member] | Financial Services [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 9.7
Effective Interest rate	4.32%
Maturity Date	2024-09
Collateral	MOB
Principal and Interest Payments	Monthly/10-yr amort.
Principal and interest amortization period	10 years
Investment in Collateral	$ 17
Mortgage notes payable carrying amount	8.3	8.6
Unamortized premium	0.1
Mortgage Notes [Member] | Mortgage Notes 3.71% [Member] | Commercial Bank [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 11.5
Effective Interest rate	3.71%
Maturity Date	2026-01
Collateral	MOB
Principal and Interest Payments	Monthly/10-yr amort.
Principal and interest amortization period	10 years
Investment in Collateral	$ 38.6
Mortgage notes payable carrying amount	9.6	10.1
Mortgage Notes [Member] | Mortgage Notes 5.25% 20 Year [Member] | Commercial Bank [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 15
Effective Interest rate	5.25%
Maturity Date	2027-04
Collateral	MOB
Principal and Interest Payments	Monthly/20-yr amort.
Principal and interest amortization period	20 years
Investment in Collateral	$ 33.5
Mortgage notes payable carrying amount	7.9	8.8
Unamortized premium	0.7
Mortgage Notes [Member] | Mortgage Notes 4.79% [Member] | Municipal Government [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 11
Effective Interest rate	4.79%
Collateral	MOB
Investment in Collateral	$ 21
Mortgage notes payable carrying amount	10.6	$ 11
Unamortized premium	$ 1
Number of outstanding mortgage notes | mortgage_note_payable	3

Notes and Bonds Payable - Futur

Notes and Bonds Payable - Future Maturities (Details) $ in Thousands	Dec. 31, 2019USD ($)mortgage_loan	Dec. 31, 2018USD ($)
Long Term Debt Maturities [Line Items]
Number of outstanding mortgage notes | mortgage_loan	16
Excluded debt issuance costs	$ 5,000
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	1,422,258
Net Accretion/Amortization	(2,348)
Debt issuance costs	(5,841)
Notes and bonds payable	$ 1,414,069	$ 1,345,984
%	100.00%
2020 [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 23,064
Net Accretion/Amortization	(392)
Debt issuance costs	(1,081)
Notes and bonds payable	$ 21,591
%	1.50%
2021 [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 17,594
Net Accretion/Amortization	(326)
Debt issuance costs	(1,065)
Notes and bonds payable	$ 16,203
%	1.10%
2022 [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 12,977
Net Accretion/Amortization	(336)
Debt issuance costs	(1,077)
Notes and bonds payable	$ 11,564
%	0.80%
2023 [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 573,230
Net Accretion/Amortization	(183)
Debt issuance costs	(921)
Notes and bonds payable	$ 572,126
%	40.50%
2024 [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 225,966
Net Accretion/Amortization	(262)
Debt issuance costs	(667)
Notes and bonds payable	$ 225,037
%	15.90%
2025 and thereafter [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 569,427
Net Accretion/Amortization	(849)
Debt issuance costs	(1,030)
Notes and bonds payable	$ 567,548
%	40.20%

Derivative Financial Instrume_3

Derivative Financial Instruments (Details) $ in Millions	Dec. 31, 2019USD ($)swap_agreementderivative
Derivative [Line Items]
Number of interest rate derivatives | derivative	8
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest Rate Swap - 2017 [Member]
Derivative [Line Items]
Number of interest rate derivatives | swap_agreement	2
Derivative notional amount | $	$ 25
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest Rate Swap - 2018 [Member]
Derivative [Line Items]
Number of interest rate derivatives | swap_agreement	2
Derivative notional amount | $	$ 50
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Interest Rate Swap - 2019 [Member]
Derivative [Line Items]
Number of interest rate derivatives | swap_agreement	4
Derivative notional amount | $	$ 100
Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Forward Starting Interest Rate Swap [Member]
Derivative [Line Items]
Number of interest rate derivatives | swap_agreement	8
Derivative notional amount | $	$ 175

Derivative Financial Instrume_4

Derivative Financial Instruments - Fair Value of Derivative Instruments on the Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities	$ (5,280)
Interest Rate Swap - 2017 [Member] | Designated as Hedging Instrument [Member] | Other Assets [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities		$ 229
Interest Rate Swap - 2017 [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
GROSS AMOUNTS of recognized assets	(467)
Interest Rate Swap - 2018 [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities	(1,335)	(68)
Interest Rate Swap - 2019 [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities	(3,478)	0
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
GROSS AMOUNTS of recognized assets	$ (5,280)
Gross Amounts of Recognized Liabilities		$ 161

Derivative Financial Instrume_5

Derivative Financial Instruments - Effect of Cash Flow Hedging on AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Derivative [Line Items]
AMOUNT OF (LOSS) RECOGNIZED IN OCI on derivatives	$ (5,592)
AMOUNT OF (GAIN)/LOSS RECLASSIFIED FROM OCI INTO INCOME for the twelve months ended December 31,	(319)	$ (424)	$ (176)
Interest Rate Swap - 2017 [Member]
Derivative [Line Items]
AMOUNT OF (LOSS) RECOGNIZED IN OCI on derivatives	(674)
Interest Rate Swap - 2018 [Member]
Derivative [Line Items]
AMOUNT OF (LOSS) RECOGNIZED IN OCI on derivatives	(1,366)
Interest Rate Swap - 2019 [Member]
Derivative [Line Items]
AMOUNT OF (LOSS) RECOGNIZED IN OCI on derivatives	(3,552)
Interest Rate Swap [Member]
Derivative [Line Items]
AMOUNT OF (LOSS) RECOGNIZED IN OCI on derivatives	0
Interest Expense [Member]
Derivative [Line Items]
AMOUNT OF (GAIN)/LOSS RECLASSIFIED FROM OCI INTO INCOME for the twelve months ended December 31,	319	424
Interest Expense [Member] | Interest Rate Swap - 2017 [Member]
Derivative [Line Items]
AMOUNT OF (GAIN)/LOSS RECLASSIFIED FROM OCI INTO INCOME for the twelve months ended December 31,	(22)	51
Interest Expense [Member] | Interest Rate Swap - 2018 [Member]
Derivative [Line Items]
AMOUNT OF (GAIN)/LOSS RECLASSIFIED FROM OCI INTO INCOME for the twelve months ended December 31,	99	204
Interest Expense [Member] | Interest Rate Swap - 2019 [Member]
Derivative [Line Items]
AMOUNT OF (GAIN)/LOSS RECLASSIFIED FROM OCI INTO INCOME for the twelve months ended December 31,	74	0
Interest Expense [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
AMOUNT OF (GAIN)/LOSS RECLASSIFIED FROM OCI INTO INCOME for the twelve months ended December 31,	$ 168	$ 169

