Healthcare Realty Trust 10-K 13 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Feb. 08, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Entity Registrant Name	HEALTHCARE REALTY TRUST INCORPORATED
Entity Central Index Key	899,749
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Document Fiscal Year Focus	2,018
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 Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		125,294,458
Entity Public Float			$ 3,548,286,261

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Real estate properties:
Land	$ 230,206	$ 201,283
Buildings, improvements and lease intangibles	3,675,415	3,601,460
Personal property	10,696	10,314
Construction in progress	33,107	5,458
Land held for development	24,647	20,123
Total real estate properties	3,974,071	3,838,638
Less accumulated depreciation	(1,015,174)	(897,430)
Total real estate properties, net	2,958,897	2,941,208
Cash and cash equivalents	8,381	6,215
Assets held for sale, net	9,272	33,147
Other assets, net	214,697	213,015
Total assets	3,191,247	3,193,585
Liabilities:
Notes and bonds payable	1,345,984	1,283,880
Accounts payable and accrued liabilities	80,411	70,995
Liabilities of properties held for sale	587	93
Other liabilities	47,623	48,734
Total liabilities	1,474,605	1,403,702
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; 125,279 and 125,132 shares issued and outstanding at December 31, 2018 and 2017, respectively.	1,253	1,251
Additional paid-in capital	3,180,284	3,173,429
Accumulated other comprehensive loss	(902)	(1,299)
Cumulative net income attributable to common stockholders	1,088,119	1,018,348
Cumulative dividends	(2,552,112)	(2,401,846)
Total stockholders’ equity	1,716,642	1,789,883
Total liabilities and stockholders' equity	$ 3,191,247	$ 3,193,585

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars 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	125,279,000	125,132,000
Common stock, outstanding shares (shares)	125,279,000	125,132,000

Consolidated Statements of Inco

Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
REVENUES
Rental income	$ 442,397	$ 416,978	$ 402,205
Other operating	7,992	7,759	9,750
Total Revenue	450,389	424,737	411,955
EXPENSES
Property operating	170,506	157,252	146,529
General and administrative	34,511	32,992	31,309
Acquisition and pursuit costs	738	2,180	4,496
Depreciation and amortization	164,201	142,472	127,690
Bad debt, net of recoveries	60	159	(21)
Total Expenses	370,016	335,055	310,003
OTHER INCOME (EXPENSE)
Gain on sales of real estate assets	41,665	39,524	41,044
Interest Expense	(52,804)	(56,402)	(57,351)
Loss on extinguishment of debt		(44,985)
Pension termination			(4)
Impairment of real estate assets		(5,385)	(121)
Interest and other income, net	537	658	51
Total other income (expense)	(10,602)	(66,590)	(16,381)
NET INCOME	$ 69,771	$ 23,092	$ 85,571
Basic earnings per common share (dollars per share)	$ 0.55	$ 0.18	$ 0.79
Diluted earnings per common share (dollars per share)	$ 0.55	$ 0.18	$ 0.78
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)	123,292,125	117,926,158	108,572,102
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)	123,350,933	118,017,165	109,386,997

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
NET INCOME	$ 69,771	$ 23,092	$ 85,571
Other comprehensive income (loss):
Reclassification adjustment for losses included in net income (Interest expense)	424	176	168
Losses arising during the period	(27)	(74)
Other comprehensive income	397	102	168
COMPREHENSIVE INCOME	$ 70,168	$ 23,194	$ 85,739

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) $ in Thousands	Preferred Stock	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Cumulative Net Income	Cumulative Dividends	Total Stockholders' Equity
Beginning Balance at Dec. 31, 2015	$ 0	$ 1,015	$ 2,461,376	$ (1,569)	$ 909,685	$ (2,127,760)	$ 1,242,747
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock, net of costs		140	450,409				450,549
Common stock redemption			(1,460)				(1,460)
Stock-based compensation		9	7,589				7,598
Net income					85,571		85,571
Loss on interest rate swaps				168			168
Dividends to common stockholders ($1.20 per share)						(131,759)	(131,759)
Ending Balance at Dec. 31, 2016	0	1,164	2,917,914	(1,401)	995,256	(2,259,519)	1,653,414
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock, net of costs		84	248,508				248,592
Common stock redemption		(1)	(3,017)				(3,018)
Stock-based compensation		4	10,024				10,028
Net income					23,092		23,092
Loss on interest rate swaps				102			102
Dividends to common stockholders ($1.20 per share)						(142,327)	(142,327)
Ending Balance at Dec. 31, 2017	0	1,251	3,173,429	(1,299)	1,018,348	(2,401,846)	1,789,883
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of stock, net of costs			616				616
Common stock redemption		(1)	(4,449)				(4,450)
Stock-based compensation		3	10,688				10,691
Net income					69,771		69,771
Loss on interest rate swaps				397			397
Dividends to common stockholders ($1.20 per share)						(150,266)	(150,266)
Ending Balance at Dec. 31, 2018	$ 0	$ 1,253	$ 3,180,284	$ (902)	$ 1,088,119	$ (2,552,112)	$ 1,716,642

Consolidated Statements of Eq_2

Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Dividend per share to common stockholders (in dollars per share)	$ 1.20	$ 1.20	$ 1.20
Cumulative Dividends
Dividend per share to common stockholders (in dollars per share)	1.20	1.20	1.20
Total Stockholders' Equity
Dividend per share to common stockholders (in dollars 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, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Net income	$ 69,771	$ 23,092	$ 85,571
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	164,201	142,472	127,690
Other amortization	3,000	3,879	3,351
Share-based compensation	10,691	10,028	7,598
Amortization of straight-line rent receivable	(4,281)	(6,072)	(7,201)
Amortization of straight-line rent liability	1,519	1,497	67
Gain on sales of real estate assets	(41,665)	(39,524)	(41,044)
Loss on extinguishment of debt		44,985
Impairment of real estate assets		5,385	121
Equity from unconsolidated joint ventures (income)	(4)	(7)
Distributions from unconsolidated joint ventures	182
Provision for bad debts, net	60	159	(21)
Changes in operating assets and liabilities:
Other assets	(3,998)	(2,156)	(1,332)
Accounts payable and accrued liabilities	4,731	(7,307)	449
Other liabilities	4,148	3,335	(23,977)
Net cash provided by operating activities	208,355	179,766	151,272
INVESTING ACTIVITIES
Acquisitions of real estate	(104,312)	(274,668)	(224,944)
Development of real estate	(26,728)	(14,911)	(34,719)
Additional long-lived assets	(70,807)	(80,613)	(71,433)
Investment in unconsolidated joint ventures		(8,701)
Proceeds from sales of real estate	96,812	119,426	93,253
Proceeds from notes receivable repayments	8	19	19
Net cash used in investing activities	(105,027)	(259,448)	(237,824)
FINANCING ACTIVITIES
Net borrowings (repayments) on unsecured credit facility	73,000	82,000	(99,000)
Repayment on term loan			(50,000)
Repayments of notes and bonds payable		297,459	11,500
Repayments of notes and bonds payable	(19,850)	(5,829)	(37,910)
Redemption of notes and bonds payable		(442,774)
Dividends paid	(150,266)	(142,327)	(131,759)
Net proceeds from issuance of common stock	611	248,554	450,503
Common stock redemptions	(4,532)	(1,686)	(1,756)
Debt issuance and assumption costs	(125)	(4,007)	(4,621)
Net cash (used in) provided by financing activities	(101,162)	31,390	136,957
Increase (decrease) in cash, cash equivalents and restricted cash	2,166	(48,292)	50,405
Cash, cash equivalents and restricted cash at beginning of period	6,215	54,507	4,102
Cash, cash equivalents and restricted cash at end of period	8,381	6,215	54,507
Supplemental Cash Flow Information:
Interest paid	45,752	64,395	55,878
Mortgage notes payable assumed upon acquisition (adjusted to fair value)	7,995	43,674	13,951
Invoices accrued for construction, tenant improvements and other capitalized costs	12,682	8,303	11,734
Capitalized interest	$ 951	$ 871	$ 1,258

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
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 $4.0 billion in 199 real estate properties, construction in progress, land held for development and corporate property as of December 31, 2018 . The Company’s 199 owned real estate properties are located in 27 states and total approximately 14.8 million square feet. The Company provided property management services to approximately 11.2 million square feet nationwide. Square footage and property count disclosures in this Annual Report on Form 10-K are unaudited. Principles of Consolidation The Consolidated Financial Statements include the accounts of the Company, its wholly owned subsidiaries, joint ventures, partnerships and consolidated variable interest entities (“VIE”) where the Company controls the operating activities of the VIE. In accordance with the consolidation accounting standards, the Company must evaluate each contractual relationship it has with its lessees, borrowers, or others to determine whether or not the contractual arrangement creates a variable interest in those entities. If the Company determines that it has a variable interest and the entity is a VIE, then management must determine whether or not the Company is the primary beneficiary of the VIE, resulting in consolidation of the VIE if the Company is the primary beneficiary. A primary beneficiary has the power to direct those activities of the VIE that most significantly impact its economic performance and has the obligation to absorb the losses of, or receive the benefits from, the VIE. The Company had no interests in VIEs as of December 31, 2018 and 2017 . 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, 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 $4.0 billion as of December 31, 2018 and $3.8 billion as of December 31, 2017 . During 2018 and 2017 , the Company eliminated against accumulated depreciation approximately $9.9 million and $10.2 million , respectively, of fully amortized real estate intangibles that were initially recorded as a component of certain real estate acquisitions. Also during 2018 and 2017 , approximately $0.5 million and $2.6 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, 2018, 2017 and 2016 was $143.8 million , $129.4 million and $116.5 million , respectively. Depreciation and amortization of real estate assets and liabilities in place as of December 31, 2018 , is provided for on a straight-line basis over the asset’s estimated useful life: Land improvements 5.0 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, 2018 . The Company’s investment in six parcels of land held in Texas, Iowa, and Tennessee totaled approximately $20.1 million as of December 31, 2017 . 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. 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, and are amortized over the remaining term of the leases upon acquisition. 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 average 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, 2018 and 2017, the Company had $0.9 million and $1.3 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 had restricted cash during the years ended December 31, 2018 and 2017. However, the Company reinvested the restricted cash for real estate acquisitions prior to the ending balance sheet date. Allowance for Doubtful Accounts and Credit Losses Accounts Receivable Management monitors the aging and collectibility of its accounts receivable balances on an ongoing basis. Whenever deterioration in the timeliness of payment from a tenant or sponsoring health system is noted, management investigates and determines the reason or reasons for the delay. Considering all information gathered, management’s judgment is exercised in determining whether a receivable is potentially uncollectible and, if so, how much or what percentage may be uncollectible. Among the factors management considers in determining collectibility are: the type of contractual arrangement under which the receivable was recorded (e.g., a triple net lease, a gross lease, a property operating agreement, or some other type of agreement); the tenant’s reason for slow payment; industry influences under which the tenant operates; evidence of willingness and ability of the tenant to pay the receivable; credit-worthiness of the tenant; collateral, security deposit, letters of credit or other monies held as security; tenant’s historical payment pattern; other contractual agreements between the tenant and the Company; relationship between the tenant and the Company; the state in which the tenant operates; and the existence of a guarantor and the willingness and ability of the guarantor to pay the receivable. Considering these factors and others, management concludes whether all or some of the aged receivable balance is likely uncollectible. Upon determining that some portion of the receivable is likely uncollectible, the Company records a provision for bad debts for the amount it expects will be uncollectible. When efforts to collect a receivable are exhausted, the receivable amount is charged off against the allowance. The Company does not hold any accounts receivable for sale. 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 2018 and 2017 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. Stock-Based Compensation The Company has various employee and director stock-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. The Employee Stock Purchase Plan features a “look-back” provision which enables the employee to purchase a fixed number of common shares 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, with optional purchase dates occurring once each quarter for 27 months . The Company accounts for awards to its employees under the Employee Stock Purchase Plan based on fair value, using the Black-Scholes model, and generally recognizes expense over the award’s vesting period, net of estimated 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, 2018 , 2017 and 2016 , the Company recognized in general and administrative expenses approximately $0.3 million , $0.2 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. See Note 12 for details on the Company’s stock-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, 2018, 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: (in thousands) Year Ended December 31, Type of Revenue 2018 2017 2016 Parking income $ 6,930 $ 6,611 $ 6,121 Property lease guaranty income 675 726 3,058 Management fee income 273 308 402 Miscellaneous 114 114 169 $ 7,992 $ 7,759 $ 9,750 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 , one and two of the Company’s owned real estate properties as of December 31, 2018 , 2017 and 2016, respectively, were 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. If the minimum return is not achieved through normal operations of the property, the Company calculates and accrues 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) 2018 2017 2016 Property operating income $ 390,256 $ 358,009 $ 331,109 Single-tenant net lease 47,860 52,897 63,895 Straight-line rent 4,281 6,072 7,201 Rental income $ 442,397 $ 416,978 $ 402,205 Operating expense recoveries, included in property operating income, were approximately $81.1 million , $73.4 million and $66.0 million , respectively, for the years ended December 31, 2018 , 2017 and 2016 . 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, 2018. Federal tax returns for the years 2015, 2016 , 2017 and 2018 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. Discontinued Operations The Company sells properties from time to time due to a variety of factors, including among other things, market conditions or the exercise of purchase options by tenants. The Company does not expect these dispositions to meet the amended definition of a discontinued operation as defined in Accounting Standards Update ("ASU") No. 2014-08, "Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity." The Company adopted ASU No. 2014-08 on a prospective basis beginning January 1, 2015 which excluded properties previously in discontinued operations prior to adoption. However, if a sale were to meet the amended definition representing a strategic shift that has or will have a major effect on the Company's operations and financial results, the operating results of the properties that have been sold or are held for sale will be reported as discontinued operations in the Company’s Consolidated Statements of Income for all periods presented. 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 prorata 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 stockholder. 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. Reclassifications Consolidated Statements of Income Certain reclassifications have been made on the Company's Consolidated Statements of Income. After the adoption of ASU 2014-08, the Company's dispositions have not met the updated definition to be reported as discontinued operations. The Company had some residual impact from properties that were identified as discontinued operations prior to the adoption of ASU 2014-08. These amounts are considered immaterial and have been reclassified for the prior year presentations on the Company's Consolidated Statements of Income. Year Ended December 31, 2017 2016 (in thousands) As Previously Reported As Reclassified As Previously Reported As Reclassified EXPENSES Property operating expense $ 157,233 $ 157,252 $ 146,458 $ 146,529 Bad debt, net 169 159 (21 ) (21 ) OTHER INCOME (EXPENSE) Gain on sales of properties $ 39,519 $ 39,524 $ 41,038 $ 41,044 Impairments (5,385 ) (5,385 ) — (121 ) INCOME FROM CONTINUING OPERATIONS $ 23,096 $ 23,092 $ 85,756 $ 85,571 DISCONTINUED OPERATIONS Loss from discontinued operations $ (9 ) $ — $ (71 ) $ — Impairments of real estate assets — — (121 ) — Gain on sales of properties 5 — 7 — LOSS FROM DISCONTINUED OPERATIONS $ (4 ) $ — $ (185 ) $ — New Accounting Pronouncements Accounting Standards Update No. 2014-09 and No. 2015-14 In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, "Revenue from Contracts with Customers," a comprehensive new revenue recognition standard that supersedes most existing revenue recognition guidance, including sales of real estate. This standard's core principle is that a company will recognize revenue when it transfers goods or services to customers in amounts that reflect the consideration to which the company expects to be entitled in exchange for those goods and services. However, leasing contracts, representing the major source of the Company's revenues, are not within the scope of the new standard and will continue to be accounted for under other standards. In August 2015, the FASB issued ASU No. 2015-14, "Revenue from Contracts with Customers (Topic 606); Deferral of the Effective Date." This standard is effective for the Company for annual and interim periods beginning after December 15, 2017. The Company adopted this standard by using the full retrospective adoption method beginning on January 1, 2018. The Company's revenue-producing contracts are primarily leases that are not within the scope of this standard. As a result, the adoption of this standard did not have a material impact on the timing and measurement of the Company's leasing revenues. The Company has identified that parking income, property lease guaranty income and management fee income are within the scope of Topic 606. However, these items were determined to have the same pattern of revenue recognition that the Company had historically recognized. The Company reclassified these amounts along with all other items that are accounted for within the scope of Topic 606 into the Other operating line item on the Company's Consolidated Statements of Income. This line item historically contained the revenue associated with property lease guaranty income, management fee income and other non-lease revenue. The Company reclassified parking income from rental income to other operating. The following table represents the impact of the adoption of this standard on the Company's Consolidated Statements of Income for the years ended December 31, 2017 and 2016: Year Ended December 31, 2017 2016 (in thousands) As Previously Reported As Reclassified As Previously Reported As Reclassified REVENUES Rental income $ 422,852 $ 416,978 $ 407,481 $ 402,205 Other operating 1,647 7,759 4,149 9,750 $ 424,499 $ 424,737 $ 411,630 $ 411,955 OTHER INCOME (EXPENSE) Interest and other income, net $ 896 $ 658 $ 375 $ 51 NET INCOME $ 23,092 $ 23,092 $ 85,571 $ 85,571 Accounting Standards Update No. 2016-02, No. 2018-01 and No. 2018-11 In February 2016, the 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

Property Investments

Property Investments	12 Months Ended
	Dec. 31, 2018
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 Company had gross investments of approximately $4.0 billion in 199 real estate properties, construction in progress, land held for development and corporate property as of December 31, 2018 . The following table summarizes the Company’s investments at December 31, 2018. (Dollars in thousands) Number of Facilities Land Buildings, Improvements,and Lease Intangibles Personal Property Total Accumulated Depreciation Dallas, TX 25 $ 16,911 $ 464,077 $ 430 $ 481,418 $ (166,980 ) Seattle, WA 19 28,867 438,880 419 468,166 (69,148 ) Nashville, TN 6 20,053 176,257 1,041 197,351 (53,052 ) Atlanta, GA 8 1,015 189,167 37 190,219 (11,547 ) Los Angeles, CA 12 27,709 157,496 316 185,521 (87,678 ) Charlotte, NC 16 4,200 162,922 99 167,221 (60,389 ) Denver, CO 9 16,514 131,760 273 148,547 (20,315 ) Richmond, VA 7 — 147,809 106 147,915 (38,288 ) Honolulu, HI 3 8,327 134,037 159 142,523 (34,703 ) Des Moines, IA 7 12,665 127,063 99 139,827 (30,376 ) Houston, TX 8 13,672 118,918 77 132,667 (39,195 ) Oklahoma City, OK 3 9,427 111,452 10 120,889 (14,751 ) San Francisco, CA 3 14,054 105,611 43 119,708 (15,539 ) Springfield, MO 1 1,989 109,304 — 111,293 (14,893 ) Austin, TX 5 14,236 91,816 119 106,171 (20,766 ) Washington, DC 4 — 101,186 8 101,194 (20,701 ) Memphis, TN 7 5,241 90,966 191 96,398 (35,109 ) San Antonio, TX 7 6,647 88,954 378 95,979 (37,877 ) Chicago, IL 3 5,859 86,068 201 92,128 (19,372 ) Indianapolis, IN 3 3,299 72,360 — 75,659 (21,299 ) Minneapolis, MN 4 2,090 61,761 — 63,851 (7,750 ) Other (20 markets) 39 17,431 507,551 1,190 526,172 (190,586 ) 199 230,206 3,675,415 5,196 3,910,817 (1,010,314 ) Land held for development — 24,647 — — 24,647 (393 ) Construction in progress — 33,107 — 33,107 — Corporate property — — 5,500 5,500 (4,467 ) Total real estate investments 199 $ 254,853 $ 3,708,522 $ 10,696 $ 3,974,071 $ (1,015,174 )