Derivative Financial Instrume_6

Derivative Financial Instruments - Offsetting Derivatives (Details) $ in Thousands	Dec. 31, 2019USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
GROSS AMOUNTS of recognized liabilities	$ (5,280)
GROSS AMOUNTS OFFSET in the Consolidated Balance Sheets	0
NET AMOUNTS OF LIABILITIES presented in the Consolidated Balance Sheets	(5,280)
FINANCIAL INSTRUMENTS	5,280
CASH COLLATERAL	0
NET AMOUNT	$ 0

Derivative Financial Instrume_7

Derivative Financial Instruments - Narrative (Details) $ in Millions	Dec. 31, 2019USD ($)derivative
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Number of interest rate derivatives | derivative	8
Reclassified from accumulated other comprehensive loss	$ 1.4
Fair value of derivatives in a net liability position	5.5
Assets needed if immediate settlement is required, aggregate fair value	$ 5.5

Stockholders' Equity - Common s

Stockholders' Equity - Common shares (Details) - shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of the beginning and ending common stock outstanding
Balance, beginning of year (shares)	125,279,000
Balance, end of year (shares)	134,706,000	125,279,000
Common Stock [Member]
Reconciliation of the beginning and ending common stock outstanding
Balance, beginning of year (shares)	125,279,455	125,131,593	116,416,900
Issuance of common stock (shares)	9,251,440	26,203	8,395,607
Non-vested stock-based awards, net of withheld shares and forfeitures (shares)	175,259	121,659	319,086
Balance, end of year (shares)	134,706,154	125,279,455	125,131,593

Stockholders' Equity - Equity O

Stockholders' Equity - Equity Offering Programs (Details) - USD ($) $ / shares in Units, $ in Thousands	Mar. 19, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 31, 2020
Class of Stock [Line Items]
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01
Net proceeds		$ 295,946	$ 611	$ 248,554
At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Issuance of common stock (shares)		5,470,673	0	0
Net proceeds		$ 179,100	$ 0	$ 0
Minimum [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Shares issued during period (in dollars per share)		$ 32.01
Maximum [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Shares issued during period (in dollars per share)		$ 33.77
Subsequent Event [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Number of authorized shares remaining under offering program (shares)					398,024
Equity Offering [Member]
Class of Stock [Line Items]
Issuance of common stock (shares)	3,737,500
Common stock, par value (in dollars per share)	$ 0.01
Net proceeds	$ 115,800
Shares issued in equity offering (in dollars per share)	$ 31.40

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details) - USD ($)	Feb. 11, 2020	Apr. 30, 2019	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Repurchased of common stock		$ 50,000,000
Dividend Declared [Member]
Class of Stock [Line Items]
Dividends per share to common stockholders, declared (in USD per share)			$ 0.3	$ 0.3	$ 0.3	$ 0.3	$ 1.20
Dividend Declared [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Dividends per share to common stockholders, declared (in USD per share)	$ 0.30

Stockholders' Equity - Accumula

Stockholders' Equity - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Period of impact on net income	10 years
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income	$ (5,273)	$ 397	$ 102
Forward Starting Swaps [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	(902)	(1,299)
Other comprehensive loss before reclassifications	319	424
Amounts reclassified from accumulated other comprehensive income (loss)	(5,592)	(27)
Other comprehensive income	(5,273)	397
Balance, end of period	$ (6,175)	$ (902)	$ (1,299)

Stockholders' Equity - Reclassi

Stockholders' Equity - Reclassifications out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense	$ 55,435	$ 52,804	$ 56,402
Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Amounts reclassified from accumulated other comprehensive income (loss)	319
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) Related to Settled Interest Rate Swaps [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense	168
Amounts Reclassified from Accumulated Other Comprehensive Income (Loss) Related to Current Interest Rate Swaps [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense	$ 151

Stock and Other Incentive Pla_3

Stock and Other Incentive Plans - Narrative (Details)

Dec. 12, 2019USD ($)executive_officershares

Sep. 30, 2019USD ($)shares

Dec. 12, 2018USD ($)shares

Dec. 11, 2017USD ($)executive_officershares

Dec. 30, 2016USD ($)shares

Dec. 16, 2016

Mar. 01, 2016USD ($)shares

Feb. 16, 2016

Jul. 31, 2012

Mar. 31, 2019USD ($)executive_officershares

Dec. 31, 2018shares

Mar. 31, 2018USD ($)executive_officershares

Dec. 31, 2024USD ($)

Dec. 31, 2023USD ($)

Dec. 31, 2022USD ($)

Dec. 31, 2021USD ($)

Dec. 31, 2020USD ($)

Dec. 31, 2019USD ($)shares

Dec. 31, 2018USD ($)shares

Dec. 31, 2017USD ($)executive_officershares

Dec. 31, 2016Awards

Dec. 31, 2015shares

Dec. 31, 2014

401(k) Plan [Abstract]