Real Estate Leases

Real Estate Leases	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Real Estate Leases	Real Estate Leases Real Estate Leases 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 are 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 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, 2018, 2017 and 2016. 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 approximately $117.1 million in five real estate properties as of December 31, 2018

Acquisitions, Dispositions and

Acquisitions, Dispositions and Mortgage Repayments	12 Months Ended
	Dec. 31, 2018
Acquisitions and Dispositions and Mortgage Repayments [Abstract]
Acquisitions, Dispositions and Mortgage Repayments	Acquisitions, Dispositions and Mortgage Repayments 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 Purchase Price Mortgage (2) Cash (3) Real Other (4) Square (Unaudited) 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 (5) 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 Estimated Useful Life (In millions) (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 14.3 1.3 - 4.2 Below-market lease intangibles (0.1 ) 3.8 Total intangibles 14.2 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 Catholic Health Initiative’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. 2017 Real Estate Acquisitions The following table details the Company's acquisitions for the year ended December 31, 2017 : (Dollars in millions) Type (1) Date Purchase Price Mortgage (2) Cash (3) Real Other (4) Square (Unaudited) Real estate acquisitions St. Paul, MN MOB 3/6/17 $ 13.5 $ — $ 13.5 $ 13.3 $ 0.2 34,608 San Francisco, CA MOB 6/12/17 26.8 — 26.8 26.8 — 75,649 Washington, D.C. MOB 6/13/17 24.0 (12.1 ) 12.5 24.8 (0.2 ) 62,379 Los Angeles, CA MOB 7/31/17 16.3 — 16.7 16.9 (0.2 ) 42,780 Atlanta, GA MOB 11/1/17 25.5 — 25.5 26.3 (0.8 ) 76,944 Atlanta, GA MOB 11/1/17 30.3 — 30.7 30.7 — 74,024 Atlanta, GA (5) MOB 11/1/17 49.7 — 50.9 47.5 3.4 118,180 Atlanta, GA MOB 11/1/17 6.7 — 6.7 6.7 — 19,732 Seattle, WA MOB 11/1/17 12.7 — 12.6 12.8 (0.2 ) 26,345 Atlanta, GA (5) MOB 12/13/17 25.8 (10.5 ) 15.3 22.0 3.8 59,427 Atlanta, GA MOB 12/13/17 15.4 (4.7 ) 10.8 15.7 (0.2 ) 40,171 Atlanta, GA (5) MOB 12/18/17 26.3 (11.8 ) 14.5 24.6 1.7 66,984 Atlanta, GA MOB 12/18/17 14.2 (6.7 ) 7.6 14.5 (0.2 ) 40,324 Chicago, IL MOB 12/18/17 28.7 — 27.7 28.5 (0.8 ) 99,526 Seattle, WA MOB 12/18/17 8.8 — 8.8 9.0 (0.2 ) 32,828 Austin, TX (6) MOB 12/21/17 2.5 — 2.5 2.5 — 7,972 $ 327.2 $ (45.8 ) $ 283.1 $ 322.6 $ 6.3 877,873 ______ (1) MOB = medical office building (2) The mortgage notes payable assumed in the acquisitions do not reflect the fair value adjustments totaling $0.6 million in aggregate 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 "Other" column includes the equity investment in limited liability companies that own two parking garages. (6) The Company acquired additional ownership interests in an existing building bringing the Company's ownership to 69.4% . The following table summarizes the estimated relative fair values of the assets acquired and liabilities assumed in the real estate acquisitions for 2017 as of the acquisition date: Estimated Fair Value Estimated Useful Life (In millions) (In years) Building $ 272.1 15.0 - 37.0 Land 11.7 — Land Improvements 1.6 5.0 - 12.0 Intangibles: At-market lease intangibles 37.2 2.1 - 12.6 Below-market lease intangibles (0.9 ) 8.5 - 15.0 Below-market ground lease intangibles 0.4 36.8 - 99.0 Total intangibles 36.7 Mortgage notes payable assumed, including fair value adjustments (46.4 ) Other assets acquired 0.4 Equity investment in joint ventures 8.7 Accounts payable, accrued liabilities and other liabilities assumed (1.7 ) Total cash paid $ 283.1 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 Sales Price Closing Adjustments Net Net Real Other (3) Gain/ Square Unaudited ) Real estate dispositions 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 Total dispositions $ 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. 2017 Real Estate Asset Dispositions The following table details the Company's dispositions for the year ended December 31, 2017: (Dollars in millions) Type (1) Date Sales Price Closing Adjustments Net Net Real Other (3) Gain/ Square Unaudited ) Real estate dispositions Evansville, IN OTH 3/6/17 $ 6.4 $ — $ 6.4 $ 1.1 $ — $ 5.3 29,500 Columbus, GA (2) MOB 3/7/17 0.6 — 0.6 0.6 — — 12,000 Las Vegas, NV (2) MOB 3/30/17 5.5 (0.7 ) 4.8 2.2 0.3 2.3 18,147 Texas (3 properties) IRF 3/31/17 69.5 (1.6 ) 67.9 46.9 5.2 15.8 169,722 Chicago, IL (4) MOB 6/16/17 0.5 (0.1 ) 0.4 0.4 — — 5,100 San Antonio, TX IRF 6/29/17 14.5 (0.2 ) 14.3 5.1 0.9 8.3 39,786 Roseburg, OR MOB 6/29/17 23.2 (0.6 ) 22.6 14.5 0.3 7.8 62,246 St. Louis, MO MOB 9/7/17 2.5 (0.1 ) 2.4 7.4 0.1 (5.1 ) 79,980 Total dispositions $ 122.7 $ (3.3 ) $ 119.4 $ 78.2 $ 6.8 $ 34.4 416,481 ______ (1) MOB = medical office building; IRF = inpatient rehabilitation facility; OTH = other (2) Previously classified as held for sale. (3) Includes straight-line rent receivables, leasing commissions and lease inducements. (4) The Company recorded an impairment of approximately $0.3 million

Held for Sale

Held for Sale	12 Months Ended
	Dec. 31, 2018
Discontinued Operations and Disposal Groups [Abstract]
Held for Sale and Discontinued Operations	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 in the current period. As of December 31, 2018 and 2017 , the Company had one and eight properties, respectively, 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, 2018 and 2017 . December 31, (Dollars in thousands) 2018 2017 Balance Sheet data Land $ 1,125 $ 4,636 Buildings, improvements and lease intangibles 18,231 63,654 Personal property — 82 19,356 68,372 Accumulated depreciation (10,657 ) (35,790 ) Real estate assets held for sale, net 8,699 32,582 Other assets, net 573 565 Assets held for sale, net $ 9,272 $ 33,147 Accounts payable and accrued liabilities $ 450 $ 38 Other liabilities 137 55 Liabilities of properties held for sale $ 587 $ 93

Impairment Charges

Impairment Charges	12 Months Ended
	Dec. 31, 2018
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 did not record any impairment charges in 2018. The Company recorded impairment charges on properties sold or classified as held for sale for the years ended December 31, 2017 and 2016 totaling $5.4 million and $0.1 million

Other Assets

Other Assets	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 are detailed in the table below: December 31, (Dollars in millions) 2018 2017 Straight-line rent receivables $ 69.5 $ 67.0 Prepaid assets 66.2 65.2 Additional long-lived assets, net 23.5 24.9 Above-market intangible assets, net 16.8 17.9 Accounts receivable 10.0 7.4 Allowance for uncollectible accounts (0.3 ) (0.3 ) Ground lease modification, net 9.9 10.3 Equity investments in joint ventures 8.5 8.7 Goodwill 3.5 3.5 Project costs 2.2 2.0 Debt issuance costs, net (1) 2.2 3.5 Customer relationship intangible assets, net 1.7 1.7 Interest rate swap assets 0.2 — Other 0.8 1.2 $ 214.7 $ 213.0 ______ (1) Includes debt issuance costs related to the Company's Unsecured credit facility due 2020. Unconsolidated Joint Ventures During the fourth quarter of 2017, the Company purchased a non-managing membership interest in two LLCs that own two parking garages in Atlanta, Georgia for $8.7 million which is included in the equity investments in 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, 2018 and 2017 related to its LLCs accounted for under the equity method are shown in the table below: December 31, (Dollars in millions) 2018 2017 Net LLC investments, beginning of period $ 8.7 $ — New investments during the period — 8.7 Equity income (loss) recognized during the period — — Owner distributions (0.2 ) — Net LLC investments, end of period $ 8.5 $ 8.7

Intangible Assets and Liabiliti

Intangible Assets and Liabilities	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 consisted of the following: Gross Balance at December 31, Accumulated Amortization at December 31, Weighted Avg. Remaining Life (Years) Balance Sheet Classification (Dollars in millions) 2018 2017 2018 2017 Goodwill $ 3.5 $ 3.5 $ — $ — N/A Other assets, net Credit facility debt issuance costs 5.4 5.4 3.2 1.9 1.6 Other assets, net Above-market lease intangibles 22.3 22.9 5.5 5.0 59.6 Other assets, net Customer relationship intangibles 2.7 2.6 1.0 0.9 24.6 Other assets, net Below-market lease intangibles (9.3 ) (9.5 ) (4.1 ) (3.5 ) 38.0 Other liabilities Debt issuance costs (1) 9.3 9.3 2.8 1.8 3.7 Notes and bonds payable At-market lease intangibles 114.4 110.0 52.0 41.6 4.8 Real estate properties $ 148.3 $ 144.2 $ 60.4 $ 47.7 16.5 ______ (1) Includes debt issuance costs related to the Company's Unsecured credit facility due 2020. For the years ended December 31, 2018 and 2017, the Company recognized approximately $23.2 million and $16.6 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, 2018 : (Dollars in millions) Future Amortization of Intangibles, net 2019 $ 22.1 2020 15.5 2021 9.6 2022 7.3 2023 4.6

Notes and Bonds Payable

Notes and Bonds Payable	12 Months Ended
	Dec. 31, 2018
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) 2018 2017 Unsecured Credit Facility $ 262,000 $ 189,000 7/20 LIBOR + 1.00% At maturity Monthly Unsecured Term Loan due 2022 (1) 149,183 148,994 12/22 LIBOR + 1.10% At maturity Monthly Senior Notes due 2023 (1) 248,117 247,703 4/23 3.75 % At maturity Semi-Annual Senior Notes due 2025 (1) 248,278 248,044 5/25 3.88 % At maturity Semi-Annual Senior Notes due 2028 (1) 295,198 294,757 1/28 3.63 % At maturity Semi-Annual Mortgage notes payable (2) 143,208 155,382 7/19-5/40 3.31%-6.88% Monthly Monthly $ 1,345,984 $ 1,283,880 ______ (1) Balances are shown net of discounts and unamortized issuance costs. (2) 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, 2018 , the Company was in compliance with its financial covenant provisions under its various debt instruments. Unsecured Credit Facility due 2020 On October 14, 2011, the Company entered into a $700.0 million unsecured credit facility with a syndicate of lenders (the "Unsecured Credit Facility"). On July 29, 2016, the Company entered into the third amendment to the Unsecured Credit Facility to extend the maturity date to July 2020. The credit facility agreement provides the Company with two six -month extension options that could extend the maturity date to July 2021. Each option is subject to an extension fee of 0.075% 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 0.83% to 1.55% ( 1.00% as of December 31, 2018 ). In addition, the Company pays a facility fee per annum on the aggregate amount of commitments ranging from 0.13% to 0.30% ( 0.20% as of December 31, 2018 ). As of December 31, 2018 , the Company had $262.0 million outstanding under the Unsecured Credit Facility with an effective interest rate of approximately 3.50% and had a remaining borrowing capacity of approximately $438.0 million . Unsecured Term Loan due 2022 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 December 18, 2017, the Company entered into an amendment to the unsecured term loan due 2022 (the "Unsecured Term Loan due 2022") with a syndicate of nine lenders to extend the maturity date to December 2022. The Unsecured Term Loan due 2022 bears interest at a rate equal to (x) LIBOR plus (y) a margin ranging from 0.90% to 1.75% ( 1.10% as of December 31, 2018 ) based upon the Company's unsecured debt ratings. Payments under the Unsecured Term Loan due 2022 are interest only, with the full amount of the principal due at maturity. The Unsecured Term Loan due 2022 may be prepaid at any time, without penalty. The Unsecured Term Loan due 2022 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. On December 20, 2017, the Company entered into two interest rate swaps totaling $25.0 million to hedge the 1-month LIBOR portion of the cost of borrowing under the Unsecured Term Loan due 2022 to a fixed interest rate of 2.18% (plus the applicable margin rate) through December 2022. On January 30, 2018, the Company entered into two additional interest rate swaps totaling $50.0 million to hedge the 1-month LIBOR portion of the cost of borrowing under the Unsecured Term Loan due 2022 to a fixed interest rate of 2.46% (plus the applicable margin rate) through December 2022. The outstanding balance on the Unsecured Term Loan due 2022 was $150.0 million as of December 31, 2018 with an effective interest rate of approximately 3.53% including the impact of the interest rate swaps. For each of the years ended December 31, 2018 , 2017 , and 2016 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 2022 on the Company’s Consolidated Balance Sheets as of December 31, 2018 and 2017 : December 31, (Dollars in thousands) 2018 2017 Unsecured Term Loan due 2022 principal balance $ 150,000 $ 150,000 Debt issuance costs (817 ) (1,006 ) Unsecured Term Loan due 2022 carrying amount $ 149,183 $ 148,994 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, 2018 , 2017 and 2016 , 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, 2018 and 2017 : December 31, (Dollars in thousands) 2018 2017 Senior Notes due 2023 face value $ 250,000 $ 250,000 Unaccreted discount (974 ) (1,178 ) Debt issuance costs (909 ) (1,119 ) Senior Notes due 2023 carrying amount $ 248,117 $ 247,703 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, 2018 , 2017 , and 2016 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, 2018 and 2017 : December 31, (Dollars in thousands) 2018 2017 Senior Notes due 2025 face value $ 250,000 $ 250,000 Unaccreted discount (141 ) (160 ) Debt issuance costs (1,581 ) (1,796 ) Senior Notes due 2028 carrying amount $ 248,278 $ 248,044 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, 2018 , 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, 2018 : December 31, (Dollars in thousands) 2018 2017 Senior Notes due 2028 face value $ 300,000 $ 300,000 Unaccreted discount (2,319 ) (2,529 ) Debt issuance costs $ (2,483 ) $ (2,714 ) Senior Notes due 2028 carrying amount $ 295,198 $ 294,757 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, 2018 and 2017 . For the years ended December 31, 2018 , 2017 and 2016 , the Company amortized approximately $0.4 million , $0.3 million and $0.3 million of the discount and $0.8 million , $0.7 million , and $0.9 million of the premium. For the years ended December 31, 2018 , 2017 and 2016, the Company also amortized approximately $0.1 million , $0.1 million , and $0.2 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) 2018 2017 Mortgage notes payable principal balance $ 143,115 $ 154,916 Unamortized premium 1,805 2,651 Unaccreted discount (968 ) (1,332 ) Debt issuance costs (744 ) (853 ) Mortgage notes payable carrying amount $ 143,208 $ 155,382 The following table details the Company’s mortgage notes payable, with related collateral. Original Balance Effective Interest Rate (22) Maturity Date Collateral (23) Principal and Interest Payments (21) Investment in Collateral at December 31, Balance at December 31, (Dollars in millions) 2018 2018 2017 Insurance Co. (1) 7.3 5.54 % 12/18 MOB Monthly/25-yr amort. — — 6.0 Commercial Bank (2) 9.5 5.07 % 3/19 MOB Monthly/5-yr amort. — — 9.3 Commercial Bank (3) 9.4 4.55 % 7/19 MOB Monthly/8-yr amort 27.8 9.0 9.2 Commercial Bank (4) 15.2 7.65 % 7/20 MOB (20) 20.2 12.5 12.7 Life Insurance Co. (5) 7.9 4.00 % 8/20 MOB Monthly/15-yr amort. 20.7 1.3 2.0 Life Insurance Co. (6) 7.3 5.25 % 8/20 MOB Monthly/27-yr amort. 18.0 6.2 6.5 Life Insurance Co. (7) 5.6 4.30 % 1/21 MOB Monthly/10-yr amort. 15.7 4.6 4.8 Commercial Bank (8) 12.9 6.43 % 2/21 MOB Monthly/12-yr amort. 55.1 10.3 10.5 Life Insurance Co. (9) 11.0 3.87 % 11/22 MOB Monthly/7-yr amort. 22.0 10.2 10.4 Life Insurance Co. (10) 12.3 3.86 % 8/23 MOB Monthly/7-yr amort. 25.4 11.2 11.5 Financial Services (11) 12.4 4.27 % 10/23 MOB Monthly/10-yr amort. 24.9 12.0 12.2 Life Insurance Co. (12) 9.0 4.84 % 12/23 MOB,OFC Monthly/10-yr amort. 25.3 7.8 — Life Insurance Co. (13) 13.3 4.13 % 1/24 MOB Monthly/10-yr amort. 21.2 13.0 13.3 Life Insurance Co. (14) 6.8 3.96 % 2/24 MOB Monthly/7-yr amort. 14.5 6.6 6.7 Financial Services (15) 9.7 4.32 % 9/24 MOB Monthly/10-yr amort. 16.5 8.6 8.8 Commercial Bank 11.5 3.71 % 1/26 MOB Monthly/10-yr amort. 38.4 10.1 10.5 Commercial Bank (16) 15.0 5.25 % 4/27 MOB Monthly/20-yr amort. 33.5 8.8 9.6 Municipal Government (17) (18) 11.0 4.79 % (19) MOB Semi-Annual (19) 21.0 11.0 11.4 $ 400.2 $ 143.2 $ 155.4 ______ (1) The Company repaid this mortgage note in October 2018. The Company's unencumbered gross investment was $14.4 million at December 31, 2018. (2) The Company repaid this mortgage note in December 2018. The Company's unencumbered gross investment was $14.1 million at December 31, 2018. (3) The unamortized portion of the $0.3 million premium recorded on this note upon acquisition is included in the balance above. (4) The unaccreted portion of the $2.4 million discount recorded on this note upon acquisition is included in the balance above. (5) The unamortized portion of the $0.3 million premium recorded on this note upon acquisition is included in the balance above. (6) The unamortized portion of the $0.4 million premium recorded on this note upon acquisition is included in the balance above. (7) The unamortized portion of the $0.2 million premium recorded on this note upon acquisition is included in the balance above. (8) The unaccreted portion of the $1.0 million discount recorded on this note upon acquisition is included in the balance above. (9) The unaccreted portion of the $0.1 million discount recorded on this note upon acquisition is included in the balance above. (10) The unaccreted portion of the $0.2 million discount recorded on this note upon acquisition is included in the balance above. (11) The unamortized portion of the $0.4 million premium recorded on this note upon acquisition is included in the balance above. (12) The unamortized portion of the $0.1 million premium recorded on this note upon acquisition is included in the balance above. (13) The unamortized portion of the $0.8 million premium recorded on this note upon acquisition is included in the balance above. (14) The unamortized portion of the $0.2 million premium recorded on this note upon acquisition is included in the balance above. (15) The unamortized portion of the $0.1 million premium recorded on this note upon acquisition is included in the balance above. (16) The unamortized portion of the $0.7 million premium recorded on this note upon acquisition is included in the balance above. (17) Balance consists of three notes secured by the same building. (18) The unamortized portion of the $1.0 million premium recorded on the three notes upon acquisition is included in the balance above. (19) 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. (20) 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. (21) Payable in monthly installments of principal and interest with the final payment due at maturity (unless otherwise noted). (22) The contractual interest rates for the 18 outstanding mortgage notes ranged from 3.3% to 6.9% as of December 31, 2018 . (23) 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, 2018 were as follows: (Dollars in thousands) Principal Maturities Net Accretion/ Amortization (1) Debt Issuance Costs (2) Notes and Bonds Payable % 2019 $ 13,857 $ (250 ) $ (1,067 ) $ 12,540 0.9 % 2020 285,064 (392 ) (1,061 ) 283,611 21.1 % 2021 17,593 (326 ) (1,046 ) 16,221 1.2 % 2022 162,977 (336 ) (1,058 ) 161,583 12.0 % 2023 280,230 (183 ) (697 ) 279,350 20.8 % 2024 and thereafter 595,394 (1,110 ) (1,605 ) 592,679 44.0 % $ 1,355,115 $ (2,597 ) $ (6,534 ) $ 1,345,984 100.0 % ______ (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 17 mortgage notes payable. (2) Excludes approximately $2.2 million

Derivative Financial Instrument

Derivative Financial Instruments	12 Months Ended
	Dec. 31, 2018
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 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. During each of the years ended December 31, 2018 and 2017 the Company entered into two 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 Total interest rate swaps 4 $75.0 During the year ended December 31, 2015, the Company entered into four forward starting interest rate swaps with a total notional value of $225.0 million to hedge the risk of changes in the interest-related cash flows associated with the potential issuance of long-term debt. That debt was issued in April 2015, as discussed in Note 9, and the forward starting interest rate swaps were terminated. As a result, the Company realized a loss at the termination date which was deferred and is being amortized over the term of the Senior Notes due 2025. 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, 2018 and 2017. As of December 31, 2018 As of December 31, 2017 (Dollars in thousands) Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments Interest rate swaps 2017 Other assets, net $ 229 Other liabilities $ (67 ) Interest rate swaps 2018 Other liabilities (68 ) — Total derivatives designated as hedging instruments $ 161 $ (67 ) 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, 2018 related to the Company's outstanding interest rate swaps. Amount of Gain/(Loss) Recognized in OCI on Derivatives Amount of Loss Reclassified from OCI into Income for the Twelve Months Ended December 31, (Dollars in thousands) 2018 2018 2017 Interest rate swaps 2017 $ 246 Interest expense $ 51 $ 7 Interest rate swaps 2018 (273 ) Interest expense 204 — Settled interest rate swaps — Interest expense 169 169 $ (27 ) Total interest expense $ 424 $ 176 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, 2018. The net amounts of derivative assets and liabilities can be reconciled to the tabular disclosure of fair value. The tabular disclosure of fair value provides the location that derivative assets and liabilities are presented on the Company's Consolidated Balance Sheets. Offsetting of Derivative Assets As of December 31, 2018 Gross Amounts Not Offset in the Consolidated Balance Sheets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets presented in the Consolidated Balance Sheets Financial Instruments Cash Collateral Net Amount Derivatives $ 229 $ — $ 229 $ (68 ) $ — $ 161 Offsetting of Derivative Liabilities Gross Amounts Not Offset in the Consolidated Balance Sheets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets presented in the Consolidated Balance Sheets Financial Instruments Cash Collateral Net Amount Derivatives $ (68 ) $ — $ (68 ) $ 68 $ — $ — 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 Company estimates that an additional $40 thousand

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
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, 2018 as follows: Year Ended December 31, 2018 2017 2016 Balance, beginning of year 125,131,593 116,416,900 101,517,009 Issuance of common stock 26,203 8,395,607 14,063,100 Non-vested stock-based awards, net of withheld shares and forfeitures 121,659 319,086 836,791 Balance, end of year 125,279,455 125,131,593 116,416,900 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 Sales Price Per Share Net Proceeds (in millions) 2018 — NA $ — 2017 — NA $ — 2016 4,795,601 $28.31 - $33.66 $ 144.6 On February 19, 2016, the Company entered into sales agreements with five investment banks to allow sales under its at-the-market equity offering program of up to 10,000,000 shares of common stock. A previous sales agreement with one investment bank was terminated effective February 17, 2016. No shares were sold related to this program during 2017 or 2018. On May 5, 2017, the Company entered into a sales agreement with a sixth investment bank in connection with the same allotment of shares. The Company has 5,868,697 authorized shares remaining available to be sold under the current sales agreements as of February 13, 2019 . Dividends Declared During 2018 , the Company declared and paid common stock dividends aggregating $1.20 per share ( $0.30 per share per quarter). On February 12, 2019, the Company declared a quarterly common stock dividend in the amount of $0.30 per share payable on March 8, 2019 to stockholders of record on February 22, 2019. Common Stock Authorization On May 2, 2017, the Company's shareholders approved an amendment to the Company's Articles of Incorporation to increase the number of authorized shares of common stock from 150,000,000 to 300,000,000 . Authorization to Repurchase Common Stock The Company’s Board of Directors has authorized management to repurchase up to 3,000,000 shares of the Company’s common stock. As of December 31, 2018 , the Company had not repurchased any shares under this authorization. The Company may elect, from time to time, to repurchase shares either when market conditions are appropriate or as a means to reinvest excess cash flows. Such purchases, if any, may be made either in the open market or through privately negotiated transactions. Accumulated Other Comprehensive Loss During each of the two years ended December 31, 2018 and 2017, the Company entered into two interest rate swaps to hedge the variable cash flows associated with existing variable-rate debt. The Company recorded losses in accumulated other comprehensive loss of approximately $0.4 million as of December 31, 2018. 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, 2018 and 2017 : Interest Rate Swaps December 31, (Dollars in thousands) 2018 2017 Beginning balance $ (1,299 ) $ (1,401 ) Other comprehensive loss before reclassifications 424 176 Amounts reclassified from accumulated other comprehensive income (loss) (27 ) (74 ) Net current-period other comprehensive income 397 102 Ending balance $ (902 ) $ (1,299 ) The following table represents the details regarding the reclassifications from Accumulated other comprehensive income (loss) during the year ended December 31, 2018 : 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 (Dollars in thousands) Amounts reclassified from accumulated other comprehensive income (loss) related to settled interest rate swaps $ 169 Interest Expense Amounts reclassified from accumulated other comprehensive income (loss) related to current interest rate swaps 255 Interest Expense $ 424

Stock and Other Incentive Plans

Stock and Other Incentive Plans	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [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 (the "2015 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, 2018 and 2017 , the Company had issued a total of 1,711,240 and 1,438,228 restricted shares, respectively, under the 2015 Incentive Plan for compensation-related awards to employees and directors, with a total of 1,788,760 and 2,061,772 , respectively, remaining which had not been issued. 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, 2018 , 2017 and 2016 from the amortization of the value of shares over the vesting period issued to employees and directors was $10.4 million , $9.8 million and $7.4 million , respectively. The following table represents expected amortization of the Company's non-vested shares issued: (Dollars in millions) Future Amortization of Non-Vested Shares 2019 $ 8.6 2020 8.1 2021 7.0 2022 4.5 2023 2.3 2024 and thereafter 2.8 Total $ 33.3 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 2018 , 2017 and 2016 , compensation expense, included in general and administrative expense, resulting from the amortization of non-vested share grants to officers was approximately $5.7 million , $5.0 million , and $4.0 million , respectively. Details of the awards that have been earned from this plan are as follows: • 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. • On December 16, 2016, the Company granted non-vested stock awards for TSR performance to its five named executive officers and five senior vice presidents with a grant date fair value totaling $6.3 million , which were granted in the form of 213,639 non-vested shares, with a five -year vesting period, which will result in annual compensation expense of $1.3 million each of 2019, and 2020, and $1.2 million for 2021, respectively. • On February 16, 2016, the Company granted cash incentive and non-vested performance-based awards totaling $5.8 million to its five named executive officers and five senior vice presidents. The officers could elect cash based awards or non-vested stock awards. Cash awards totaled $1.1 million . The non-vested awards, which the officers elected to receive in lieu of cash, had a grant date fair value totaling $4.7 million , which were granted in the form of 163,788 non-vested shares, with either a three - or five -year vesting period, resulting in annual compensation expense of $1.1 million for the year 2018 and $0.7 million for each of 2019 and 2020, respectively. Long-Term Incentive Program In the first quarter of 2018 and 2017 , 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 $1.2 million and $1.3 million , which was granted in the form of 43,414 non-vested shares and 41,368 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 2018 , 2017 and 2016 , compensation expense resulting from the amortization of non-vested share grants to officers was approximately $1.2 million , $1.1 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 2018 , 2017 and 2016 , the Company issued 33,348 shares, 39,016 shares and 42,256 shares, respectively, to its officers through the salary deferral plan. For 2018 , 2017 and 2016 , compensation expense resulting from the amortization of non-vested share grants to officers was approximately $1.0 million , $1.2 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 2018 , 2017 and 2016 , the Company issued 30,989 shares, 23,231 shares, and 21,374 shares, respectively, to its non-employee directors through the 2015 Incentive Plan. For 2018 , 2017 and 2016 , compensation expense resulting from the amortization of non-vested share grants to directors was approximately $0.8 million , $0.8 million , and $1.0 million , respectively. Other Grants The Company issued three one-time non-vested share grants related to executive management transition in 2016. For 2018 , 2017 and 2016 compensation expense resulting from the amortization of these non-vested share grants to officers was approximately $1.7 million , $1.7 million , and $0.1 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. A summary of the activity under the 2015 Incentive Plan and related information for the three years in the period ended December 31, 2018 follows: Year Ended December 31, (Dollars in thousands, except per share data) 2018 2017 2016 Stock-based awards, beginning of year 1,907,645 1,786,497 1,092,262 Granted 273,012 413,489 885,219 Vested (410,794 ) (292,341 ) (190,984 ) Stock-based awards, end of year 1,769,863 1,907,645 1,786,497 Weighted-average grant date fair value of: Stock-based awards, beginning of year $ 28.44 $ 27.18 $ 24.72 Stock-based awards granted during the year $ 29.72 $ 32.05 $ 29.60 Stock-based awards vested during the year $ 25.32 $ 25.88 $ 24.34 Stock-based awards, end of year $ 29.36 $ 28.44 $ 27.18 Grant date fair value of shares granted during the year $ 8,114 $ 13,254 $ 26,204 The vesting periods for the non-vested shares granted during 2018 ranged from one to eight years with a weighted-average amortization period remaining as of December 31, 2018 of approximately 5.1 years. During 2018 , 2017 and 2016 , the Company withheld 151,353 shares, 94,403 shares and 48,248 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 $0.4 million for each year during 2018 , 2017 and 2016 . 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, 2018 , the Company had issued 591,114 shares under the plan of which 9,487 shares were issued in 2018 , 26,031 shares were issued in 2017 and 9,575 shares were issued in 2016 . 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. Cash received from employees upon exercising options under the Employee Stock Purchase Plan was approximately $0.4 million for the year ended December 31, 2018 , $0.8 million for the year ended December 31, 2017 , and $1.2 million for the year ended December 31, 2016 . A summary of the Employee Stock Purchase Plan activity and related information for the three years in the period ended December 31, 2018 is as follows: Year Ended December 31, (Dollars in thousands, except per share data) 2018 2017 2016 Options outstanding, beginning of year 318,100 316,321 340,958 Granted 203,836 206,824 198,450 Exercised (16,716 ) (32,076 ) (57,924 ) Forfeited (40,897 ) (40,659 ) (22,081 ) Expired (135,790 ) (132,310 ) (143,082 ) Options outstanding and exercisable, end of year 328,533 318,100 316,321 Weighted-average exercise price of: Options outstanding, beginning of year $ 25.00 $ 23.69 $ 20.70 Options granted during the year $ 27.30 $ 25.77 $ 24.07 Options exercised during the year $ 24.01 $ 24.31 $ 21.40 Options forfeited during the year $ 24.06 $ 25.01 $ 23.16 Options expired during the year $ 23.55 $ 23.22 $ 18.11 Options outstanding, end of year $ 24.17 $ 25.00 $ 23.69 Weighted-average fair value of options granted during the year (calculated as of the grant date) $ 7.81 $ 6.31 $ 5.37 Intrinsic value of options exercised during the year $ 71 $ 271 $ 634 Intrinsic value of options outstanding and exercisable (calculated as of December 31) $ 1,402 $ 2,683 $ 2,098 Exercise prices of options outstanding (calculated as of December 31) $ 24.17 $ 25.00 $ 23.69 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. 2018 2017 2016 Risk-free interest rates 1.89 % 1.20 % 1.06 % Expected dividend yields 3.66 % 3.70 % 4.64 % Expected life (in years) 1.45 1.45 1.42 Expected volatility 28.4 % 20.4 % 17.6 % Expected forfeiture rates 85 % 85 % 85 %

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2018
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, 2018 . Year Ended December 31, (Dollars in thousands, except per share data) 2018 2017 2016 Weighted Average Common Shares Weighted average Common Shares outstanding 125,219,773 119,739,216 109,861,580 Non-vested shares (1,927,648 ) (1,813,058 ) (1,289,478 ) Weighted average Common Shares - Basic 123,292,125 117,926,158 108,572,102 Weighted average Common Shares - Basic 123,292,125 117,926,158 108,572,102 Dilutive effect of non-vested shares — — 709,559 Dilutive effect of employee stock purchase plan 58,808 91,007 105,336 Weighted average Common Shares - Diluted 123,350,933 118,017,165 109,386,997 Net Income $ 69,771 $ 23,092 $ 85,571 Dividends paid on nonvested share-based awards (2,320 ) (2,149 ) — Net income applicable to common stockholders $ 67,451 $ 20,943 $ 85,571 Basic Earnings Per Common Share $ 0.55 $ 0.18 $ 0.79 Diluted Earnings Per Common Share $ 0.55 $ 0.18 $ 0.78

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Redevelopment Activity The Company completed the redevelopment and expansion of one of its medical office buildings in Nashville, Tennessee in 2017. The Company spent approximately $6.1 million during the year ended December 31, 2018, including approximately $1.9 million related to overages on tenant improvement projects that have been or will be reimbursed by the tenant. The Company continued the redevelopment of a medical office building in Charlotte, North Carolina, which includes a 38,000 square foot vertical expansion. The Company funded approximately $6.1 million during the year ended December 31, 2018. The Company expects initial occupancy to occur in the second quarter of 2019. Development Activity The Company completed the development of a 99,957 square foot medical office building in Denver, Colorado in 2017. The Company spent approximately $1.8 million during the year ended December 31, 2018 , including approximately $0.1 million related to overages on tenant improvement projects that have been or will be reimbursed by the tenant. The Company anticipates funding additional tenant improvements throughout 2019. The Company continued the development of a 151,000 square foot medical office building in Seattle, Washington. The Company spent approximately $21.5 million on the development during the year ended December 31, 2018. The Company expects initial occupancy to occur in the fourth quarter of 2019. The table below details the Company’s construction activity as of December 31, 2018 . The information included in the table below represents management’s estimates and expectations at December 31, 2018 , which are subject to change. The Company’s disclosures regarding certain projections or estimates of completion dates may not reflect actual results. December 31, 2018 (Dollars in thousands) Number of Properties Initial Occupancy Construction in Progress Balance Total Funded During the Year Total Amount Funded Estimated Remaining Fundings (unaudited) Estimated Total Investment (unaudited) Approximate Square Feet (unaudited) Construction Activity Charlotte, NC 1 Q2 2019 $ 9,586 $ 6,099 $ 9,586 2,414 $ 12,000 38,000 Seattle, WA 1 Q4 2019 23,521 21,549 23,821 40,299 64,120 151,000 Total $ 33,107 $ 27,648 $ 33,407 $ 42,713 $ 76,120 189,000 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, 2018 , the Company had commitments of approximately $29.2 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, 2018 . The Company’s investment in six parcels of land held in Texas, Iowa, and Tennessee totaled approximately $20.1 million as of 2017 . Operating Leases 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 increases related to the Company’s ground leases are generally either stated or based on the Consumer Price Index. Rental expense relating to the operating leases for the years ended December 31, 2018 , 2017 and 2016 was $6.9 million , $6.5 million and $5.8 million , respectively. The Company prepaid 47 ground leases. The amortization of the prepaid rent represented approximately $0.5 million of the Company’s rental expense for the years ended December 31, 2018 , 2017 , and 2016 . 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

Other Data

Other Data	12 Months Ended
	Dec. 31, 2018
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 $4.0 billion , $4.0 billion , and $3.7 billion as of December 31, 2018 , 2017 and 2016, 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, 2018 : Year Ended December 31, (Dollars in thousands) 2018 2017 2016 Net income $ 69,771 $ 23,092 $ 85,571 Reconciling items to taxable income: Depreciation and amortization 64,775 46,426 38,260 Gain or loss on disposition of depreciable assets (27,581 ) 1,570 (32,103 ) Impairments — — 121 Straight-line rent (3,049 ) (4,551 ) (7,101 ) Receivable allowances 2,470 1,680 2,067 Stock-based compensation (1,699 ) 1,855 1,301 Other 842 6,552 2,236 35,758 53,532 4,781 Taxable income (1) $ 105,529 $ 76,624 $ 90,352 Dividends paid $ 150,266 $ 142,327 $ 131,759 ______ (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, 2018 . For the three years ended December 31, 2018 , there were no preferred shares outstanding. As such, no dividends were distributed related to preferred shares for those periods. 2018 2017 2016 Per Share % Per Share % Per Share % Common stock: Ordinary income (1) $ 0.75 62.2 % $ 0.42 34.5 % $ 0.78 65.0 % Return of capital 0.33 27.8 % 0.50 42.0 % 0.35 29.5 % Unrecaptured section 1250 gain 0.12 10.0 % 0.28 23.5 % 0.07 5.5 % 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, 2018 are detailed in the table below: Year Ended December 31, (Dollars in thousands) 2018 2017 2016 State income tax expense: Texas gross margins tax $ 586 $ 608 $ 562 Other — — 2 Total state income tax expense $ 586 $ 608 $ 564 State income tax payments, net of refunds and collections $ 637 $ 555 $ 544

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2018
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. Mortgage notes receivable - The fair value of mortgage notes receivable is estimated based either on cash flow analyses at an assumed market rate of interest or at a rate consistent with the rates on mortgage notes acquired by the Company recently, if any. Borrowings under the Unsecured Credit Facility due 2020 and Unsecured Term Loan due 2022 - 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, 2018 and 2017 . December 31, 2018 December 31, 2017 (Dollars in millions) Carrying Value Fair Value Carrying Value Fair Value Notes and bonds payable (1) $ 1,346.0 $ 1,326.5 $ 1,283.9 $ 1,269.7 ______

Selected Quarterly Financial Da

Selected Quarterly Financial Data (unaudited)	12 Months Ended
	Dec. 31, 2018
Selected Quarterly Financial Information [Abstract]
Selected Quarterly Financial Data (unaudited)	Selected Quarterly Financial Data (unaudited) 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 from continuing operations $ 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 properties. Quarterly financial information for the year ended December 31, 2017 is summarized below. Quarter Ended (Dollars in thousands, except per share data) March 31 (1) June 30 (2) September 30 (3) December 31 (4) 2017 Revenues from continuing operations $ 104,644 $ 105,318 $ 107,025 $ 107,749 Net income attributable to common stockholders $ 31,845 $ 25,224 $ 3,173 $ (37,151 ) Net income attributable to common stockholders per share: Basic earnings per common share $ 0.28 $ 0.22 $ 0.02 $ (0.31 ) Diluted earnings per common share $ 0.28 $ 0.22 $ 0.02 $ (0.31 ) ______ (1) The increases in net income and amounts per share for the first quarter of 2017 are primarily attributable to gains of $23.4 million on the sale of six properties. (2) The increases in net income and amounts per share for the second quarter of 2017 are primarily attributable to gains of $16.1 million on the sale of three properties. (3) The decreases in net income and amounts per share for the third quarter of 2017 are primarily attributable to impairment charges of $5.1 million . (4) The decreases in net income and amounts per share for the fourth quarter of 2017 are primarily attributable to a loss on the extinguishment of debt of $45.0 million