Percentage of matching contribution

3.00%

Value of matching contribution

$ 500,000

$ 400,000

$ 400,000

Former Executive Chairman [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 2,900,000

Withheld of common stock (shares) | shares

80,490

Employee Stock Purchase Plan [Member]

401(k) Plan [Abstract]

Value of shares available for grant each year

$ 25,000

Discount on market price on the date of grant

85.00%

Discount on market price on the date of exercise

85.00%

Option expiration period

27 months

Cash received from employees upon exercising options

$ 1,000,000

$ 400,000

$ 800,000

Deferral Option One [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Salary Deferral Plan employer matching contribution, percent

30.00%

Deferral Option Two [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Salary Deferral Plan employer matching contribution, percent

50.00%

Deferral Option Three [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Salary Deferral Plan employer matching contribution, percent

100.00%

2015 Incentive Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Authorization of common shares to issue (shares) | shares

3,500,000

Common shares issued, net of forfeitures (shares) | shares

1,988,079

1,711,240

Number of shares authorized (shares) | shares

1,788,760

1,511,921

1,788,760

2015 Incentive Plan [Member] | Restricted Stock [Member] | Minimum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

3 years

2015 Incentive Plan [Member] | Restricted Stock [Member] | Maximum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

8 years

Stock Incentive Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Common shares issued, net of forfeitures (shares) | shares

1,878,637

Granted in period (in shares) | shares

276,839

273,012

413,489

Stock Incentive Plan [Member] | Executive Officer [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 3,500,000

$ 1,700,000

$ 1,700,000

Number of one-time non-vested share grants | Awards

3

Stock Incentive Plan [Member] | Director [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 800,000

Award vesting period

1 year

3 years

Shares issued under the plan (shares) | shares

24,996

30,989

23,231

Stock Incentive Plan [Member] | Chief Financial Officer [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 200,000

Award vesting period

10 years

Granted in period (in shares) | shares

50,000

Stock Incentive Plan [Member] | President and Chief Executive Officer [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 600,000

Award vesting period

10 years

Granted in period (in shares) | shares

200,000

Stock Incentive Plan [Member] | Executive Chairman [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 2,000,000

$ 900,000

Award vesting period

5 years

Granted in period (in shares) | shares

150,000

Stock Incentive Plan [Member] | Restricted Stock [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 12,000,000

$ 10,400,000

$ 9,800,000

Withheld of common stock (shares) | shares

101,580

151,353

94,403

Stock Incentive Plan [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Value of performance based awards released

$ 1,000,000

$ 1,200,000

Shares issued under the plan (shares) | shares

31,262

43,414

Stock Incentive Plan [Member] | Performance Shares [Member] | Executive Officer [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of executive officers granted awards | executive_officer

4

4

Stock Incentive Plan [Member] | Performance Shares [Member] | Senior Vice President [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of executive officers granted awards | executive_officer

5

5

Stock Incentive Plan [Member] | Performance Shares [Member] | Officer [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 1,100,000

$ 1,200,000

$ 1,100,000

Stock Incentive Plan [Member] | Performance Shares [Member] | Minimum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

3 years

Stock Incentive Plan [Member] | Performance Shares [Member] | Maximum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

8 years

Stock Incentive Plan [Member] | Performance Shares [Member] | Weighted Average [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

6 years

Stock Incentive Plan [Member] | Restricted Stock and Performance Based Awards [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Weighted average amortization period remaining

5 years

Stock Incentive Plan [Member] | Restricted Stock and Performance Based Awards [Member] | Minimum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

1 year

Stock Incentive Plan [Member] | Restricted Stock and Performance Based Awards [Member] | Maximum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

8 years

Executive Incentive Plan [Member] | Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 5,700,000

5,700,000

$ 5,000,000

Executive Incentive Plan [Member] | Performance Shares [Member] | Minimum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shareholder return performance period used to measure award

1 year

Executive Incentive Plan [Member] | Performance Shares [Member] | Maximum [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Shareholder return performance period used to measure award

3 years

Executive Incentive Plan [Member] | 2019 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

5 years

Granted in period

$ 6,100,000

Granted in period (in shares) | shares

187,072

Executive Incentive Plan [Member] | 2019 Performance Shares [Member] | Executive Officer [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of executive officers granted awards | executive_officer

4

Executive Incentive Plan [Member] | 2019 Performance Shares [Member] | Senior Vice President [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of executive officers granted awards | executive_officer

5

Executive Incentive Plan [Member] | 2019 Performance Shares [Member] | First Vice President [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of executive officers granted awards | executive_officer

5

Executive Incentive Plan [Member] | 2018 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

1,000,000

Award vesting period

5 years

Granted in period

$ 5,000,000

Granted in period (in shares) | shares

165,261

Executive Incentive Plan [Member] | 2018 Performance Shares [Member] | First Vice President [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of executive officers granted awards | executive_officer

5

Executive Incentive Plan [Member] | 2017 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

2,000,000

Award vesting period

5 years

Granted in period

$ 10,100,000

Granted in period (in shares) | shares

309,874

Executive Incentive Plan [Member] | 2017 Performance Shares [Member] | Executive Officer [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of executive officers granted awards | executive_officer

5

Executive Incentive Plan [Member] | 2017 Performance Shares [Member] | First Vice President [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of executive officers granted awards | executive_officer

4

Executive Incentive Plan [Member] | 2016 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

5 years

Executive Incentive Plan [Member] | 3-year Vesting [Member] | February 2016 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

3 years

Executive Incentive Plan [Member] | 5-year Vesting [Member] | February 2016 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

5 years

Executive Incentive Plan [Member] | Forecast [Member] | 2019 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 1,100,000

$ 1,200,000

$ 1,200,000

$ 1,200,000

$ 1,200,000

Executive Incentive Plan [Member] | Forecast [Member] | 2018 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 900,000