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2018
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, 2018 , 2017 and 2016 (Dollars in thousands) Balance at Beginning of Period Additions and Deductions Uncollectible Accounts Written-off Balance at End of Period Description Charged /(Credited) to Costs and Expenses Charged to Other Accounts 2018 Accounts and notes receivable allowance $ 256 $ 60 $ — $ 65 $ 251 2017 Accounts and notes receivable allowance $ 148 $ 159 $ — $ 51 $ 256 2016 Accounts and notes receivable allowance $ 179 $ (21 ) $ — $ 10 $ 148

Schedule III - Real Estate and

Schedule III - Real Estate and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2018
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, 2018 (Dollars in thousands) Land (1) Buildings, Improvements, Lease Intangibles and CIP (1) Market Number of Properties 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 Constructed Dallas, TX 25 $ 16,668 $ 243 $ 16,911 $ 345,126 $ 118,951 $ 464,077 $ 430 $ 481,418 $ 166,980 $ — 2003-2010 1974-2008 Seattle, WA 19 27,050 1,817 28,867 407,491 31,389 438,880 419 468,166 69,148 31,868 2008-2018 1957-2009 Nashville, TN 6 20,004 49 20,053 115,061 61,196 176,257 1,041 197,351 53,052 — 2004-2018 1960-2015 Atlanta, GA 8 588 427 1,015 187,088 2,079 189,167 37 190,219 11,547 32,597 2017 1999-2014 Los Angela, CA 12 27,281 428 27,709 117,144 40,352 157,496 316 185,521 87,678 23,103 1993-2017 1973-1998 Charlotte, NC 16 4,163 37 4,200 150,022 12,900 162,922 99 167,221 60,389 — 2008-2013 1961-2008 Denver, CO 9 13,887 2,627 16,514 108,206 23,554 131,760 273 148,547 20,315 7,789 2010-2018 1977-2015 Richmond, VA 7 — — — 139,636 8,173 147,809 106 147,915 38,288 — 2011 1992-2005 Honolulu, HI 3 8,314 13 8,327 93,839 40,198 134,037 159 142,523 34,703 — 2003-2004 1975-2010 Des Moines, IA 7 12,584 81 12,665 116,647 10,416 127,063 99 139,827 30,376 1,262 2008-2014 2002-2009 Houston, TX 8 13,408 264 13,672 96,894 22,024 118,918 77 132,667 39,195 — 1993-2014 1984-2012 Oklahoma City, OK 3 9,077 350 9,427 111,043 409 111,452 10 120,889 14,751 6,225 2010-2018 1981-2014 San Francisco, CA 3 14,054 — 14,054 93,852 11,759 105,611 43 119,708 15,539 — 2015-2017 1975-2014 Springfield, MO 1 1,989 — 1,989 109,304 — 109,304 — 111,293 14,893 — 2013 2013 Austin, TX 5 14,233 3 14,236 70,976 20,840 91,816 119 106,171 20,766 — 2007-2015 1972-2015 Washington, D.C. 4 — — — 93,730 7,456 101,186 8 101,194 20,701 11,980 2004-2017 1967-2005 Memphis, TN 7 5,241 — 5,241 68,180 22,786 90,966 191 96,398 35,109 — 1999-2013 1993-2007 San Antonio, TX 7 6,617 30 6,647 62,760 26,194 88,954 378 95,979 37,877 — 1996-2010 1978-2011 Chicago, IL 3 5,859 — 5,859 69,964 16,104 86,068 201 92,128 19,372 — 2004-2018 1993-2009 Indianapolis, IN 3 3,299 — 3,299 68,994 3,366 72,360 — 75,659 21,299 — 2008-2010 2005-2008 Minneapolis, MN 4 2,090 — 2,090 61,078 683 61,761 — 63,851 7,750 19,576 2014-2017 1974-2010 Other (21 markets) 40 18,098 458 18,556 436,620 89,162 525,782 1,190 545,528 201,243 8,808 1993-2016 1906-2009 Total Real Estate 200 224,504 6,827 231,331 3,123,655 569,991 3,693,646 5,196 3,930,173 1,020,971 143,208 Land Held for Develop. — 24,647 — 24,647 — — — — 24,647 393 — Construction in Progress — — — — — — 33,107 — 33,107 — — Corporate Property — — — — — — — 5,500 5,500 4,467 — Total Properties 200 $ 249,151 $ 6,827 $ 255,978 $ 3,123,655 $ 569,991 $ 3,726,753 $ 10,696 $ 3,993,427 $ 1,025,831 $ 143,208 (1) Includes one asset held for sale as of December 31, 2018 of approximately $19.4 million (gross) and accumulated depreciation of $10.7 million . (2) Total properties as of December 31, 2018 have an estimated aggregate total cost of $ 4.0 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 to 2.1 to 99.0 years , personal property over 2.8 to 20.0 years, and land improvements over 5.0 to 39.0 years. (4) Includes unamortized premium of $1.8 million and unaccreted discount of $1.0 million and issuance costs of $0.7 million as of December 31, 2018 . (5) Rollforward of Total Property and Accumulated Depreciation, including assets held for sale, for the year ended December 31, 2018 , 2017 and 2016 follows: Year Ended December 31, 2018 Year Ended December 31, 2017 Year Ended December 31, 2016 (Dollars in thousands) Total Property Accumulated Depreciation Total Property Accumulated Depreciation Total Property Accumulated Depreciation Beginning Balance $ 3,907,010 $ 933,220 $ 3,633,993 $ 843,816 $ 3,382,680 $ 762,996 Additions during the period: Real Estate acquired 112,591 4,175 322,616 4,206 239,265 3,898 Other improvements 74,317 157,385 59,442 135,807 70,595 121,592 Land held for development 4,525 153 — 74 — 26 Construction in Progress 27,649 — 14,598 — 35,596 — Retirement/dispositions: Real Estate (132,665 ) (69,102 ) (123,639 ) (50,683 ) (94,143 ) (44,696 ) Land held for development — — — — — — Ending Balance $ 3,993,427 $ 1,025,831 $ 3,907,010 $ 933,220 $ 3,633,993 $ 843,816

Schedule IV - Mortgage Loans on

Schedule IV - Mortgage Loans on Real Estate	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-29, Real Estate Companies, Investment in Mortgage Loans on Real Estate [Abstract]
Mortgage Loans on Real Estate	Schedule IV – Mortgage Loans on Real Estate as of December 31, 2018 The Company had no mortgage notes receivable outstanding as of December 31, 2018

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
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 $4.0 billion in 199 real estate properties, construction in progress, land held for development and corporate property as of December 31, 2018 . The Company’s 199 owned real estate properties are located in 27 states and total approximately 14.8 million square feet. The Company provided property management services to approximately 11.2 million
Principles of Consolidation	Principles of Consolidation The Consolidated Financial Statements include the accounts of the Company, its wholly owned subsidiaries, joint ventures, partnerships and consolidated variable interest entities (“VIE”) where the Company controls the operating activities of the VIE. In accordance with the consolidation accounting standards, the Company must evaluate each contractual relationship it has with its lessees, borrowers, or others to determine whether or not the contractual arrangement creates a variable interest in those entities. If the Company determines that it has a variable interest and the entity is a VIE, then management must determine whether or not the Company is the primary beneficiary of the VIE, resulting in consolidation of the VIE if the Company is the primary beneficiary. A primary beneficiary has the power to direct those activities of the VIE that most significantly impact its economic performance and has the obligation to absorb the losses of, or receive the benefits from, the VIE. The Company had no interests in VIEs as of December 31, 2018 and 2017 . 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, net in other income (expense) on the Company's Consolidated Financial Statements. See Note 7 for additional information.
Use of Estimates in the Consolidated Financial Statements	Use of Estimates in the Consolidated Financial StatementsPreparation 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
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 $4.0 billion as of December 31, 2018 and $3.8 billion as of December 31, 2017 . During 2018 and 2017 , the Company eliminated against accumulated depreciation approximately $9.9 million and $10.2 million , respectively, of fully amortized real estate intangibles that were initially recorded as a component of certain real estate acquisitions. Also during 2018 and 2017 , approximately $0.5 million and $2.6 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, 2018, 2017 and 2016 was $143.8 million , $129.4 million and $116.5 million , respectively. Depreciation and amortization of real estate assets and liabilities in place as of December 31, 2018 , is provided for on a straight-line basis over the asset’s estimated useful life: Land improvements 5.0 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
Land Held for Development	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, 2018 . The Company’s investment in six parcels of land held in Texas, Iowa, and Tennessee totaled approximately $20.1 million as of December 31, 2017
Asset Impairment	Assets Held for SaleLong-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.Asset ImpairmentThe 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. 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, and are amortized over the remaining term of the leases upon acquisition. 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 average 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, 2018 and 2017, the Company had $0.9 million and $1.3 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 had restricted cash during the years ended December 31, 2018 and 2017. However, the Company reinvested the restricted cash for real estate acquisitions prior to the ending balance sheet date.
Allowance for Doubtful Accounts and Credit Losses	Allowance for Doubtful Accounts and Credit Losses Accounts Receivable Management monitors the aging and collectibility of its accounts receivable balances on an ongoing basis. Whenever deterioration in the timeliness of payment from a tenant or sponsoring health system is noted, management investigates and determines the reason or reasons for the delay. Considering all information gathered, management’s judgment is exercised in determining whether a receivable is potentially uncollectible and, if so, how much or what percentage may be uncollectible. Among the factors management considers in determining collectibility are: the type of contractual arrangement under which the receivable was recorded (e.g., a triple net lease, a gross lease, a property operating agreement, or some other type of agreement); the tenant’s reason for slow payment; industry influences under which the tenant operates; evidence of willingness and ability of the tenant to pay the receivable; credit-worthiness of the tenant; collateral, security deposit, letters of credit or other monies held as security; tenant’s historical payment pattern; other contractual agreements between the tenant and the Company; relationship between the tenant and the Company; the state in which the tenant operates; and the existence of a guarantor and the willingness and ability of the guarantor to pay the receivable. Considering these factors and others, management concludes whether all or some of the aged receivable balance is likely uncollectible. Upon determining that some portion of the receivable is likely uncollectible, the Company records a provision for bad debts for the amount it expects will be uncollectible. When efforts to collect a receivable are exhausted, the receivable amount is charged off against the allowance. The Company does not hold any accounts receivable for sale.
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 2018 and 2017 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.
Stock-based Compensation	Stock-Based Compensation The Company has various employee and director stock-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. The Employee Stock Purchase Plan features a “look-back” provision which enables the employee to purchase a fixed number of common shares 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, with optional purchase dates occurring once each quarter for 27 months . The Company accounts for awards to its employees under the Employee Stock Purchase Plan based on fair value, using the Black-Scholes model, and generally recognizes expense over the award’s vesting period, net of estimated 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, 2018 , 2017 and 2016 , the Company recognized in general and administrative expenses approximately $0.3 million , $0.2 million , and $0.2 million
Accumulated Other Comprehensive Income (Loss)	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, 2018, 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.
Revenue Recognition	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: (in thousands) Year Ended December 31, Type of Revenue 2018 2017 2016 Parking income $ 6,930 $ 6,611 $ 6,121 Property lease guaranty income 675 726 3,058 Management fee income 273 308 402 Miscellaneous 114 114 169 $ 7,992 $ 7,759 $ 9,750 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 , one and two of the Company’s owned real estate properties as of December 31, 2018 , 2017 and 2016, respectively, were 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. If the minimum return is not achieved through normal operations of the property, the Company calculates and accrues 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) 2018 2017 2016 Property operating income $ 390,256 $ 358,009 $ 331,109 Single-tenant net lease 47,860 52,897 63,895 Straight-line rent 4,281 6,072 7,201 Rental income $ 442,397 $ 416,978 $ 402,205 Operating expense recoveries, included in property operating income, were approximately $81.1 million , $73.4 million and $66.0 million , respectively, for the years ended December 31, 2018 , 2017 and 2016 .
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, 2018. Federal tax returns for the years 2015, 2016 , 2017 and 2018
State Income Taxes	State Income TaxesThe 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.
Sales and Use Taxes	Sales and Use TaxesThe 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.
Discontinued Operations	Discontinued OperationsThe Company sells properties from time to time due to a variety of factors, including among other things, market conditions or the exercise of purchase options by tenants. The Company does not expect these dispositions to meet the amended definition of a discontinued operation as defined in Accounting Standards Update ("ASU") No. 2014-08, "Reporting Discontinued Operations and Disclosures of Disposals of Components of an Entity." The Company adopted ASU No. 2014-08 on a prospective basis beginning January 1, 2015 which excluded properties previously in discontinued operations prior to adoption. However, if a sale were to meet the amended definition representing a strategic shift that has or will have a major effect on the Company's operations and financial results, the operating results of the properties that have been sold or are held for sale will be reported as discontinued operations in the Company’s Consolidated Statements of Income for all periods presented.
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 prorata 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 stockholder.
Reclassifications	Reclassifications Consolidated Statements of Income Certain reclassifications have been made on the Company's Consolidated Statements of Income. After the adoption of ASU 2014-08, the Company's dispositions have not met the updated definition to be reported as discontinued operations. The Company had some residual impact from properties that were identified as discontinued operations prior to the adoption of ASU 2014-08. These amounts are considered immaterial and have been reclassified for the prior year presentations on the Company's Consolidated Statements of Income. Year Ended December 31, 2017 2016 (in thousands) As Previously Reported As Reclassified As Previously Reported As Reclassified EXPENSES Property operating expense $ 157,233 $ 157,252 $ 146,458 $ 146,529 Bad debt, net 169 159 (21 ) (21 ) OTHER INCOME (EXPENSE) Gain on sales of properties $ 39,519 $ 39,524 $ 41,038 $ 41,044 Impairments (5,385 ) (5,385 ) — (121 ) INCOME FROM CONTINUING OPERATIONS $ 23,096 $ 23,092 $ 85,756 $ 85,571 DISCONTINUED OPERATIONS Loss from discontinued operations $ (9 ) $ — $ (71 ) $ — Impairments of real estate assets — — (121 ) — Gain on sales of properties 5 — 7 — LOSS FROM DISCONTINUED OPERATIONS $ (4 ) $ — $ (185 ) $ —
New Accounting Pronouncements	New Accounting Pronouncements Accounting Standards Update No. 2014-09 and No. 2015-14 In May 2014, the Financial Accounting Standards Board ("FASB") issued ASU No. 2014-09, "Revenue from Contracts with Customers," a comprehensive new revenue recognition standard that supersedes most existing revenue recognition guidance, including sales of real estate. This standard's core principle is that a company will recognize revenue when it transfers goods or services to customers in amounts that reflect the consideration to which the company expects to be entitled in exchange for those goods and services. However, leasing contracts, representing the major source of the Company's revenues, are not within the scope of the new standard and will continue to be accounted for under other standards. In August 2015, the FASB issued ASU No. 2015-14, "Revenue from Contracts with Customers (Topic 606); Deferral of the Effective Date." This standard is effective for the Company for annual and interim periods beginning after December 15, 2017. The Company adopted this standard by using the full retrospective adoption method beginning on January 1, 2018. The Company's revenue-producing contracts are primarily leases that are not within the scope of this standard. As a result, the adoption of this standard did not have a material impact on the timing and measurement of the Company's leasing revenues. The Company has identified that parking income, property lease guaranty income and management fee income are within the scope of Topic 606. However, these items were determined to have the same pattern of revenue recognition that the Company had historically recognized. The Company reclassified these amounts along with all other items that are accounted for within the scope of Topic 606 into the Other operating line item on the Company's Consolidated Statements of Income. This line item historically contained the revenue associated with property lease guaranty income, management fee income and other non-lease revenue. The Company reclassified parking income from rental income to other operating. The following table represents the impact of the adoption of this standard on the Company's Consolidated Statements of Income for the years ended December 31, 2017 and 2016: Year Ended December 31, 2017 2016 (in thousands) As Previously Reported As Reclassified As Previously Reported As Reclassified REVENUES Rental income $ 422,852 $ 416,978 $ 407,481 $ 402,205 Other operating 1,647 7,759 4,149 9,750 $ 424,499 $ 424,737 $ 411,630 $ 411,955 OTHER INCOME (EXPENSE) Interest and other income, net $ 896 $ 658 $ 375 $ 51 NET INCOME $ 23,092 $ 23,092 $ 85,571 $ 85,571 Accounting Standards Update No. 2016-02, No. 2018-01 and No. 2018-11 In February 2016, the 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 expects to elect. 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, and (b) the 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. 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 will be classified as either finance or operating, with the classification affecting the pattern of expense recognition in the income statement. The Company expects that most of the leases where the Company is the lessee will be recorded on the Company's balance sheet as operating leases. These leases are primarily ground leases, but also include management office leases in third party buildings and certain copier and postage machine leases. The Company utilized a third party to assist in determining the discount rate for its ground leases. The terms of the ground leases generally range from 40 to 99 years with a weighted average remaining lease term remaining of 53.9 years, excluding renewal options. The Company's discount rates ranged from 2.9% for leases expiring in 2019 to 6.2% for leases expiring in 2115. The Company expects to recognize as of January 1, 2019 the present value of its lease payments of $90.0 million to $100.0 million with a corresponding lease liability of $90.0 million to $100.0 million . 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, will be accounted for under Topic 606 and separated from the lease payments. However, the Company will elect the lessor practical expedient allowing the Company to not separate these components when certain conditions are met. The Company does not expect a material impact from the adoption of Topic 842 related to leases where the Company is the lessor. The new standard is effective for the Company on January 1, 2019. Topic 842 provides two transition alternatives. The Company elected to choose the prospective optional transition method available to apply the guidance in Accounting Standards Codification Topic 840 in the comparative periods presented in the year Topic 842 is adopted. Topic 842 includes extensive quantitative and qualitative disclosures as compared to Topic 840, Leases, for both lessees and lessors. 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. The Company is in the initial stages of evaluating the impact from the adoption of this new standard on the Consolidated Financial Statements and related notes. However, operating lease receivables, representing the majority of the Company's receivables, are not within the scope of the new standard. Accounting Standards Update No. 2016-15 In August 2016, the FASB issued ASU No. 2016-15, "Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments." This update clarifies whether the following items should be classified as operating, investing or financing in the statement of cash flows: (i) debt prepayments and extinguishment costs, (ii) settlement of zero-coupon debt, (iii) settlement of contingent consideration, (iv) insurance proceeds, (v) settlement of corporate-owned life insurance and bank-owned life insurance policies, (vi) distributions from equity method investees, (vii) beneficial interest in securitization transactions and (viii) receipts and payments with aspects of more than one class of cash flows. This standard was effective for the Company for annual and interim periods beginning on January 1, 2018 with early adoption permitted on a retrospective transition method to each period presented. The Company adopted this standard effective January 1, 2017. In connection with the adoption of this update, the Company elected to use the cumulative earnings approach to classify distributions when received related to the Company's equity method investments. There was not a material impact on the Company's Consolidated Financial Statements and related notes resulting from the adoption of this standard. Accounting Standards Update No. 2017-01 In January 2017, the FASB issued ASU No. 2017-01, "Business Combinations: Clarifying the Definition of a Business." This update modifies the requirements to meet the definition of a business under Topic 805, "Business Combinations." The amendments provide a screen to determine when an integrated set of assets and activities is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or group of similar identifiable assets, the set is not a business. The Company believes that this amendment will result in most of its real estate acquisitions being accounted for as asset acquisitions rather than business combinations. This standard was effective for the Company for annual and interim periods beginning after December 15, 2017 with early adoption permitted. The Company adopted this standard effective January 1, 2017 and has accounted for acquisitions that occurred during the year as asset acquisitions. The impact to the Consolidated Financial Statements and related notes as a result of the adoption of this standard is primarily related to the difference in the accounting of acquisition costs. When accounting for these costs as a part of an asset acquisition, the Company is permitted to capitalize the costs. The adoption of this standard did not have a material impact on the Consolidated Financial Statements and related notes. 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 does not expect a material impact on the Consolidated Financial Statements and related notes from the adoption of this standard. Accounting Standards Update No. 2017-05 In February 2017, the FASB issued ASU 2017-05, "Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets." This update defines an in-substance nonfinancial asset, unifies guidance related to partial sales of nonfinancial assets, eliminates rules specifically addressing the sales of real estate, removes exception to the financial asset derecognition model and clarifies the accounting for contributions of nonfinancial assets to joint ventures. This standard is effective for the Company for annual and interim periods beginning after December 15, 2017 with early adoption permitted. The Company adopted this standard as of January 1, 2018 using the full retrospective adoption method. However, there was no impact to the Company's Consolidated Financial Statements from the adoption of this standard. Accounting Standards Update No. 2017-09 In May 2017, the FASB issued ASU 2017-09, "Compensation - Stock Compensation - Scope of Modification Accounting." This update provides guidance about which changes to the terms and conditions of share-based awards require an entity to apply modification accounting in Topic 718. This standard is effective for the Company for the annual and interim periods beginning after December 15, 2017 with early adoption permitted. The Company adopted this standard on January 1, 2018. 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, 2018
Accounting Policies [Abstract]
Assets' estimated useful life	Depreciation expense of real estate properties for the three years ended December 31, 2018, 2017 and 2016 was $143.8 million , $129.4 million and $116.5 million , respectively. Depreciation and amortization of real estate assets and liabilities in place as of December 31, 2018 , is provided for on a straight-line basis over the asset’s estimated useful life: Land improvements 5.0 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
Disaggregation of revenue	Below is a detail of the amounts by category: (in thousands) Year Ended December 31, Type of Revenue 2018 2017 2016 Parking income $ 6,930 $ 6,611 $ 6,121 Property lease guaranty income 675 726 3,058 Management fee income 273 308 402 Miscellaneous 114 114 169 $ 7,992 $ 7,759 $ 9,750
Schedule of rental income	The components of rental income are as follows: Year Ended December 31, (Dollars in thousands) 2018 2017 2016 Property operating income $ 390,256 $ 358,009 $ 331,109 Single-tenant net lease 47,860 52,897 63,895 Straight-line rent 4,281 6,072 7,201 Rental income $ 442,397 $ 416,978 $ 402,205
Schedule of reclassified expenses	These amounts are considered immaterial and have been reclassified for the prior year presentations on the Company's Consolidated Statements of Income. Year Ended December 31, 2017 2016 (in thousands) As Previously Reported As Reclassified As Previously Reported As Reclassified EXPENSES Property operating expense $ 157,233 $ 157,252 $ 146,458 $ 146,529 Bad debt, net 169 159 (21 ) (21 ) OTHER INCOME (EXPENSE) Gain on sales of properties $ 39,519 $ 39,524 $ 41,038 $ 41,044 Impairments (5,385 ) (5,385 ) — (121 ) INCOME FROM CONTINUING OPERATIONS $ 23,096 $ 23,092 $ 85,756 $ 85,571 DISCONTINUED OPERATIONS Loss from discontinued operations $ (9 ) $ — $ (71 ) $ — Impairments of real estate assets — — (121 ) — Gain on sales of properties 5 — 7 — LOSS FROM DISCONTINUED OPERATIONS $ (4 ) $ — $ (185 ) $ —
Schedule of previously reported balances	The following table represents the impact of the adoption of this standard on the Company's Consolidated Statements of Income for the years ended December 31, 2017 and 2016: Year Ended December 31, 2017 2016 (in thousands) As Previously Reported As Reclassified As Previously Reported As Reclassified REVENUES Rental income $ 422,852 $ 416,978 $ 407,481 $ 402,205 Other operating 1,647 7,759 4,149 9,750 $ 424,499 $ 424,737 $ 411,630 $ 411,955 OTHER INCOME (EXPENSE) Interest and other income, net $ 896 $ 658 $ 375 $ 51 NET INCOME $ 23,092 $ 23,092 $ 85,571 $ 85,571