1,000,000

1,000,000

1,000,000

Executive Incentive Plan [Member] | Forecast [Member] | 2017 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 1,900,000

$ 2,000,000

2,000,000

Executive Incentive Plan [Member] | Forecast [Member] | 2016 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

1,300,000

Executive Incentive Plan [Member] | Forecast [Member] | February 2016 Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 700,000

Salary Deferral Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 900,000

$ 1,000,000

$ 1,200,000

Shares issued under the plan (shares) | shares

33,509

33,348

39,016

Maximum salary deferral for officers under the plan, percent

50.00%

Salary Deferral Plan [Member] | Deferral Option One [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

3 years

Salary Deferral Plan [Member] | Deferral Option Two [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

5 years

Salary Deferral Plan [Member] | Deferral Option Three [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Award vesting period

8 years

Dividend Reinvestment Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Authorization of common shares to issue (shares) | shares

1,000,000

401(k) Plan [Abstract]

Total DRIP shares issued under the Plan (shares) | shares

599,104

Total shares issued under the Dividend Reinvestment Plan (shares) | shares

7,990

9,487

26,031

General and Administrative Expense [Member] | Employee Stock Purchase Plan [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Accelerated stock compensation expense

$ 200,000

$ 300,000

$ 200,000

Stock and Other Incentive Pla_4

Stock and Other Incentive Plans - Amortization of Compensation for Nonvested Shares (Details) $ in Millions	Dec. 31, 2019USD ($)
Share-based Payment Arrangement [Abstract]
2020	$ 8.7
2021	7.3
2022	5.9
2023	3.8
2024	2.5
2025 and thereafter	1.9
Total	$ 30.1

Stock and Other Incentive Pla_5

Stock and Other Incentive Plans - 2015 Incentive Plan and related information (Details) - Stock Incentive Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of the activity under the incentive plans
Share-based awards, beginning of year (shares)	1,769,863	1,907,645	1,786,497
Granted (shares)	276,839	273,012	413,489
Vested (shares)	(292,636)	(410,794)	(292,341)
Share-based awards, end of year (shares)	1,754,066	1,769,863	1,907,645
Weighted-average grant date fair value of:
Share-based awards, beginning of year (in USD per share)	$ 29.36	$ 28.44	$ 27.18
Share-based awards granted during the year (in USD per share)	31.75	29.72	32.05
Share-based awards vested during the year (in USD per share)	28.84	25.32	25.88
Share-based awards, end of year (in USD per share)	$ 29.82	$ 29.36	$ 28.44
Grant date fair value of shares granted during the year	$ 8,791	$ 8,114	$ 13,254

Stock and Other Incentive Pla_6

Stock and Other Incentive Plans - Employee Stock Purchase Plan (Details) - Employee Stock Purchase Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock Options Outstanding:
Options outstanding, beginning of year (shares)	328,533	318,100	316,321
Granted (shares)	235,572	203,836	206,824
Exercised (shares)	(35,277)	(16,716)	(32,076)
Forfeited (shares)	(54,095)	(40,897)	(40,659)
Expired (shares)	(142,074)	(135,790)	(132,310)
Outstanding, end of period (shares)	332,659	328,533	318,100
Weighted-average exercise price:
Options outstanding, beginning of year (in USD per share)	$ 24.17	$ 25	$ 23.69
Options granted during the year (in USD per share)	24.17	27.30	25.77
Options exercised during the year (in USD per share)	25.01	24.01	24.31
Options forfeited during the year (in USD per share)	25.26	24.06	25.01
Options expired during the year (in USD per share)	25.77	23.55	23.22
Options outstanding, end of year (in USD per share)	25.59	24.17	25
Weighted-average fair value of options granted during the year (calculated as of the grant date) (in USD per share)	$ 7.02	$ 7.81	$ 6.31
Intrinsic value of options exercised during the year	$ 269	$ 71	$ 271
Intrinsic value of options outstanding (calculated as of December 31)	$ 2,589	$ 1,402	$ 2,683
Exercise prices of options outstanding (calculated as of December 31) (in USD per share)	$ 25.59	$ 24.17	$ 25
Weighted-average contractual life of outstanding options (calculated as of December 31, in years)	24 days	24 days	24 days

Stock and Other Incentive Pla_7

Stock and Other Incentive Plans - Black-Scholes Options Pricing Model (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair value of options issued based on weighted-average assumptions
Risk-free interest rates	2.48%	1.89%	1.20%
Expected dividend yields	4.19%	3.66%	3.70%
Expected life (in years)	1 year 5 months 12 days	1 year 5 months 12 days	1 year 5 months 12 days
Expected volatility	29.80%	28.40%	20.40%
Expected forfeiture rates	85.00%	85.00%	85.00%

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Weighted Average Common Shares
Weighted average Common Shares outstanding (in shares)									129,735,723	125,219,773	119,739,216
Non-vested shares (in shares)									(1,736,022)	(1,927,648)	(1,813,058)
Weighted average Common Shares - Basic (in shares)									127,999,701	123,292,125	117,926,158
Dilutive effect of employee stock purchase plan (in shares)									84,283	58,808	91,007
Weighted average Common Shares - Diluted (in shares)									128,083,984	123,350,933	118,017,165
Net income									$ 39,185	$ 69,771	$ 23,092
Dividends paid on nonvested share-based awards									(2,075)	(2,320)
Dividends paid on nonvested share-based awards											(2,149)
Net income applicable to common stockholders									$ 37,110	$ 67,451	$ 20,943
Basic earnings per common share (in USD per share)	$ 0.20	$ 0.02	$ 0.03	$ 0.04	$ 0.13	$ 0.05	$ 0.30	$ 0.07	$ 0.29	$ 0.55	$ 0.18
Diluted earnings per common share (in USD per share)	$ 0.20	$ 0.02	$ 0.03	$ 0.04	$ 0.13	$ 0.05	$ 0.30	$ 0.07	$ 0.29	$ 0.55	$ 0.18