Property Investments (Tables)

Property Investments (Tables)	12 Months Ended
	Dec. 31, 2018
Real Estate Investment Property, Net [Abstract]
Property Investment	The following table summarizes the Company’s investments at December 31, 2018. (Dollars in thousands) Number of Facilities Land Buildings, Improvements,and Lease Intangibles Personal Property Total Accumulated Depreciation Dallas, TX 25 $ 16,911 $ 464,077 $ 430 $ 481,418 $ (166,980 ) Seattle, WA 19 28,867 438,880 419 468,166 (69,148 ) Nashville, TN 6 20,053 176,257 1,041 197,351 (53,052 ) Atlanta, GA 8 1,015 189,167 37 190,219 (11,547 ) Los Angeles, CA 12 27,709 157,496 316 185,521 (87,678 ) Charlotte, NC 16 4,200 162,922 99 167,221 (60,389 ) Denver, CO 9 16,514 131,760 273 148,547 (20,315 ) Richmond, VA 7 — 147,809 106 147,915 (38,288 ) Honolulu, HI 3 8,327 134,037 159 142,523 (34,703 ) Des Moines, IA 7 12,665 127,063 99 139,827 (30,376 ) Houston, TX 8 13,672 118,918 77 132,667 (39,195 ) Oklahoma City, OK 3 9,427 111,452 10 120,889 (14,751 ) San Francisco, CA 3 14,054 105,611 43 119,708 (15,539 ) Springfield, MO 1 1,989 109,304 — 111,293 (14,893 ) Austin, TX 5 14,236 91,816 119 106,171 (20,766 ) Washington, DC 4 — 101,186 8 101,194 (20,701 ) Memphis, TN 7 5,241 90,966 191 96,398 (35,109 ) San Antonio, TX 7 6,647 88,954 378 95,979 (37,877 ) Chicago, IL 3 5,859 86,068 201 92,128 (19,372 ) Indianapolis, IN 3 3,299 72,360 — 75,659 (21,299 ) Minneapolis, MN 4 2,090 61,761 — 63,851 (7,750 ) Other (20 markets) 39 17,431 507,551 1,190 526,172 (190,586 ) 199 230,206 3,675,415 5,196 3,910,817 (1,010,314 ) Land held for development — 24,647 — — 24,647 (393 ) Construction in progress — 33,107 — 33,107 — Corporate property — — 5,500 5,500 (4,467 ) Total real estate investments 199 $ 254,853 $ 3,708,522 $ 10,696 $ 3,974,071 $ (1,015,174 )

Real Estate Leases (Tables)

Real Estate Leases (Tables)	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
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, 2018 are 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

Acquisitions, Dispositions an_2

Acquisitions, Dispositions and Mortgage Repayments (Tables)	12 Months Ended
	Dec. 31, 2018
Acquisitions and Dispositions and Mortgage Repayments [Abstract]
Summary of acquisitions	The following table details the Company's acquisitions for the year ended December 31, 2018 : (Dollars in millions) Type (1) Date Purchase Price Mortgage (2) Cash (3) Real Other (4) Square (Unaudited) 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 (5) 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. December 31, 2017 : (Dollars in millions) Type (1) Date Purchase Price Mortgage (2) Cash (3) Real Other (4) Square (Unaudited) Real estate acquisitions St. Paul, MN MOB 3/6/17 $ 13.5 $ — $ 13.5 $ 13.3 $ 0.2 34,608 San Francisco, CA MOB 6/12/17 26.8 — 26.8 26.8 — 75,649 Washington, D.C. MOB 6/13/17 24.0 (12.1 ) 12.5 24.8 (0.2 ) 62,379 Los Angeles, CA MOB 7/31/17 16.3 — 16.7 16.9 (0.2 ) 42,780 Atlanta, GA MOB 11/1/17 25.5 — 25.5 26.3 (0.8 ) 76,944 Atlanta, GA MOB 11/1/17 30.3 — 30.7 30.7 — 74,024 Atlanta, GA (5) MOB 11/1/17 49.7 — 50.9 47.5 3.4 118,180 Atlanta, GA MOB 11/1/17 6.7 — 6.7 6.7 — 19,732 Seattle, WA MOB 11/1/17 12.7 — 12.6 12.8 (0.2 ) 26,345 Atlanta, GA (5) MOB 12/13/17 25.8 (10.5 ) 15.3 22.0 3.8 59,427 Atlanta, GA MOB 12/13/17 15.4 (4.7 ) 10.8 15.7 (0.2 ) 40,171 Atlanta, GA (5) MOB 12/18/17 26.3 (11.8 ) 14.5 24.6 1.7 66,984 Atlanta, GA MOB 12/18/17 14.2 (6.7 ) 7.6 14.5 (0.2 ) 40,324 Chicago, IL MOB 12/18/17 28.7 — 27.7 28.5 (0.8 ) 99,526 Seattle, WA MOB 12/18/17 8.8 — 8.8 9.0 (0.2 ) 32,828 Austin, TX (6) MOB 12/21/17 2.5 — 2.5 2.5 — 7,972 $ 327.2 $ (45.8 ) $ 283.1 $ 322.6 $ 6.3 877,873 ______ (1) MOB = medical office building (2) The mortgage notes payable assumed in the acquisitions do not reflect the fair value adjustments totaling $0.6 million in aggregate 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 "Other" column includes the equity investment in limited liability companies that own two parking garages. (6) The Company acquired additional ownership interests in an existing building bringing the Company's ownership to 69.4%
Summary 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 2017 as of the acquisition date: Estimated Fair Value Estimated Useful Life (In millions) (In years) Building $ 272.1 15.0 - 37.0 Land 11.7 — Land Improvements 1.6 5.0 - 12.0 Intangibles: At-market lease intangibles 37.2 2.1 - 12.6 Below-market lease intangibles (0.9 ) 8.5 - 15.0 Below-market ground lease intangibles 0.4 36.8 - 99.0 Total intangibles 36.7 Mortgage notes payable assumed, including fair value adjustments (46.4 ) Other assets acquired 0.4 Equity investment in joint ventures 8.7 Accounts payable, accrued liabilities and other liabilities assumed (1.7 ) Total cash paid $ 283.1 2018 as of the acquisition date: Estimated Fair Value Estimated Useful Life (In millions) (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 14.3 1.3 - 4.2 Below-market lease intangibles (0.1 ) 3.8 Total intangibles 14.2 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
Summary of dispositions	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 Sales Price Closing Adjustments Net Net Real Other (3) Gain/ Square Unaudited ) Real estate dispositions 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 Total dispositions $ 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. 2017 Real Estate Asset Dispositions The following table details the Company's dispositions for the year ended December 31, 2017: (Dollars in millions) Type (1) Date Sales Price Closing Adjustments Net Net Real Other (3) Gain/ Square Unaudited ) Real estate dispositions Evansville, IN OTH 3/6/17 $ 6.4 $ — $ 6.4 $ 1.1 $ — $ 5.3 29,500 Columbus, GA (2) MOB 3/7/17 0.6 — 0.6 0.6 — — 12,000 Las Vegas, NV (2) MOB 3/30/17 5.5 (0.7 ) 4.8 2.2 0.3 2.3 18,147 Texas (3 properties) IRF 3/31/17 69.5 (1.6 ) 67.9 46.9 5.2 15.8 169,722 Chicago, IL (4) MOB 6/16/17 0.5 (0.1 ) 0.4 0.4 — — 5,100 San Antonio, TX IRF 6/29/17 14.5 (0.2 ) 14.3 5.1 0.9 8.3 39,786 Roseburg, OR MOB 6/29/17 23.2 (0.6 ) 22.6 14.5 0.3 7.8 62,246 St. Louis, MO MOB 9/7/17 2.5 (0.1 ) 2.4 7.4 0.1 (5.1 ) 79,980 Total dispositions $ 122.7 $ (3.3 ) $ 119.4 $ 78.2 $ 6.8 $ 34.4 416,481 ______ (1) MOB = medical office building; IRF = inpatient rehabilitation facility; OTH = other (2) Previously classified as held for sale. (3) Includes straight-line rent receivables, leasing commissions and lease inducements. (4) The Company recorded an impairment of approximately $0.3 million

Held for Sale (Tables)

Held for Sale (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 . December 31, (Dollars in thousands) 2018 2017 Balance Sheet data Land $ 1,125 $ 4,636 Buildings, improvements and lease intangibles 18,231 63,654 Personal property — 82 19,356 68,372 Accumulated depreciation (10,657 ) (35,790 ) Real estate assets held for sale, net 8,699 32,582 Other assets, net 573 565 Assets held for sale, net $ 9,272 $ 33,147 Accounts payable and accrued liabilities $ 450 $ 38 Other liabilities 137 55 Liabilities of properties held for sale $ 587 $ 93

Other Assets (Tables)

Other Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Items included in 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, 2018 and 2017 are detailed in the table below: December 31, (Dollars in millions) 2018 2017 Straight-line rent receivables $ 69.5 $ 67.0 Prepaid assets 66.2 65.2 Additional long-lived assets, net 23.5 24.9 Above-market intangible assets, net 16.8 17.9 Accounts receivable 10.0 7.4 Allowance for uncollectible accounts (0.3 ) (0.3 ) Ground lease modification, net 9.9 10.3 Equity investments in joint ventures 8.5 8.7 Goodwill 3.5 3.5 Project costs 2.2 2.0 Debt issuance costs, net (1) 2.2 3.5 Customer relationship intangible assets, net 1.7 1.7 Interest rate swap assets 0.2 — Other 0.8 1.2 $ 214.7 $ 213.0 ______ (1) Includes debt issuance costs related to the Company's Unsecured credit facility due 2020.
Equity Method Investments	The Company's investment in and income (loss) recognized for the years ended December 31, 2018 and 2017 related to its LLCs accounted for under the equity method are shown in the table below: December 31, (Dollars in millions) 2018 2017 Net LLC investments, beginning of period $ 8.7 $ — New investments during the period — 8.7 Equity income (loss) recognized during the period — — Owner distributions (0.2 ) — Net LLC investments, end of period $ 8.5 $ 8.7

Intangible Assets and Liabili_2

Intangible Assets and Liabilities (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 and 2017 consisted of the following: Gross Balance at December 31, Accumulated Amortization at December 31, Weighted Avg. Remaining Life (Years) Balance Sheet Classification (Dollars in millions) 2018 2017 2018 2017 Goodwill $ 3.5 $ 3.5 $ — $ — N/A Other assets, net Credit facility debt issuance costs 5.4 5.4 3.2 1.9 1.6 Other assets, net Above-market lease intangibles 22.3 22.9 5.5 5.0 59.6 Other assets, net Customer relationship intangibles 2.7 2.6 1.0 0.9 24.6 Other assets, net Below-market lease intangibles (9.3 ) (9.5 ) (4.1 ) (3.5 ) 38.0 Other liabilities Debt issuance costs (1) 9.3 9.3 2.8 1.8 3.7 Notes and bonds payable At-market lease intangibles 114.4 110.0 52.0 41.6 4.8 Real estate properties $ 148.3 $ 144.2 $ 60.4 $ 47.7 16.5 ______ (1)
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, 2018 : (Dollars in millions) Future Amortization of Intangibles, net 2019 $ 22.1 2020 15.5 2021 9.6 2022 7.3 2023 4.6

Notes and Bonds Payable (Tables

Notes and Bonds Payable (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Instrument [Line Items]
Schedule of debt	December 31, Maturity Dates Contractual Interest Rates Principal Payments Interest Payments (Dollars in thousands) 2018 2017 Unsecured Credit Facility $ 262,000 $ 189,000 7/20 LIBOR + 1.00% At maturity Monthly Unsecured Term Loan due 2022 (1) 149,183 148,994 12/22 LIBOR + 1.10% At maturity Monthly Senior Notes due 2023 (1) 248,117 247,703 4/23 3.75 % At maturity Semi-Annual Senior Notes due 2025 (1) 248,278 248,044 5/25 3.88 % At maturity Semi-Annual Senior Notes due 2028 (1) 295,198 294,757 1/28 3.63 % At maturity Semi-Annual Mortgage notes payable (2) 143,208 155,382 7/19-5/40 3.31%-6.88% Monthly Monthly $ 1,345,984 $ 1,283,880 ______ (1) Balances are shown net of discounts and unamortized issuance costs. (2)
Schedule of Mortgage Notes Payable	The following table details the Company’s mortgage notes payable, with related collateral. Original Balance Effective Interest Rate (22) Maturity Date Collateral (23) Principal and Interest Payments (21) Investment in Collateral at December 31, Balance at December 31, (Dollars in millions) 2018 2018 2017 Insurance Co. (1) 7.3 5.54 % 12/18 MOB Monthly/25-yr amort. — — 6.0 Commercial Bank (2) 9.5 5.07 % 3/19 MOB Monthly/5-yr amort. — — 9.3 Commercial Bank (3) 9.4 4.55 % 7/19 MOB Monthly/8-yr amort 27.8 9.0 9.2 Commercial Bank (4) 15.2 7.65 % 7/20 MOB (20) 20.2 12.5 12.7 Life Insurance Co. (5) 7.9 4.00 % 8/20 MOB Monthly/15-yr amort. 20.7 1.3 2.0 Life Insurance Co. (6) 7.3 5.25 % 8/20 MOB Monthly/27-yr amort. 18.0 6.2 6.5 Life Insurance Co. (7) 5.6 4.30 % 1/21 MOB Monthly/10-yr amort. 15.7 4.6 4.8 Commercial Bank (8) 12.9 6.43 % 2/21 MOB Monthly/12-yr amort. 55.1 10.3 10.5 Life Insurance Co. (9) 11.0 3.87 % 11/22 MOB Monthly/7-yr amort. 22.0 10.2 10.4 Life Insurance Co. (10) 12.3 3.86 % 8/23 MOB Monthly/7-yr amort. 25.4 11.2 11.5 Financial Services (11) 12.4 4.27 % 10/23 MOB Monthly/10-yr amort. 24.9 12.0 12.2 Life Insurance Co. (12) 9.0 4.84 % 12/23 MOB,OFC Monthly/10-yr amort. 25.3 7.8 — Life Insurance Co. (13) 13.3 4.13 % 1/24 MOB Monthly/10-yr amort. 21.2 13.0 13.3 Life Insurance Co. (14) 6.8 3.96 % 2/24 MOB Monthly/7-yr amort. 14.5 6.6 6.7 Financial Services (15) 9.7 4.32 % 9/24 MOB Monthly/10-yr amort. 16.5 8.6 8.8 Commercial Bank 11.5 3.71 % 1/26 MOB Monthly/10-yr amort. 38.4 10.1 10.5 Commercial Bank (16) 15.0 5.25 % 4/27 MOB Monthly/20-yr amort. 33.5 8.8 9.6 Municipal Government (17) (18) 11.0 4.79 % (19) MOB Semi-Annual (19) 21.0 11.0 11.4 $ 400.2 $ 143.2 $ 155.4 ______ (1) The Company repaid this mortgage note in October 2018. The Company's unencumbered gross investment was $14.4 million at December 31, 2018. (2) The Company repaid this mortgage note in December 2018. The Company's unencumbered gross investment was $14.1 million at December 31, 2018. (3) The unamortized portion of the $0.3 million premium recorded on this note upon acquisition is included in the balance above. (4) The unaccreted portion of the $2.4 million discount recorded on this note upon acquisition is included in the balance above. (5) The unamortized portion of the $0.3 million premium recorded on this note upon acquisition is included in the balance above. (6) The unamortized portion of the $0.4 million premium recorded on this note upon acquisition is included in the balance above. (7) The unamortized portion of the $0.2 million premium recorded on this note upon acquisition is included in the balance above. (8) The unaccreted portion of the $1.0 million discount recorded on this note upon acquisition is included in the balance above. (9) The unaccreted portion of the $0.1 million discount recorded on this note upon acquisition is included in the balance above. (10) The unaccreted portion of the $0.2 million discount recorded on this note upon acquisition is included in the balance above. (11) The unamortized portion of the $0.4 million premium recorded on this note upon acquisition is included in the balance above. (12) The unamortized portion of the $0.1 million premium recorded on this note upon acquisition is included in the balance above. (13) The unamortized portion of the $0.8 million premium recorded on this note upon acquisition is included in the balance above. (14) The unamortized portion of the $0.2 million premium recorded on this note upon acquisition is included in the balance above. (15) The unamortized portion of the $0.1 million premium recorded on this note upon acquisition is included in the balance above. (16) The unamortized portion of the $0.7 million premium recorded on this note upon acquisition is included in the balance above. (17) Balance consists of three notes secured by the same building. (18) The unamortized portion of the $1.0 million premium recorded on the three notes upon acquisition is included in the balance above. (19) 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. (20) 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. (21) Payable in monthly installments of principal and interest with the final payment due at maturity (unless otherwise noted). (22) The contractual interest rates for the 18 outstanding mortgage notes ranged from 3.3% to 6.9% as of December 31, 2018 . (23)
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, 2018 were as follows: (Dollars in thousands) Principal Maturities Net Accretion/ Amortization (1) Debt Issuance Costs (2) Notes and Bonds Payable % 2019 $ 13,857 $ (250 ) $ (1,067 ) $ 12,540 0.9 % 2020 285,064 (392 ) (1,061 ) 283,611 21.1 % 2021 17,593 (326 ) (1,046 ) 16,221 1.2 % 2022 162,977 (336 ) (1,058 ) 161,583 12.0 % 2023 280,230 (183 ) (697 ) 279,350 20.8 % 2024 and thereafter 595,394 (1,110 ) (1,605 ) 592,679 44.0 % $ 1,355,115 $ (2,597 ) $ (6,534 ) $ 1,345,984 100.0 % ______ (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 17 mortgage notes payable. (2) Excludes approximately $2.2 million in debt issuance costs related to the Company's Unsecured Credit Facility included in other assets, net.
Medium-term Notes [Member] | Term Loan due 2022 [Member]
Debt Instrument [Line Items]
Schedule of debt	The following table reconciles the balance of the Unsecured Term Loan due 2022 on the Company’s Consolidated Balance Sheets as of December 31, 2018 and 2017 : December 31, (Dollars in thousands) 2018 2017 Unsecured Term Loan due 2022 principal balance $ 150,000 $ 150,000 Debt issuance costs (817 ) (1,006 ) Unsecured Term Loan due 2022 carrying amount $ 149,183 $ 148,994
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, 2018 and 2017 : December 31, (Dollars in thousands) 2018 2017 Senior Notes due 2023 face value $ 250,000 $ 250,000 Unaccreted discount (974 ) (1,178 ) Debt issuance costs (909 ) (1,119 ) Senior Notes due 2023 carrying amount $ 248,117 $ 247,703
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, 2018 and 2017 : December 31, (Dollars in thousands) 2018 2017 Senior Notes due 2025 face value $ 250,000 $ 250,000 Unaccreted discount (141 ) (160 ) Debt issuance costs (1,581 ) (1,796 ) Senior Notes due 2028 carrying amount $ 248,278 $ 248,044
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, 2018 : December 31, (Dollars in thousands) 2018 2017 Senior Notes due 2028 face value $ 300,000 $ 300,000 Unaccreted discount (2,319 ) (2,529 ) Debt issuance costs $ (2,483 ) $ (2,714 ) Senior Notes due 2028 carrying amount $ 295,198 $ 294,757
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, 2018 and 2017 . For the years ended December 31, 2018 , 2017 and 2016 , the Company amortized approximately $0.4 million , $0.3 million and $0.3 million of the discount and $0.8 million , $0.7 million , and $0.9 million of the premium. For the years ended December 31, 2018 , 2017 and 2016, the Company also amortized approximately $0.1 million , $0.1 million , and $0.2 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) 2018 2017 Mortgage notes payable principal balance $ 143,115 $ 154,916 Unamortized premium 1,805 2,651 Unaccreted discount (968 ) (1,332 ) Debt issuance costs (744 ) (853 ) Mortgage notes payable carrying amount $ 143,208 $ 155,382