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)ft²land_parcel	Dec. 31, 2018USD ($)
Property, Plant and Equipment [Line Items]
Approximate square feet | ft²	15,400,000
Number of land parcels held for development | land_parcel	7
Investment in land held for development	$ 24,600	$ 24,600
First and Second Generation Leases [Member] | Tenant Improvement Allowances [Member]
Property, Plant and Equipment [Line Items]
Anticipated amount of investment	$ 46,600
Medical Office Building Expansion [Member] | North Carolina [Member]
Property, Plant and Equipment [Line Items]
Approximate square feet | ft²	40,278
Medical Office Building [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	$ 34,243
Approximate square feet | ft²	261,883
Medical Office Building [Member] | North Carolina [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	$ 1,500
Medical Office Building [Member] | Memphis, Tennessee [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	$ 9,032
Approximate square feet | ft²	110,883
Total funding during the year, excluding purchase of land and building	$ 300
Medical Office Building [Member] | Memphis, Tennessee [Member] | Land and Building [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	8,700
Medical Office Building [Member] | Nashville, Tennessee [Member] | Tenant Improvement Allowances [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	1,000
Medical Office Building [Member] | Washington [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	$ 25,211
Approximate square feet | ft²	151,000
Medical Office Building [Member] | Colorado [Member] | Tenant Improvement Allowances [Member]
Property, Plant and Equipment [Line Items]
Total funded during the year	$ 600

Commitments and Contingencies_2

Commitments and Contingencies - Construction Activity (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)ft²property
Other Commitments [Line Items]
NUMBER OF PROP. | property	204
Approximate square feet | ft²	15,400,000
Medical Office Building [Member]
Other Commitments [Line Items]
CONSTRUCTION IN PROGRESS BALANCE	$ 48,731
TOTAL FUNDED during the year	34,243
Total Amount Funded	58,065
ESTIMATED REMAINING FUNDINGS unaudited	33,855
ESTIMATED TOTAL INVESTMENT unaudited	$ 91,920
Approximate square feet | ft²	261,883
Washington [Member] | Medical Office Building [Member]
Other Commitments [Line Items]
NUMBER OF PROP. | property	1
CONSTRUCTION IN PROGRESS BALANCE	$ 48,731
TOTAL FUNDED during the year	25,211
Total Amount Funded	49,033
ESTIMATED REMAINING FUNDINGS unaudited	15,087
ESTIMATED TOTAL INVESTMENT unaudited	$ 64,120
Approximate square feet | ft²	151,000
Memphis, Tennessee [Member] | Medical Office Building [Member]
Other Commitments [Line Items]
NUMBER OF PROP. | property	1
CONSTRUCTION IN PROGRESS BALANCE	$ 0
TOTAL FUNDED during the year	9,032
Total Amount Funded	9,032
ESTIMATED REMAINING FUNDINGS unaudited	18,768
ESTIMATED TOTAL INVESTMENT unaudited	$ 27,800
Approximate square feet | ft²	110,883

Other Data - Narrative (Details

Other Data - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Other Data (Textual) [Abstract]
Condition to qualify as a REIT as defined under the Internal Revenue Code	Company must meet a number of organizational and operational requirements, including a requirement that it currently distribute at least 90% of its taxable income to its stockholders.
Estimated aggregate total cost of total assets for federal income tax purposes	$ 4,400,000,000	$ 4,000,000,000	$ 4,000,000,000
Number of preferred shares outstanding (shares)	0	0
Dividends distributed to preferred shares	$ 0

Other Data (Details)

Other Data (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Net income	$ 39,185	$ 69,771	$ 23,092
Reconciling items to taxable income
Depreciation and amortization	67,953	64,775	46,426
Gain or loss on disposition of depreciable assets	(15,689)	(27,581)	1,570
Straight-line rent	(11,535)	(3,049)	(4,551)
Receivable allowances	1,942	2,470	1,680
Share-based compensation	2,628	(1,699)	1,855
Other	12,631	842	6,552
Reconciling items to taxable income, total	57,930	35,758	53,532
Taxable income	97,115	105,529	76,624
Dividends paid	$ 155,358	$ 150,266	$ 142,327

Other Data - Characterization o

Other Data - Characterization of Distributions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Characterization of distributions on common stock
Ordinary income (in USD per share)	$ 0.79	$ 0.75	$ 0.42
Return of capital (in USD per share)	0.40	0.33	0.50
Unrecaptured section 1250 gain (in USD per share)	0.01	0.12	0.28
Common stock distributions(in USD per share)	$ 1.20	$ 1.20	$ 1.20
Ordinary income in percent of common stock distribution	65.70%	62.20%	34.50%
Return of capital in percent of common stock distribution	33.90%	27.80%	42.00%
Unrecaptured section 1250 gain in percent of common stock distribution	0.40%	10.00%	23.50%
Common stock distribution in percentage	100.00%	100.00%	100.00%

Other Data - State Income Taxes

Other Data - State Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
State income tax expense
Texas gross margins tax	$ 550	$ 586	$ 608
Total state income tax expense	550	586	608
State income tax payments, net of refunds and collections	$ 543	$ 637	$ 555

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes and bonds payable	$ 1,414.1	$ 1,346
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes and bonds payable	$ 1,425.8	$ 1,326.5

Selected Quarterly Financial _3

Selected Quarterly Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Summary of quarterly financial information
Revenues	$ 121,524	$ 119,799	$ 116,317	$ 112,657	$ 113,168	$ 113,462	$ 111,634	$ 112,124	$ 470,298	$ 450,389	$ 424,737
Net income attributable to common stockholders	$ 27,210	$ 2,601	$ 4,484	$ 4,891	$ 16,314	$ 6,548	$ 37,729	$ 9,180
Net income attributable to common stockholders per share
Basic earnings per common share (in USD per share)	$ 0.20	$ 0.02	$ 0.03	$ 0.04	$ 0.13	$ 0.05	$ 0.30	$ 0.07	$ 0.29	$ 0.55	$ 0.18
Diluted earnings per common share (in USD per share)	$ 0.20	$ 0.02	$ 0.03	$ 0.04	$ 0.13	$ 0.05	$ 0.30	$ 0.07	$ 0.29	$ 0.55	$ 0.18

Selected Quarterly Financial _4

Selected Quarterly Financial Data (unaudited) - Narrative (Details) $ in Thousands	3 Months Ended			12 Months Ended
	Dec. 31, 2019USD ($)Property	Dec. 31, 2018USD ($)Property	Jun. 30, 2018USD ($)Property	Dec. 31, 2019USD ($)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Quarterly Financial Information Disclosure [Abstract]
Gain on sales of real estate assets | $	$ 20,000	$ 10,800	$ 27,700	$ 25,101	$ 41,665	$ 39,524
Number of properties sold | Property	6	3	12

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - Accounts receivable allowance [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of period	$ 251	$ 256	$ 148
Charged/(Credited) to costs and expenses, additions and deductions	167	60	159
Charged to other accounts, additions and deductions	0	0	0
Uncollectible accounts written-off	0	65	51
Balance at end of period	$ 418	$ 251	$ 256