Derivative Financial Instrume_2

Derivative Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
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, 2018 related to the Company's outstanding interest rate swaps. Amount of Gain/(Loss) Recognized in OCI on Derivatives Amount of Loss Reclassified from OCI into Income for the Twelve Months Ended December 31, (Dollars in thousands) 2018 2018 2017 Interest rate swaps 2017 $ 246 Interest expense $ 51 $ 7 Interest rate swaps 2018 (273 ) Interest expense 204 — Settled interest rate swaps — Interest expense 169 169 $ (27 ) Total interest expense $ 424 $ 176 December 31, 2018 and 2017 the Company entered into two 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 Total interest rate swaps 4 $75.0
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, 2018 and 2017. As of December 31, 2018 As of December 31, 2017 (Dollars in thousands) Balance Sheet Location Fair Value Balance Sheet Location Fair Value Derivatives designated as hedging instruments Interest rate swaps 2017 Other assets, net $ 229 Other liabilities $ (67 ) Interest rate swaps 2018 Other liabilities (68 ) — Total derivatives designated as hedging instruments $ 161 $ (67 )
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, 2018. The net amounts of derivative assets and liabilities can be reconciled to the tabular disclosure of fair value. The tabular disclosure of fair value provides the location that derivative assets and liabilities are presented on the Company's Consolidated Balance Sheets. Offsetting of Derivative Assets As of December 31, 2018 Gross Amounts Not Offset in the Consolidated Balance Sheets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets presented in the Consolidated Balance Sheets Financial Instruments Cash Collateral Net Amount Derivatives $ 229 $ — $ 229 $ (68 ) $ — $ 161 Offsetting of Derivative Liabilities Gross Amounts Not Offset in the Consolidated Balance Sheets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets presented in the Consolidated Balance Sheets Financial Instruments Cash Collateral Net Amount Derivatives $ (68 ) $ — $ (68 ) $ 68 $ — $ —
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, 2018. The net amounts of derivative assets and liabilities can be reconciled to the tabular disclosure of fair value. The tabular disclosure of fair value provides the location that derivative assets and liabilities are presented on the Company's Consolidated Balance Sheets. Offsetting of Derivative Assets As of December 31, 2018 Gross Amounts Not Offset in the Consolidated Balance Sheets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets presented in the Consolidated Balance Sheets Financial Instruments Cash Collateral Net Amount Derivatives $ 229 $ — $ 229 $ (68 ) $ — $ 161 Offsetting of Derivative Liabilities Gross Amounts Not Offset in the Consolidated Balance Sheets Gross Amounts of Recognized Assets Gross Amounts Offset in the Consolidated Balance Sheets Net Amounts of Assets presented in the Consolidated Balance Sheets Financial Instruments Cash Collateral Net Amount Derivatives $ (68 ) $ — $ (68 ) $ 68 $ — $ —

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Equity [Abstract]
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, 2018 as follows: Year Ended December 31, 2018 2017 2016 Balance, beginning of year 125,131,593 116,416,900 101,517,009 Issuance of common stock 26,203 8,395,607 14,063,100 Non-vested stock-based awards, net of withheld shares and forfeitures 121,659 319,086 836,791 Balance, end of year 125,279,455 125,131,593 116,416,900
Schedule of sale of stock under market equity offering Program	The following table details the shares sold under this program. Shares Sold Sales Price Per Share Net Proceeds (in millions) 2018 — NA $ — 2017 — NA $ — 2016 4,795,601 $28.31 - $33.66 $ 144.6
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, 2018 and 2017 : Interest Rate Swaps December 31, (Dollars in thousands) 2018 2017 Beginning balance $ (1,299 ) $ (1,401 ) Other comprehensive loss before reclassifications 424 176 Amounts reclassified from accumulated other comprehensive income (loss) (27 ) (74 ) Net current-period other comprehensive income 397 102 Ending balance $ (902 ) $ (1,299 )
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, 2018 : 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 (Dollars in thousands) Amounts reclassified from accumulated other comprehensive income (loss) related to settled interest rate swaps $ 169 Interest Expense Amounts reclassified from accumulated other comprehensive income (loss) related to current interest rate swaps 255 Interest Expense $ 424

Stock and Other Incentive Pla_2

Stock and Other Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Unrecognized Compensation Cost, Nonvested Awards	The following table represents expected amortization of the Company's non-vested shares issued: (Dollars in millions) Future Amortization of Non-Vested Shares 2019 $ 8.6 2020 8.1 2021 7.0 2022 4.5 2023 2.3 2024 and thereafter 2.8 Total $ 33.3
Summary 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, 2018 follows: Year Ended December 31, (Dollars in thousands, except per share data) 2018 2017 2016 Stock-based awards, beginning of year 1,907,645 1,786,497 1,092,262 Granted 273,012 413,489 885,219 Vested (410,794 ) (292,341 ) (190,984 ) Stock-based awards, end of year 1,769,863 1,907,645 1,786,497 Weighted-average grant date fair value of: Stock-based awards, beginning of year $ 28.44 $ 27.18 $ 24.72 Stock-based awards granted during the year $ 29.72 $ 32.05 $ 29.60 Stock-based awards vested during the year $ 25.32 $ 25.88 $ 24.34 Stock-based awards, end of year $ 29.36 $ 28.44 $ 27.18 Grant date fair value of shares granted during the year $ 8,114 $ 13,254 $ 26,204
Summary 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, 2018 is as follows: Year Ended December 31, (Dollars in thousands, except per share data) 2018 2017 2016 Options outstanding, beginning of year 318,100 316,321 340,958 Granted 203,836 206,824 198,450 Exercised (16,716 ) (32,076 ) (57,924 ) Forfeited (40,897 ) (40,659 ) (22,081 ) Expired (135,790 ) (132,310 ) (143,082 ) Options outstanding and exercisable, end of year 328,533 318,100 316,321 Weighted-average exercise price of: Options outstanding, beginning of year $ 25.00 $ 23.69 $ 20.70 Options granted during the year $ 27.30 $ 25.77 $ 24.07 Options exercised during the year $ 24.01 $ 24.31 $ 21.40 Options forfeited during the year $ 24.06 $ 25.01 $ 23.16 Options expired during the year $ 23.55 $ 23.22 $ 18.11 Options outstanding, end of year $ 24.17 $ 25.00 $ 23.69 Weighted-average fair value of options granted during the year (calculated as of the grant date) $ 7.81 $ 6.31 $ 5.37 Intrinsic value of options exercised during the year $ 71 $ 271 $ 634 Intrinsic value of options outstanding and exercisable (calculated as of December 31) $ 1,402 $ 2,683 $ 2,098 Exercise prices of options outstanding (calculated as of December 31) $ 24.17 $ 25.00 $ 23.69 Weighted-average contractual life of outstanding options (calculated as of December 31, in years) 0.8 0.8 0.8
Fair value of options issued based on weighted-average assumptions	2018 2017 2016 Risk-free interest rates 1.89 % 1.20 % 1.06 % Expected dividend yields 3.66 % 3.70 % 4.64 % Expected life (in years) 1.45 1.45 1.42 Expected volatility 28.4 % 20.4 % 17.6 % Expected forfeiture rates 85 % 85 % 85 %

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
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, 2018 . Year Ended December 31, (Dollars in thousands, except per share data) 2018 2017 2016 Weighted Average Common Shares Weighted average Common Shares outstanding 125,219,773 119,739,216 109,861,580 Non-vested shares (1,927,648 ) (1,813,058 ) (1,289,478 ) Weighted average Common Shares - Basic 123,292,125 117,926,158 108,572,102 Weighted average Common Shares - Basic 123,292,125 117,926,158 108,572,102 Dilutive effect of non-vested shares — — 709,559 Dilutive effect of employee stock purchase plan 58,808 91,007 105,336 Weighted average Common Shares - Diluted 123,350,933 118,017,165 109,386,997 Net Income $ 69,771 $ 23,092 $ 85,571 Dividends paid on nonvested share-based awards (2,320 ) (2,149 ) — Net income applicable to common stockholders $ 67,451 $ 20,943 $ 85,571 Basic Earnings Per Common Share $ 0.55 $ 0.18 $ 0.79 Diluted Earnings Per Common Share $ 0.55 $ 0.18 $ 0.78

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of construction activity	The table below details the Company’s construction activity as of December 31, 2018 . The information included in the table below represents management’s estimates and expectations at December 31, 2018 , which are subject to change. The Company’s disclosures regarding certain projections or estimates of completion dates may not reflect actual results. December 31, 2018 (Dollars in thousands) Number of Properties Initial Occupancy Construction in Progress Balance Total Funded During the Year Total Amount Funded Estimated Remaining Fundings (unaudited) Estimated Total Investment (unaudited) Approximate Square Feet (unaudited) Construction Activity Charlotte, NC 1 Q2 2019 $ 9,586 $ 6,099 $ 9,586 2,414 $ 12,000 38,000 Seattle, WA 1 Q4 2019 23,521 21,549 23,821 40,299 64,120 151,000 Total $ 33,107 $ 27,648 $ 33,407 $ 42,713 $ 76,120 189,000
Minimum lease payments for its operating leases	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

Other Data (Tables)

Other Data (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
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, 2018 : Year Ended December 31, (Dollars in thousands) 2018 2017 2016 Net income $ 69,771 $ 23,092 $ 85,571 Reconciling items to taxable income: Depreciation and amortization 64,775 46,426 38,260 Gain or loss on disposition of depreciable assets (27,581 ) 1,570 (32,103 ) Impairments — — 121 Straight-line rent (3,049 ) (4,551 ) (7,101 ) Receivable allowances 2,470 1,680 2,067 Stock-based compensation (1,699 ) 1,855 1,301 Other 842 6,552 2,236 35,758 53,532 4,781 Taxable income (1) $ 105,529 $ 76,624 $ 90,352 Dividends paid $ 150,266 $ 142,327 $ 131,759 ______
Characterization of distributions on common stock	For the three years ended December 31, 2018 , there were no preferred shares outstanding. As such, no dividends were distributed related to preferred shares for those periods. 2018 2017 2016 Per Share % Per Share % Per Share % Common stock: Ordinary income (1) $ 0.75 62.2 % $ 0.42 34.5 % $ 0.78 65.0 % Return of capital 0.33 27.8 % 0.50 42.0 % 0.35 29.5 % Unrecaptured section 1250 gain 0.12 10.0 % 0.28 23.5 % 0.07 5.5 % Common stock distributions $ 1.20 100.0 % $ 1.20 100.0 % $ 1.20 100.0 % ______
State Income Taxes	State income tax expense and state income tax payments for the three years ended December 31, 2018 are detailed in the table below: Year Ended December 31, (Dollars in thousands) 2018 2017 2016 State income tax expense: Texas gross margins tax $ 586 $ 608 $ 562 Other — — 2 Total state income tax expense $ 586 $ 608 $ 564 State income tax payments, net of refunds and collections $ 637 $ 555 $ 544

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
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, 2018 and 2017 . December 31, 2018 December 31, 2017 (Dollars in millions) Carrying Value Fair Value Carrying Value Fair Value Notes and bonds payable (1) $ 1,346.0 $ 1,326.5 $ 1,283.9 $ 1,269.7 ______

Selected Quarterly Financial _2

Selected Quarterly Financial Data (unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Selected Quarterly Financial Information [Abstract]
Summary of quarterly financial information	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 from continuing operations $ 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 properties. Quarterly financial information for the year ended December 31, 2017 is summarized below. Quarter Ended (Dollars in thousands, except per share data) March 31 (1) June 30 (2) September 30 (3) December 31 (4) 2017 Revenues from continuing operations $ 104,644 $ 105,318 $ 107,025 $ 107,749 Net income attributable to common stockholders $ 31,845 $ 25,224 $ 3,173 $ (37,151 ) Net income attributable to common stockholders per share: Basic earnings per common share $ 0.28 $ 0.22 $ 0.02 $ (0.31 ) Diluted earnings per common share $ 0.28 $ 0.22 $ 0.02 $ (0.31 ) ______ (1) The increases in net income and amounts per share for the first quarter of 2017 are primarily attributable to gains of $23.4 million on the sale of six properties. (2) The increases in net income and amounts per share for the second quarter of 2017 are primarily attributable to gains of $16.1 million on the sale of three properties. (3) The decreases in net income and amounts per share for the third quarter of 2017 are primarily attributable to impairment charges of $5.1 million . (4) The decreases in net income and amounts per share for the fourth quarter of 2017 are primarily attributable to a loss on the extinguishment of debt of $45.0 million

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Useful lives of real estate assets and liabilities (Details)	12 Months Ended
	Dec. 31, 2018
Land improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	5 years
Land improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	39 years
Building and improvements [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	3 years 3 months 18 days
Building and improvements [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	39 years
Lease intangibles (including ground lease intangibles) [Member] | 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) [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	99 years
Intangible asset useful life	99 years
Personal property [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	2 years 9 months 18 days
Personal property [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Asset estimated useful life	20 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Components of rental income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Property operating income	$ 390,256	$ 358,009	$ 331,109
Single-tenant net lease	47,860	52,897	63,895
Straight-line rent	4,281	6,072	7,201
Rental income	$ 442,397	$ 416,978	$ 402,205

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Components of other operating income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Other Operating Income [Abstract]
Other operating	$ 7,992	$ 7,759	$ 9,750

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Revenue Recognition (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Other operating	$ 7,992	$ 7,759	$ 9,750
Parking Income [Member]
Disaggregation of Revenue [Line Items]
Other operating	6,930	6,611	6,121
Property Lease Guaranty Income [Member]
Disaggregation of Revenue [Line Items]
Other operating	675	726	3,058
Management Fee Income [Member]
Disaggregation of Revenue [Line Items]
Other operating	273	308	402
Miscellaneous [Member]
Disaggregation of Revenue [Line Items]
Other operating	$ 114	$ 114	$ 169

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Reclassifications (Details) - USD ($) $ in Thousands	3 Months Ended					12 Months Ended
	Dec. 31, 2018	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property operating expense			$ 157,252			$ 170,506	$ 157,252	$ 146,529
Bad debt, net			159			60	159	(21)
Gains on sales of properties	$ 10,800	$ 27,700	39,524	$ 16,100	$ 23,400	41,665	39,524	41,044
Impairments			(5,385)				(5,385)	(121)
INCOME FROM CONTINUING OPERATIONS			23,092			$ 67,451	$ 20,943	85,571
Loss from discontinued operations			0					0
Impairments of real estate assets			0					0
Gain on sales of properties			0					0
LOSS FROM DISCONTINUED OPERATIONS			0					0
As Previously Reported
Property, Plant and Equipment [Line Items]
Property operating expense			157,233					146,458
Bad debt, net			169					(21)
Gains on sales of properties			39,519					41,038
Impairments			(5,385)					0
INCOME FROM CONTINUING OPERATIONS			23,096					85,756
Loss from discontinued operations			(9)					(71)
Impairments of real estate assets			0					(121)
Gain on sales of properties			5					7
LOSS FROM DISCONTINUED OPERATIONS			$ (4)					$ (185)

Summary of Significant Accoun_9

Summary of Significant Accounting Policies - Narrative (Details) ft² in Millions	12 Months Ended
	Dec. 31, 2018USD ($)ft²land_parcelreporting_unitstateproperty	Dec. 31, 2017USD ($)land_parcelproperty	Dec. 31, 2016USD ($)property
Business Overview [Abstract]
Gross investment, amount, total	$ 4,000,000,000
Real estate properties and mortgages | property	199
Number of owned real estate properties | property	199
Number of states that the Company owns real estate in | state	27
Square footage of owned real estate properties | ft²	14.8
Approximate square feet for which Nationwide property management services provided by company | ft²	11.2
Segment Reporting [Abstract]
Number of Reporting Units | reporting_unit	1
Real Estate Properties [Abstract]
Total real estate properties	$ 3,974,071,000	$ 3,838,638,000
Elimination of real estate lease intangibles against accumulated depreciation	23,200,000	16,600,000
Depreciation	$ 143,800,000	$ 129,400,000	$ 116,500,000
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	6
Land held for development	$ 24,600,000	$ 20,100,000
Goodwill and Intangible Assets [Abstract]
Goodwill impairment loss	0	0
Goodwill	$ 3,500,000	3,487,000
Incentive Plans [Abstract]
Discount on market price on the date of grant	85.00%
Discount on market price on the date of exercise	85.00%
Expiration date	27 months
General and administrative	$ 34,511,000	32,992,000	31,309,000
Rental Income [Abstract]
Operating expense recoveries included in income from continuing operations	$ 81,100,000	$ 73,400,000	$ 66,000,000
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	2
Federal Income Taxes [Abstract]
Percentage of distribution of taxable income for qualify as REIT	90.00%
Maximum [Member]
Real Estate Properties [Line Items]
Lessee, Operating Lease, Term of Contract	99 years
Minimum [Member]
Real Estate Properties [Line Items]
Lessee, Operating Lease, Term of Contract	40 years
Weighted Average [Member]
Real Estate Properties [Line Items]
Lessee, Operating Lease, Term of Contract	53 years 10 months 24 days
At Market Lease Intangibles [Member]
Real Estate Properties [Abstract]
Elimination of real estate lease intangibles against accumulated depreciation	$ 9,900,000	$ 10,200,000
Employee Stock Purchase Plan [Member]
Incentive Plans [Abstract]
General and administrative	300,000	200,000	$ 200,000
Tenant and Capital Improvements [Member]
Real Estate Properties [Abstract]
Fully depreciated tenant and capital improvements eliminated against accumulated depreciation	500,000	2,600,000
Forward Starting Interest Rate Swap [Member]
Derivative Instrument Detail [Abstract]
Accumulated other comprehensive income (loss), net of tax	$ 900,000	$ 1,300,000

Summary of Significant Accou_10

Summary of Significant Accounting Policies - Impact of new accounting pronouncements (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Rental income									$ 442,397	$ 416,978	$ 402,205
Other operating									7,992	7,759	9,750
Revenues	$ 113,168	$ 113,462	$ 111,634	$ 112,124	$ 107,749	$ 107,025	$ 105,318	$ 104,644	450,389	424,737	411,955
Interest and other income, net									537	658	51
Income from continuing operations									$ 69,771	23,092	85,571
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Rental income										422,852	407,481
Other operating										1,647	4,149
Revenues										424,499	411,630
Interest and other income, net										896	375
Income from continuing operations										$ 23,092	$ 85,571
Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, discount rate (percent)	2.90%								2.90%
Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease, discount rate (percent)	6.20%								6.20%
Subsequent Event [Member] | Minimum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Present value of lease payments												$ 90,000
Lease liability												90,000
Subsequent Event [Member] | Maximum [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Present value of lease payments												100,000
Lease liability												$ 100,000

Property Investments (Details)

Property Investments (Details) $ in Thousands	Dec. 31, 2018USD ($)property	Dec. 31, 2017USD ($)
Summary of Company's investment
Number of facilities | property	199
Number of real estate investments | property	199
Land	$ 254,853
Buildings, Improvements,and Lease Intangibles	3,675,415	$ 3,601,460
Buildings, Improvements, and Lease Intangibles, including Construction in Progress	3,708,522
Personal Property	10,696	10,314
Total real estate properties	3,974,071	3,838,638
Accumulated Depreciation	(1,015,174)	$ (897,430)
Total real estate investments	3,974,071
Wholly Owned Properties [Member]
Summary of Company's investment
Accumulated Depreciation	$ (1,015,174)
Land Held for Development [Member]
Summary of Company's investment
Number of facilities | property	0
Land	$ 24,647
Buildings, Improvements,and Lease Intangibles	0
Personal Property	0
Total real estate properties	24,647
Accumulated Depreciation	(393)
Construction in Progress [Member]
Summary of Company's investment
Land	0
Buildings, Improvements,and Lease Intangibles	33,107
Personal Property	0
Total real estate properties	33,107
Accumulated Depreciation	$ 0
Corporate Property [Member]
Summary of Company's investment
Number of facilities | property	0
Land	$ 0
Buildings, Improvements,and Lease Intangibles
Personal Property	5,500
Total real estate properties	5,500
Accumulated Depreciation	$ (4,467)
Medical office/outpatient [Member]
Summary of Company's investment
Number of facilities | property	199
Land	$ 230,206
Buildings, Improvements,and Lease Intangibles	3,675,415
Personal Property	5,196
Total real estate properties	3,910,817
Accumulated Depreciation	$ (1,010,314)
Medical office/outpatient [Member] | Dallas, Texas [Member]
Summary of Company's investment
Number of facilities | property	25
Land	$ 16,911
Buildings, Improvements,and Lease Intangibles	464,077
Personal Property	430
Total real estate properties	481,418
Accumulated Depreciation	$ (166,980)
Medical office/outpatient [Member] | Washington [Member]
Summary of Company's investment
Number of facilities | property	19
Land	$ 28,867
Buildings, Improvements,and Lease Intangibles	438,880
Personal Property	419
Total real estate properties	468,166
Accumulated Depreciation	$ (69,148)
Medical office/outpatient [Member] | Nashville, Tennessee [Member]
Summary of Company's investment
Number of facilities | property	6
Land	$ 20,053
Buildings, Improvements,and Lease Intangibles	176,257
Personal Property	1,041
Total real estate properties	197,351
Accumulated Depreciation	$ (53,052)
Medical office/outpatient [Member] | Georgia [Member]
Summary of Company's investment
Number of facilities | property	8
Land	$ 1,015
Buildings, Improvements,and Lease Intangibles	189,167
Personal Property	37
Total real estate properties	190,219
Accumulated Depreciation	$ (11,547)
Medical office/outpatient [Member] | Los Angeles, California [Member]
Summary of Company's investment
Number of facilities | property	12
Land	$ 27,709
Buildings, Improvements,and Lease Intangibles	157,496
Personal Property	316
Total real estate properties	185,521
Accumulated Depreciation	$ (87,678)
Medical office/outpatient [Member] | North Carolina [Member]
Summary of Company's investment
Number of facilities | property	16
Land	$ 4,200
Buildings, Improvements,and Lease Intangibles	162,922
Personal Property	99
Total real estate properties	167,221
Accumulated Depreciation	$ (60,389)
Medical office/outpatient [Member] | Colorado [Member]
Summary of Company's investment
Number of facilities | property	9
Land	$ 16,514
Buildings, Improvements,and Lease Intangibles	131,760
Personal Property	273
Total real estate properties	148,547
Accumulated Depreciation	$ (20,315)
Medical office/outpatient [Member] | Virginia [Member]
Summary of Company's investment
Number of facilities | property	7
Land	$ 0
Buildings, Improvements,and Lease Intangibles	147,809
Personal Property	106
Total real estate properties	147,915
Accumulated Depreciation	$ (38,288)
Medical office/outpatient [Member] | Hawaii [Member]
Summary of Company's investment
Number of facilities | property	3
Land	$ 8,327
Buildings, Improvements,and Lease Intangibles	134,037
Personal Property	159
Total real estate properties	142,523
Accumulated Depreciation	$ (34,703)
Medical office/outpatient [Member] | Iowa [Member]
Summary of Company's investment
Number of facilities | property	7
Land	$ 12,665
Buildings, Improvements,and Lease Intangibles	127,063
Personal Property	99
Total real estate properties	139,827
Accumulated Depreciation	$ (30,376)
Medical office/outpatient [Member] | Houston, Texas [Member]
Summary of Company's investment
Number of facilities | property	8
Land	$ 13,672
Buildings, Improvements,and Lease Intangibles	118,918
Personal Property	77
Total real estate properties	132,667
Accumulated Depreciation	$ (39,195)
Medical office/outpatient [Member] | Oklahoma [Member]
Summary of Company's investment
Number of facilities | property	3
Land	$ 9,427
Buildings, Improvements,and Lease Intangibles	111,452
Personal Property	10
Total real estate properties	120,889
Accumulated Depreciation	$ (14,751)
Medical office/outpatient [Member] | San Francisco, California [Member]
Summary of Company's investment
Number of facilities | property	3
Land	$ 14,054
Buildings, Improvements,and Lease Intangibles	105,611
Personal Property	43
Total real estate properties	119,708
Accumulated Depreciation	$ (15,539)
Medical office/outpatient [Member] | Missouri [Member]
Summary of Company's investment
Number of facilities | property	1
Land	$ 1,989
Buildings, Improvements,and Lease Intangibles	109,304
Personal Property	0
Total real estate properties	111,293
Accumulated Depreciation	$ (14,893)
Medical office/outpatient [Member] | Austin, Texas [Member]
Summary of Company's investment
Number of facilities | property	5
Land	$ 14,236
Buildings, Improvements,and Lease Intangibles	91,816
Personal Property	119
Total real estate properties	106,171
Accumulated Depreciation	$ (20,766)
Medical office/outpatient [Member] | Washington, D.C. [Member]
Summary of Company's investment
Number of facilities | property	4
Land	$ 0
Buildings, Improvements,and Lease Intangibles	101,186
Personal Property	8
Total real estate properties	101,194
Accumulated Depreciation	$ (20,701)
Medical office/outpatient [Member] | Memphis, Tennessee [Member]
Summary of Company's investment
Number of facilities | property	7
Land	$ 5,241
Buildings, Improvements,and Lease Intangibles	90,966
Personal Property	191
Total real estate properties	96,398
Accumulated Depreciation	$ (35,109)
Medical office/outpatient [Member] | San Antonio, Texas [Member]
Summary of Company's investment
Number of facilities | property	7
Land	$ 6,647
Buildings, Improvements,and Lease Intangibles	88,954
Personal Property	378
Total real estate properties	95,979
Accumulated Depreciation	$ (37,877)
Medical office/outpatient [Member] | Illinois [Member]
Summary of Company's investment
Number of facilities | property	3
Land	$ 5,859
Buildings, Improvements,and Lease Intangibles	86,068
Personal Property	201
Total real estate properties	92,128
Accumulated Depreciation	$ (19,372)
Medical office/outpatient [Member] | Indiana [Member]
Summary of Company's investment
Number of facilities | property	3
Land	$ 3,299
Buildings, Improvements,and Lease Intangibles	72,360
Personal Property	0
Total real estate properties	75,659
Accumulated Depreciation	$ (21,299)
Medical office/outpatient [Member] | Minnesota [Member]
Summary of Company's investment
Number of facilities | property	4
Land	$ 2,090
Buildings, Improvements,and Lease Intangibles	61,761
Personal Property	0
Total real estate properties	63,851
Accumulated Depreciation	$ (7,750)
Medical office/outpatient [Member] | Other (20 markets) [Member]
Summary of Company's investment
Number of facilities | property	39
Land	$ 17,431
Buildings, Improvements,and Lease Intangibles	507,551
Personal Property	1,190
Total real estate properties	526,172
Accumulated Depreciation	$ (190,586)

Property Investments (Details T

Property Investments (Details Textual) $ in Billions	Dec. 31, 2018USD ($)property
Real Estate Investment Property, Net [Abstract]
Investment in real estate properties and mortgage notes | $	$ 4
Number of real estate investments | property	199

Real Estate Leases (Details)

Real Estate Leases (Details) $ in Thousands	Dec. 31, 2018USD ($)
Leases [Abstract]
2,019	$ 326,441
2,020	279,211
2,021	235,660
2,022	201,072
2,023	163,978
2024 and thereafter	476,673
Total	$ 1,683,035

Real Estate Leases - Narrative

Real Estate Leases - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)renewal_option
Leases [Abstract]
Approximate Investment in real estate properties subject to outstanding contractual option to purchase | $	$ 117.1
Number of exercisable purchase options | renewal_option	5

Acquisitions, Dispositions an_3

Acquisitions, Dispositions and Mortgage Repayments - Acquisitions (Details) $ in Millions	Dec. 21, 2018USD ($)	Dec. 20, 2018USD ($)	Dec. 19, 2018USD ($)ft²	Dec. 14, 2018USD ($)ft²	Aug. 24, 2018USD ($)ft²	Jun. 29, 2018USD ($)aft²	May 21, 2018USD ($)ft²	May 18, 2018USD ($)ft²	May 04, 2018USD ($)ft²	May 03, 2018USD ($)	Dec. 21, 2017USD ($)ft²	Dec. 18, 2017USD ($)ft²Garage	Dec. 13, 2017USD ($)ft²	Nov. 01, 2017USD ($)ft²	Jul. 31, 2017USD ($)ft²	Jun. 16, 2017USD ($)	Jun. 13, 2017USD ($)ft²	Jun. 12, 2017USD ($)ft²	Mar. 31, 2017USD ($)	Mar. 07, 2017USD ($)	Mar. 06, 2017USD ($)ft²	Dec. 31, 2018USD ($)ft²	Dec. 31, 2017USD ($)ft²	Sep. 30, 2017USD ($)
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Net Real Estate Investment																						$ 54.5	$ 78.2
Gain on disposition of property																						39.8	34.4
Real estate acquisitions [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Purchase Price																						111.5	327.2
Mortgage Notes Payable Assumed																						(8)	(45.8)
Cash Consideration																						103.1	283.1
Real Estate																						112.4	322.6
Other																						$ (1.2)	$ 6.3
Square Footage | ft²																						511,422	877,873
Fair value adjustments on mortgage notes payable assumed																						$ (0.1)	$ 0.6
Real estate acquisitions [Member] | Washington [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired						Jun. 29, 2018				May 4, 2018		Dec. 18, 2017		Nov. 1, 2017
Purchase Price						$ 26.2			$ 7.8			$ 8.8		$ 12.7
Mortgage Notes Payable Assumed						0				$ 0		0		0
Cash Consideration						26.2			7.8			8.8		12.6
Real Estate						26.7			7.8			9		12.8
Other						$ (0.5)			$ 0			$ (0.2)		$ (0.2)
Square Footage | ft²						86,942			13,314			32,828		26,345
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					$ 4.1			$ 12.1
Mortgage Notes Payable Assumed					0			(8)
Cash Consideration					4.2			3.8
Real Estate					4.2			12.1
Other					$ 0			$ (0.2)
Square Footage | ft²					17,084			93,992
Real estate acquisitions [Member] | Oklahoma [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired							May 21, 2018
Purchase Price							$ 11.4
Mortgage Notes Payable Assumed							0
Cash Consideration							11.4
Real Estate							11.5
Other							$ (0.1)
Square Footage | ft²							82,647
Real estate acquisitions [Member] | Tennessee [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired				Dec. 4, 2018
Purchase Price				$ 31.9
Mortgage Notes Payable Assumed				0
Cash Consideration				32
Real Estate				32
Other				$ 0
Square Footage | ft²				108,691
Real estate acquisitions [Member] | Illinois [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired			Dec. 19, 2018									Dec. 18, 2017
Purchase Price			$ 5.1									$ 28.7
Mortgage Notes Payable Assumed			0									0
Cash Consideration			4.9									27.7
Real Estate			5.1									28.5
Other			$ (0.2)									$ (0.8)
Square Footage | ft²			14,883									99,526
Real estate acquisitions [Member] | Minnesota [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired																					Mar. 6, 2017
Purchase Price																					$ 13.5
Mortgage Notes Payable Assumed																					0
Cash Consideration																					13.5
Real Estate																					13.3
Other																					$ 0.2
Square Footage | ft²																					34,608
Real estate acquisitions [Member] | San Francisco, California [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired																		Jun. 12, 2017
Purchase Price																		$ 26.8
Mortgage Notes Payable Assumed																		0
Cash Consideration																		26.8
Real Estate																		26.8
Other																		$ 0
Square Footage | ft²																		75,649
Real estate acquisitions [Member] | Washington, D.C. [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired																	Jun. 13, 2017
Purchase Price																	$ 24
Mortgage Notes Payable Assumed																	(12.1)
Cash Consideration																	12.5
Real Estate																	24.8
Other																	$ (0.2)
Square Footage | ft²																	62,379
Real estate acquisitions [Member] | Los Angeles, California [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired															Jul. 31, 2017
Purchase Price															$ 16.3
Mortgage Notes Payable Assumed															0
Cash Consideration															16.7
Real Estate															16.9
Other															$ (0.2)
Square Footage | ft²															42,780
Real estate acquisitions [Member] | Texas [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired											Dec. 21, 2017
Purchase Price											$ 2.5
Mortgage Notes Payable Assumed											0
Cash Consideration											2.5
Real Estate											2.5
Other											$ 0
Square Footage | ft²											7,972
Property ownership percentage											69.40%
Real Estate Acquisition One [Member] | Georgia [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired												Dec. 18, 2017	Dec. 13, 2017	Nov. 1, 2017
Purchase Price												$ 26.3	$ 25.8	$ 25.5
Mortgage Notes Payable Assumed												(11.8)	(10.5)	0
Cash Consideration												14.5	15.3	25.5
Real Estate												24.6	22	26.3
Other												$ 1.7	$ 3.8	$ (0.8)
Square Footage | ft²												66,984	59,427	76,944
Number of parking garages | Garage												2
Real Estate Acquisition Two [Member] | Georgia [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired												Dec. 18, 2017	Dec. 13, 2017	Nov. 1, 2017
Purchase Price												$ 14.2	$ 15.4	$ 30.3
Mortgage Notes Payable Assumed												(6.7)	(4.7)	0
Cash Consideration												7.6	10.8	30.7
Real Estate												14.5	15.7	30.7
Other												$ (0.2)	$ (0.2)	$ 0
Square Footage | ft²												40,324	40,171	74,024
Real Estate Acquisition Three [Member] | Georgia [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired														Nov. 1, 2017
Purchase Price														$ 49.7
Mortgage Notes Payable Assumed														0
Cash Consideration														50.9
Real Estate														47.5
Other														$ 3.4
Square Footage | ft²														118,180
Real Estate Acquisition Four [Member] | Georgia [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired														Nov. 1, 2017
Purchase Price														$ 6.7
Mortgage Notes Payable Assumed														0
Cash Consideration														6.7
Real Estate														6.7
Other														$ 0
Square Footage | ft²														19,732
Medical Office Building [Member] | Real estate acquisitions [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Land held for development | a						4.6
Office Building [Member] | Real estate acquisitions [Member] | Colorado [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Date Acquired								May 18, 2018
Purchase Price								$ 12.9
Mortgage Notes Payable Assumed								0
Cash Consideration								12.8
Real Estate								13
Other								$ (0.2)
Square Footage | ft²								93,869
Land held for development [Member] | Real estate acquisitions [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Land held for development | a						20.5
Appraised value of land						$ 5.8
Real estate dispositions [Member] | Colorado [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Net Real Estate Investment		$ 9.2
Gain on disposition of property		$ 6
Real estate dispositions [Member] | Tennessee [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Net Real Estate Investment	$ 8.6
Gain on disposition of property	$ 4.1
Real estate dispositions [Member] | Illinois [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Net Real Estate Investment																$ 0.4
Gain on disposition of property																$ 0
Real estate dispositions [Member] | Georgia [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Net Real Estate Investment																				$ 0.6
Gain on disposition of property																				$ 0
Real estate dispositions [Member] | Texas [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Net Real Estate Investment																								$ 46.9
Gain on disposition of property																			$ 15.8
Real estate dispositions [Member] | 812930 Parking Lots and Garages [Member]
Real Estate Acquisitions and Mortgage Note Financing [Line Items]
Net Real Estate Investment						3.9
Gain on disposition of property						$ 1.9