Schedule III - Real Estate an_2

Schedule III - Real Estate and Accumulated Depreciation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)propertyProperty	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Summary of real estate properties
NUMBER OF PROP. | property	204
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
Gross real estate asset, Total	$ 4,359,993	$ 3,993,427	$ 3,907,010	$ 3,633,993
Accumulated depreciation	$ 1,121,102	$ 1,025,831	$ 933,220	$ 843,816
Medical Office [Member] | Minimum [Member]
Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date Acquired	Jan. 1, 1993
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date of Construction	Jan. 1, 1906
Medical Office [Member] | Maximum [Member]
Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date Acquired	Dec. 31, 2017
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date of Construction	Dec. 31, 2015
Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	204
LAND 1
INITIAL INVESTMENT	$ 274,121
COST CAPITALIZED subsequent to acquisition	10,408
TOTAL	284,529
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	3,361,046
COST CAPITALIZED subsequent to acquisition	621,470
TOTAL	3,982,516
PERSONAL PROPERTY	5,038
Gross real estate asset, Total	4,272,083
Accumulated depreciation	1,115,695
Encumbrances	$ 129,343
Construction in Progress [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	0
LAND 1
INITIAL INVESTMENT	$ 0
COST CAPITALIZED subsequent to acquisition	0
TOTAL	0
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	0
COST CAPITALIZED subsequent to acquisition	0
TOTAL	48,731
PERSONAL PROPERTY	0
Gross real estate asset, Total	48,731
Accumulated depreciation
Encumbrances	$ 0
Land Held for Development [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	0
LAND 1
INITIAL INVESTMENT	$ 24,647
COST CAPITALIZED subsequent to acquisition	0
TOTAL	24,647
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	0
COST CAPITALIZED subsequent to acquisition	0
TOTAL	0
PERSONAL PROPERTY	0
Gross real estate asset, Total	24,647
Accumulated depreciation	671
Encumbrances	$ 0
Memphis Redevelopment [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	0
LAND 1
INITIAL INVESTMENT	$ 5,222
COST CAPITALIZED subsequent to acquisition	0
TOTAL	5,222
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	3,810
COST CAPITALIZED subsequent to acquisition	0
TOTAL	3,810
PERSONAL PROPERTY	0
Gross real estate asset, Total	9,032
Accumulated depreciation	50
Encumbrances	$ 0
Corporate Property [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	0
LAND 1
INITIAL INVESTMENT	$ 0
COST CAPITALIZED subsequent to acquisition	0
TOTAL	0
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	0
COST CAPITALIZED subsequent to acquisition	0
TOTAL	0
PERSONAL PROPERTY	5,500
Gross real estate asset, Total	5,500
Accumulated depreciation	4,686
Encumbrances	$ 0
Owned Property [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	204
LAND 1
INITIAL INVESTMENT	$ 303,990
COST CAPITALIZED subsequent to acquisition	10,408
TOTAL	314,398
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	3,364,856
COST CAPITALIZED subsequent to acquisition	621,470
TOTAL	4,035,057
PERSONAL PROPERTY	10,538
Gross real estate asset, Total	4,359,993
Accumulated depreciation	1,121,102
Encumbrances	$ 129,343
Inpatient Rehab [Member] | Minimum [Member]
Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date Acquired	Jan. 1, 1994
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date of Construction	Jan. 1, 1986
Inpatient Rehab [Member] | Maximum [Member]
Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date Acquired	Dec. 31, 2013
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date of Construction	Dec. 31, 2013
Other Investments [Member] | Minimum [Member]
Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date Acquired	Jan. 1, 1993
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date of Construction	Jan. 1, 1964
Other Investments [Member] | Maximum [Member]
Real Estate and Accumulated Depreciation [Line Items]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date Acquired	Dec. 31, 2015
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation, Date of Construction	Dec. 31, 2015
Washington [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	25
LAND 1
INITIAL INVESTMENT	$ 54,446
COST CAPITALIZED subsequent to acquisition	4,119
TOTAL	58,565
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	490,461
COST CAPITALIZED subsequent to acquisition	42,306
TOTAL	532,767
PERSONAL PROPERTY	421
Gross real estate asset, Total	591,753
Accumulated depreciation	88,890
Encumbrances	$ 22,666
Dallas, Texas [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	25
LAND 1
INITIAL INVESTMENT	$ 18,785
COST CAPITALIZED subsequent to acquisition	409
TOTAL	19,194
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	372,644
COST CAPITALIZED subsequent to acquisition	124,039
TOTAL	496,683
PERSONAL PROPERTY	442
Gross real estate asset, Total	516,319
Accumulated depreciation	181,556
Encumbrances	$ 0
Los Angeles, California [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	14
LAND 1
INITIAL INVESTMENT	$ 43,719
COST CAPITALIZED subsequent to acquisition	667
TOTAL	44,386
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	161,322
COST CAPITALIZED subsequent to acquisition	44,507
TOTAL	205,829
PERSONAL PROPERTY	347
Gross real estate asset, Total	250,562
Accumulated depreciation	95,979
Encumbrances	$ 22,340
Georgia [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	9
LAND 1
INITIAL INVESTMENT	$ 3,251
COST CAPITALIZED subsequent to acquisition	428
TOTAL	3,679
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	209,400
COST CAPITALIZED subsequent to acquisition	3,109
TOTAL	212,509
PERSONAL PROPERTY	84
Gross real estate asset, Total	216,272
Accumulated depreciation	20,040
Encumbrances	$ 31,715
Nashville, Tennessee [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	6
LAND 1
INITIAL INVESTMENT	$ 20,004
COST CAPITALIZED subsequent to acquisition	49
TOTAL	20,053
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	115,061
COST CAPITALIZED subsequent to acquisition	65,402
TOTAL	180,463
PERSONAL PROPERTY	1,109
Gross real estate asset, Total	201,625
Accumulated depreciation	64,038
Encumbrances	$ 0
North Carolina [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	16
LAND 1
INITIAL INVESTMENT	$ 4,163
COST CAPITALIZED subsequent to acquisition	37
TOTAL	4,200
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	159,340
COST CAPITALIZED subsequent to acquisition	16,921
TOTAL	176,261
PERSONAL PROPERTY	105
Gross real estate asset, Total	180,566
Accumulated depreciation	67,040
Encumbrances	$ 0
Colorado [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	9
LAND 1
INITIAL INVESTMENT	$ 13,887
COST CAPITALIZED subsequent to acquisition	2,627
TOTAL	16,514
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	106,183
COST CAPITALIZED subsequent to acquisition	27,821
TOTAL	134,004
PERSONAL PROPERTY	271
Gross real estate asset, Total	150,789
Accumulated depreciation	25,265
Encumbrances	$ 7,565
Washington, D.C. [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	6
LAND 1
INITIAL INVESTMENT	$ 0
COST CAPITALIZED subsequent to acquisition	0
TOTAL	0
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	141,467
COST CAPITALIZED subsequent to acquisition	8,837
TOTAL	150,304
PERSONAL PROPERTY	21
Gross real estate asset, Total	150,325
Accumulated depreciation	25,097
Encumbrances	$ 11,707
Virginia [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	7
LAND 1
INITIAL INVESTMENT	$ 0
COST CAPITALIZED subsequent to acquisition	0
TOTAL	0
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	139,636
COST CAPITALIZED subsequent to acquisition	9,496
TOTAL	149,132
PERSONAL PROPERTY	106
Gross real estate asset, Total	149,238
Accumulated depreciation	44,204
Encumbrances	$ 0
Houston, Texas [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	9
LAND 1
INITIAL INVESTMENT	$ 15,475
COST CAPITALIZED subsequent to acquisition	736
TOTAL	16,211
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	107,902
COST CAPITALIZED subsequent to acquisition	24,111
TOTAL	132,013
PERSONAL PROPERTY	78
Gross real estate asset, Total	148,302
Accumulated depreciation	44,229
Encumbrances	$ 0
Hawaii [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	3
LAND 1
INITIAL INVESTMENT	$ 8,314
COST CAPITALIZED subsequent to acquisition	13
TOTAL	8,327
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	93,839
COST CAPITALIZED subsequent to acquisition	41,802
TOTAL	135,641
PERSONAL PROPERTY	159
Gross real estate asset, Total	144,127
Accumulated depreciation	39,165
Encumbrances	$ 0
Iowa [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	7
LAND 1
INITIAL INVESTMENT	$ 12,584
COST CAPITALIZED subsequent to acquisition	81
TOTAL	12,665
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	114,527
COST CAPITALIZED subsequent to acquisition	11,874
TOTAL	126,401
PERSONAL PROPERTY	99
Gross real estate asset, Total	139,165
Accumulated depreciation	34,725
Encumbrances	$ 515
Oklahoma [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	4
LAND 1
INITIAL INVESTMENT	$ 9,838
COST CAPITALIZED subsequent to acquisition	563
TOTAL	10,401
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	114,212
COST CAPITALIZED subsequent to acquisition	1,494
TOTAL	115,706
PERSONAL PROPERTY	15
Gross real estate asset, Total	126,122
Accumulated depreciation	19,351
Encumbrances	$ 5,985
Indiana [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	4
LAND 1
INITIAL INVESTMENT	$ 3,299
COST CAPITALIZED subsequent to acquisition	0
TOTAL	3,299
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	112,718
COST CAPITALIZED subsequent to acquisition	6,129
TOTAL	118,847
PERSONAL PROPERTY	0
Gross real estate asset, Total	122,146
Accumulated depreciation	26,082
Encumbrances	$ 0
San Francisco, California [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	3
LAND 1
INITIAL INVESTMENT	$ 14,054
COST CAPITALIZED subsequent to acquisition	0
TOTAL	14,054
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	93,852
COST CAPITALIZED subsequent to acquisition	13,544
TOTAL	107,396
PERSONAL PROPERTY	43
Gross real estate asset, Total	121,493
Accumulated depreciation	20,906
Encumbrances	$ 0
Missouri [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	1
LAND 1
INITIAL INVESTMENT	$ 1,989
COST CAPITALIZED subsequent to acquisition	0
TOTAL	1,989
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	109,304
COST CAPITALIZED subsequent to acquisition	0
TOTAL	109,304
PERSONAL PROPERTY	0
Gross real estate asset, Total	111,293
Accumulated depreciation	17,740
Encumbrances	$ 0
Austin, Texas [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	5
LAND 1
INITIAL INVESTMENT	$ 14,233
COST CAPITALIZED subsequent to acquisition	3
TOTAL	14,236
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	70,976
COST CAPITALIZED subsequent to acquisition	21,833
TOTAL	92,809
PERSONAL PROPERTY	123
Gross real estate asset, Total	107,168
Accumulated depreciation	24,048
Encumbrances	$ 0
Memphis, Tennessee [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	7
LAND 1
INITIAL INVESTMENT	$ 5,241
COST CAPITALIZED subsequent to acquisition	0
TOTAL	5,241
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	66,868
COST CAPITALIZED subsequent to acquisition	25,640
TOTAL	92,508
PERSONAL PROPERTY	194
Gross real estate asset, Total	97,943
Accumulated depreciation	37,582
Encumbrances	$ 0
San Antonio, Texas [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	6
LAND 1
INITIAL INVESTMENT	$ 6,456
COST CAPITALIZED subsequent to acquisition	31
TOTAL	6,487
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	62,161
COST CAPITALIZED subsequent to acquisition	26,422
TOTAL	88,583
PERSONAL PROPERTY	404
Gross real estate asset, Total	95,474
Accumulated depreciation	40,573
Encumbrances	$ 0
Illinois [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	3
LAND 1
INITIAL INVESTMENT	$ 5,859
COST CAPITALIZED subsequent to acquisition	0
TOTAL	5,859
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	69,993
COST CAPITALIZED subsequent to acquisition	17,595
TOTAL	87,588
PERSONAL PROPERTY	211
Gross real estate asset, Total	93,658
Accumulated depreciation	23,540
Encumbrances	$ 0
Minnesota [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	4
LAND 1
INITIAL INVESTMENT	$ 2,090
COST CAPITALIZED subsequent to acquisition	0
TOTAL	2,090
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	61,078
COST CAPITALIZED subsequent to acquisition	1,281
TOTAL	62,359
PERSONAL PROPERTY	0
Gross real estate asset, Total	64,449
Accumulated depreciation	10,486
Encumbrances	$ 18,907
Other (16 MSAs) [Member] | Real Estate [Member]
Summary of real estate properties
NUMBER OF PROP. | Property	31
LAND 1
INITIAL INVESTMENT	$ 16,434
COST CAPITALIZED subsequent to acquisition	645
TOTAL	17,079
BUILDINGS, IMPROVEMENTS, LEASE INTANGIBLES AND CIP 1
INITIAL INVESTMENT	388,102
COST CAPITALIZED subsequent to acquisition	87,307
TOTAL	475,409
PERSONAL PROPERTY	806
Gross real estate asset, Total	493,294
Accumulated depreciation	165,159
Encumbrances	$ 7,943

Schedule III - Real Estate an_3

Schedule III - Real Estate and Accumulated Depreciation (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Beginning Balance, Total Property	$ 3,993,427	$ 3,907,010	$ 3,633,993
Retirement/dispositions
Ending Balance, Total Property	4,359,993	3,993,427	3,907,010
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Beginning Balance, Accumulated Depreciation	1,025,831	933,220	843,816
Retirement/dispositions
Ending Balance, Accumulated Depreciation	1,121,102	1,025,831	933,220
Real Estate [Member]
Additions during the period
Total Property	384,762	112,591	322,616
Retirement/dispositions
TOTAL PROPERTY	(105,487)	(132,665)	(123,639)
Ending Balance, Total Property	4,272,083
Additions during the period
Accumulated Depreciation	9,285	4,175	4,206
Retirement/dispositions
Accumulated Depreciation	(79,659)	(69,102)	(50,683)
Ending Balance, Accumulated Depreciation	1,115,695
Other improvements [Member]
Additions during the period
Total Property	71,666	74,317	59,442
Additions during the period
Accumulated Depreciation	165,367	157,385	135,807
Land Held for Development [Member]
Additions during the period
Total Property	0	4,525	0
Retirement/dispositions
TOTAL PROPERTY	0	0	0
Additions during the period
Accumulated Depreciation	278	153	74
Retirement/dispositions
Accumulated Depreciation		0	0
Construction in Progress [Member]
Additions during the period
Total Property	15,625	27,649	14,598
Retirement/dispositions
Ending Balance, Total Property	48,731
Additions during the period
Accumulated Depreciation	0	$ 0	$ 0
Retirement/dispositions
Ending Balance, Accumulated Depreciation

Schedule III - Real Estate an_4

Schedule III - Real Estate and Accumulated Depreciation - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2019USD ($)property	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Number of real estate assets held for sale | property	0
Estimated aggregate total cost of total assets for federal income tax purposes	$ 4,400,000	$ 4,000,000	$ 4,000,000
Issuance costs	$ 5,841
Minimum [Member] | Building and improvements
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Asset estimated useful life	3 years 3 months 18 days
Minimum [Member] | Lease intangibles
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Asset estimated useful life	2 years 1 month 6 days
Minimum [Member] | Personal Property
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Asset estimated useful life	2 years 9 months 18 days
Minimum [Member] | Land improvements
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Asset estimated useful life	3 years
Maximum [Member] | Building and improvements
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Asset estimated useful life	39 years
Maximum [Member] | Lease intangibles
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Asset estimated useful life	99 years
Maximum [Member] | Personal Property
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Asset estimated useful life	20 years
Maximum [Member] | Land improvements
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Asset estimated useful life	39 years
Mortgage Notes [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Issuance costs	$ 500
Mortgage Notes Payable [Member] | Mortgage Notes [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Unamortized premium	1,162	1,805
Unaccreted discount	528	968
Issuance costs	$ 549	$ 744