Acquisitions, Dispositions an_4

Acquisitions, Dispositions and Mortgage Repayments - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Building	$ 64	$ 272.1
Land	31.4	11.7
Land Improvements	2.7	1.6
Intangibles	14.2	36.7
Mortgage notes payable assumed, including fair value adjustments	(8)	(46.4)
Other assets acquired	0.2	0.4
Accounts payable, accrued liabilities and other liabilities assumed	(1.4)	(1.7)
Equity investment in joint ventures		8.7
Total cash paid	103.1	283.1
At market lease Intangibles [Member]
Business Acquisition [Line Items]
Intangibles	14.3	37.2
Below-market lease intangibles [Member]
Business Acquisition [Line Items]
Intangible liabilities	$ (0.1)	(0.9)
Intangible asset useful life	3 years 9 months 18 days
Below-market ground lease intangibles [Member]
Business Acquisition [Line Items]
Intangibles		$ 0.4
Minimum [Member] | At market lease Intangibles [Member]
Business Acquisition [Line Items]
Intangible asset useful life	1 year 3 months 18 days	2 years 1 month 6 days
Minimum [Member] | Below-market lease intangibles [Member]
Business Acquisition [Line Items]
Intangible asset useful life		8 years 6 months
Minimum [Member] | Below-market ground lease intangibles [Member]
Business Acquisition [Line Items]
Intangible asset useful life		36 years 9 months 18 days
Minimum [Member] | Building [Member]
Business Acquisition [Line Items]
Asset estimated useful life	20 years	15 years
Minimum [Member] | Land Improvements [Member]
Business Acquisition [Line Items]
Asset estimated useful life	5 years	5 years
Maximum [Member] | At market lease Intangibles [Member]
Business Acquisition [Line Items]
Intangible asset useful life	4 years 2 months 12 days	12 years 7 months 6 days
Maximum [Member] | Below-market lease intangibles [Member]
Business Acquisition [Line Items]
Intangible asset useful life		15 years
Maximum [Member] | Below-market ground lease intangibles [Member]
Business Acquisition [Line Items]
Intangible asset useful life		99 years
Maximum [Member] | Building [Member]
Business Acquisition [Line Items]
Asset estimated useful life	30 years	37 years
Maximum [Member] | Land Improvements [Member]
Business Acquisition [Line Items]
Asset estimated useful life	13 years 6 months	12 years

Acquisitions, Dispositions an_5

Acquisitions, Dispositions and Mortgage Repayments - Dispositions (Details) $ in Thousands	Dec. 27, 2018USD ($)ft²	Dec. 21, 2018USD ($)ft²	Dec. 20, 2018USD ($)ft²	Aug. 30, 2018USD ($)ft²	Jun. 27, 2018USD ($)ft²property	Apr. 26, 2018USD ($)ft²buildingproperty	Sep. 07, 2017USD ($)ft²	Jun. 29, 2017USD ($)ft²	Jun. 16, 2017USD ($)ft²	Mar. 31, 2017USD ($)	Mar. 30, 2017USD ($)ft²	Mar. 07, 2017USD ($)ft²	Mar. 06, 2017USD ($)ft²	Dec. 31, 2017USD ($)ft²	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)ft²	Dec. 31, 2017USD ($)ft²	Dec. 31, 2016USD ($)	Sep. 30, 2017USD ($)ft²
Real Estate Dispositions [Line Items]
Sales Price														$ 122,700		$ 98,700	$ 122,700
Closing Adjustments														(3,300)		(1,900)	(3,300)
Net Proceeds																96,800	119,400
Net Real Estate Investment														78,200		54,500	78,200
Other (including receivables)														$ 6,800		2,500	6,800
Gain/ (Impairment)																$ 39,800	$ 34,400
Square Footage | ft²														416,481		806,206	416,481
Impairment of real estate														$ 5,385			$ 5,385	$ 121
Number of properties exercising purchase option | property						7
Number of single-tenant net leased buildings | building						5
Number of multi-tenant buildings | building						2
Indiana [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed													Mar. 6, 2017
Sales Price													$ 6,400
Closing Adjustments													0
Net Proceeds													6,400
Net Real Estate Investment													1,100
Other (including receivables)													0
Gain/ (Impairment)													$ 5,300
Square Footage | ft²													29,500
Virginia [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed						Apr. 26, 2018
Sales Price						$ 46,200
Closing Adjustments						0
Net Proceeds						46,200
Net Real Estate Investment						23,900
Other (including receivables)						0
Gain/ (Impairment)						$ 22,300
Square Footage | ft²						460,881
Michigan [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed					Jun. 27, 2018
Sales Price					$ 9,500
Closing Adjustments					(700)
Net Proceeds					8,800
Net Real Estate Investment					3,400
Other (including receivables)					0
Gain/ (Impairment)					$ 5,400
Square Footage | ft²					121,672
Forfeited earnest money					$ 500
Number of properties exercising purchase option | property					5
Georgia [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed												Mar. 7, 2017
Sales Price												$ 600
Closing Adjustments												0
Net Proceeds												600
Net Real Estate Investment												600
Other (including receivables)												0
Gain/ (Impairment)												$ 0
Square Footage | ft²												12,000
Nevada [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed											Mar. 30, 2017
Sales Price											$ 5,500
Closing Adjustments											(700)
Net Proceeds											4,800
Net Real Estate Investment											2,200
Other (including receivables)											300
Gain/ (Impairment)											$ 2,300
Square Footage | ft²											18,147
Texas [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed										Mar. 31, 2017
Sales Price																			$ 69,500
Closing Adjustments																			(1,600)
Net Proceeds										$ 67,900
Net Real Estate Investment																			46,900
Other (including receivables)																			$ 5,200
Gain/ (Impairment)										$ 15,800
Square Footage | ft²																			169,722
Illinois [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed									Jun. 16, 2017
Sales Price									$ 500
Closing Adjustments									(100)
Net Proceeds									400
Net Real Estate Investment									400
Other (including receivables)									0
Gain/ (Impairment)									$ 0
Square Footage | ft²									5,100
Impairment of real estate															$ 300
San Antonio, Texas [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed								Jun. 29, 2017
Sales Price								$ 14,500
Closing Adjustments								(200)
Net Proceeds								14,300
Net Real Estate Investment								5,100
Other (including receivables)								900
Gain/ (Impairment)								$ 8,300
Square Footage | ft²								39,786
Oregon [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed								Jun. 29, 2017
Sales Price								$ 23,200
Closing Adjustments								(600)
Net Proceeds								22,600
Net Real Estate Investment								14,500
Other (including receivables)								300
Gain/ (Impairment)								$ 7,800
Square Footage | ft²								62,246
Missouri [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed				Aug. 30, 2018			Sep. 7, 2017
Sales Price				$ 9,800			$ 2,500
Closing Adjustments				(500)			(100)
Net Proceeds				9,300			2,400
Net Real Estate Investment				7,500			7,400
Other (including receivables)				500			100
Gain/ (Impairment)				$ 1,300			$ (5,100)
Square Footage | ft²				70,893			79,980
Tennessee [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed		Dec. 21, 2018
Sales Price		$ 13,300
Closing Adjustments		(200)
Net Proceeds		13,100
Net Real Estate Investment		8,600
Other (including receivables)		400
Gain/ (Impairment)		$ 4,100
Square Footage | ft²		81,382
Arizona [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed	Dec. 27, 2018
Sales Price	$ 3,000
Closing Adjustments	(200)
Net Proceeds	2,800
Net Real Estate Investment	1,900
Other (including receivables)	200
Gain/ (Impairment)	$ 700
Square Footage | ft²	37,310
Colorado [Member] | Real estate dispositions [Member]
Real Estate Dispositions [Line Items]
Date Disposed			Dec. 20, 2018
Sales Price			$ 16,900
Closing Adjustments			(300)
Net Proceeds			16,600
Net Real Estate Investment			9,200
Other (including receivables)			1,400
Gain/ (Impairment)			$ 6,000
Square Footage | ft²			34,068

Held for Sale (Details)

Held for Sale (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Balance Sheet data (as of the period ended):
Land	$ 230,206	$ 201,283
Buildings, improvements and lease intangibles	3,675,415	3,601,460
Personal property	10,696	10,314
Total real estate properties	3,974,071	3,838,638
Less accumulated depreciation	(1,015,174)	(897,430)
Total real estate properties, net	2,958,897	2,941,208
Other assets, net	214,697	213,015
Assets held for sale, net	9,272	33,147
Liabilities of properties held for sale	587	93
Discontinued Operations [Member]
Balance Sheet data (as of the period ended):
Land	1,125	4,636
Buildings, improvements and lease intangibles	18,231	63,654
Personal property	0	82
Total real estate properties	19,356	68,372
Less accumulated depreciation	(10,657)	(35,790)
Total real estate properties, net	8,699	32,582
Other assets, net	573	565
Assets held for sale, net	9,272	33,147
Accounts payable and accrued liabilities	450	38
Other liabilities	137	55
Liabilities of properties held for sale	$ 587	$ 93

Held for Sale (Details Textual)

Held for Sale (Details Textual) - property	Dec. 31, 2018	Dec. 31, 2017
Discontinued Operations and Disposal Groups [Abstract]
Number of properties held for sale	1	8

Impairment Charges (Details Tex

Impairment Charges (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Impairments	$ 5.4	$ 0.1

Other Assets (Details)

Other Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Straight-line rent receivables	$ 69,500	$ 67,000
Prepaid assets	66,200	65,200
Additional long-lived assets, net	23,500	24,900
Above-market intangible assets, net	16,800	17,900
Accounts receivable	10,000	7,400
Allowance for uncollectible accounts	(300)	(300)
Ground lease modification, net	9,900	10,300
Equity investments in joint ventures	8,500	8,700
Goodwill	3,500	3,487
Project costs	2,200	2,000
Debt issuance costs, net (1)	2,200	3,500
Customer relationship intangible assets, net	1,700	1,700
Interest rate swap assets	229
Other	800	1,200
Other Assets	$ 214,697	$ 213,015

Other Assets - Unconsolidated J

Other Assets - Unconsolidated Joint Ventures (Details)	3 Months Ended			12 Months Ended
	Dec. 31, 2017building	Dec. 31, 2017USD ($)	Dec. 31, 2017Garage	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Equity Method Investments [Roll Forward]
Net LLC investments, beginning of period				$ 8,700,000
Equity income (loss) recognized during the period				4,000	$ 7,000
Owner distributions				(200,000)	0
Net LLC investments, end of period		$ 8,700,000		8,500,000	8,700,000
Parking Garages [Member]
Property, Plant and Equipment [Line Items]
Number of parking garages	2		2
Number of buildings acquired | building	3
Equity Method Investments [Roll Forward]
Net LLC investments, beginning of period				8,700,000	0
New investments during the period		8,700,000		0	8,700,000
Equity income (loss) recognized during the period				0	0
Net LLC investments, end of period		$ 8,700,000		$ 8,500,000	$ 8,700,000

Intangible Assets and Liabili_3

Intangible Assets and Liabilities - Components of intangible assets and liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Schedule of finite lived intangible assets and liabilities
Intangible assets and liabilities, gross	$ 148.3	$ 144.2
Intangible assets and liabilities, accumulated amortization	$ 60.4	47.7
Assets and liabilities, weighted avg. life (years)	16 years 6 months
Below-market lease intangibles [Member] | Other liabilities [Member]
Schedule of finite lived intangible assets and liabilities
Liabilities gross balance	$ (9.3)	(9.5)
Liabilities accumulated amortization	$ (4.1)	(3.5)
Liabilities, weighted avg. life (years)	38 years
Debt issuance costs [Member] | Notes and bonds payable [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	$ 9.3	9.3
Assets accumulated amortization	$ 2.8	1.8
Assets, weighted avg. life (years)	3 years 8 months 12 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	5.4	5.4
Assets accumulated amortization	$ 3.2	1.9
Assets, weighted avg. life (years)	1 year 7 months 6 days
Above-market lease intangibles [Member] | Other assets [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	$ 22.3	22.9
Assets accumulated amortization	$ 5.5	5
Assets, weighted avg. life (years)	59 years 7 months 6 days
Customer relationship intangibles [Member] | Other assets [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	$ 2.7	2.6
Assets accumulated amortization	$ 1	0.9
Assets, weighted avg. life (years)	24 years 7 months 6 days
At market lease Intangibles [Member] | Real estate properties [Member]
Schedule of finite lived intangible assets and liabilities
Assets gross balance	$ 114.4	110
Assets accumulated amortization	$ 52	$ 41.6
Assets, weighted avg. life (years)	4 years 9 months 18 days

Intangible Assets and Liabili_4

Intangible Assets and Liabilities - Expected future amortization expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Intangible amortization expense	$ 23.2	$ 16.6
Future Amortization of Intangibles, Net [Abstract]
2,019	22.1
2,020	15.5
2,021	9.6
2,022	7.3
2,023	$ 4.6

Notes and Bonds Payable (Detail

Notes and Bonds Payable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 11, 2017	Apr. 24, 2015	Mar. 26, 2013
Debt Instrument [Line Items]
Notes and bonds payable	$ 1,345,984	$ 1,283,880
Line of Credit [Member] | Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Notes and bonds payable	262,000	189,000
Medium-term Notes [Member] | Term Loan due 2022 [Member]
Debt Instrument [Line Items]
Notes and bonds payable	$ 149,183	148,994
Contractual interest rates, basis spread on variable rate	1.10%
Senior Notes [Member] | Senior Notes due 2023 [Member]
Debt Instrument [Line Items]
Notes and bonds payable	$ 248,117	247,703
Contractual interest rates	3.75%				3.75%
Senior Notes [Member] | Senior Notes due 2025 [Member]
Debt Instrument [Line Items]
Notes and bonds payable	$ 248,278	248,044
Contractual interest rates	3.88%			3.875%
Senior Notes [Member] | Senior Notes due 2028 [Member]
Debt Instrument [Line Items]
Notes and bonds payable	$ 295,198	294,757
Contractual interest rates	3.63%		3.625%
Mortgage Notes [Member] | Mortgage notes payable [Member]
Debt Instrument [Line Items]
Notes and bonds payable	$ 143,208	$ 155,382
LIBOR [Member] | Line of Credit [Member] | Unsecured Credit Facility [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate	1.00%
LIBOR [Member] | Medium-term Notes [Member] | Term Loan due 2022 [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate	1.10%
Minimum [Member] | Medium-term Notes [Member] | Term Loan due 2022 [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate	0.90%
Minimum [Member] | Mortgage Notes [Member]
Debt Instrument [Line Items]
Contractual interest rates	3.30%
Minimum [Member] | Mortgage Notes [Member] | Mortgage notes payable [Member]
Debt Instrument [Line Items]
Contractual interest rates	3.31%
Maximum [Member] | Medium-term Notes [Member] | Term Loan due 2022 [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate	1.75%
Maximum [Member] | Mortgage Notes [Member]
Debt Instrument [Line Items]
Contractual interest rates	6.90%
Maximum [Member] | Mortgage Notes [Member] | Mortgage notes payable [Member]
Debt Instrument [Line Items]
Contractual interest rates	6.88%

Notes and Bonds Payable - Narra

Notes and Bonds Payable - Narrative (Details)	Jul. 29, 2016extension_option	Jul. 05, 2016USD ($)	Apr. 24, 2015USD ($)swap_agreement	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)swap_agreement	Dec. 31, 2016USD ($)swap_agreement	Jan. 30, 2018USD ($)swap_agreement	Dec. 20, 2017USD ($)swap_agreement	Dec. 18, 2017Lender	Dec. 11, 2017USD ($)	Feb. 28, 2014USD ($)Lender	Mar. 26, 2013USD ($)	Oct. 14, 2011USD ($)
Debt Instrument [Line Items]
Number of interest rate swaps | swap_agreement					2
Unsecured term loan outstanding				$ 1,355,115,000
Number of forward starting swaps | swap_agreement						4
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	0.075%
Facility fee on the aggregate amount of commitments				0.20%
Amount outstanding under Unsecured Credit Facility				$ 262,000,000
Weighted average interest rate (LOC)				3.50%
Remaining borrowing capacity				$ 438,000,000
Line of Credit [Member] | Unsecured Credit Facility [Member] | Minimum [Member]
Debt Instrument [Line Items]
Facility fee on the aggregate amount of commitments				0.13%
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				1.00%
Contractual interest rates, basis spread on variable rate				1.00%
Line of Credit [Member] | Unsecured Credit Facility [Member] | LIBOR [Member] | Minimum [Member]
Debt Instrument [Line Items]
Percentage of interest in addition to LIBOR				0.83%
Line of Credit [Member] | Unsecured Credit Facility [Member] | LIBOR [Member] | Maximum [Member]
Debt Instrument [Line Items]
Percentage of interest in addition to LIBOR				1.55%
Medium-term Notes [Member] | Term Loan due 2022 [Member]
Debt Instrument [Line Items]
Senior notes face value				$ 150,000,000	$ 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				1.10%
Number of interest rate swaps | swap_agreement							2	2
Derivative notional amount							$ 50,000,000
Derivative, fixed interest rate							2.46%
Unsecured term loan outstanding				$ 150,000,000
Interest rate yielded per annum upon issuance				3.53%
Amortization of debt issuance costs				$ 200,000	200,000	$ 200,000
Medium-term Notes [Member] | Term Loan due 2022 [Member] | Interest Rate Swap [Member]
Debt Instrument [Line Items]
Derivative notional amount								$ 25,000,000
Derivative, fixed interest rate								2.18%
Medium-term Notes [Member] | Term Loan due 2022 [Member] | Minimum [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate				0.90%
Medium-term Notes [Member] | Term Loan due 2022 [Member] | Maximum [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate				1.75%
Medium-term Notes [Member] | Term Loan due 2022 [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Contractual interest rates, basis spread on variable rate				1.10%
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
Interest rate on senior notes				3.75%								3.75%
Unaccreted discount				$ 974,000	1,178,000							$ 2,100,000
Deferred finance costs, gross												$ 2,100,000
Interest rate yielded per annum upon issuance												3.95%
Amount of amortization included in interest expense on the Company's consolidated Statements of operations				200,000	200,000	200,000
Amortization of debt issuance costs				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
Interest rate on senior notes			3.875%	3.88%
Unaccreted discount			$ 200,000	$ 141,000	160,000
Deferred finance costs, gross			$ 2,300,000
Interest rate yielded per annum upon issuance			4.08%
Amortization of debt issuance costs				200,000	200,000	200,000
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
Interest rate on senior notes				3.63%						3.625%
Unaccreted discount				$ 2,319,000	2,529,000					$ 2,500,000
Deferred finance costs, gross										$ 2,700,000
Interest rate yielded per annum upon issuance										3.84%
Amount of amortization included in interest expense on the Company's consolidated Statements of operations				200,000
Amortization of debt issuance costs				$ 200,000
Mortgage Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate on senior notes				3.30%
Mortgage Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate on senior notes				6.90%
Mortgage Notes [Member] | Mortgage notes payable [Member]
Debt Instrument [Line Items]
Senior notes face value				$ 143,115,000	154,916,000
Unaccreted discount				968,000	1,332,000
Amortization of debt issuance costs				100,000	100,000	200,000
Amortization of debt discount				400,000	300,000	300,000
Amortization of debt premium				$ 800,000	$ 700,000	$ 900,000
Mortgage Notes [Member] | Mortgage notes payable [Member] | Minimum [Member]
Debt Instrument [Line Items]
Interest rate on senior notes				3.31%
Mortgage Notes [Member] | Mortgage notes payable [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest rate on senior notes				6.88%

Notes and Bonds Payable - Senio

Notes and Bonds Payable - Senior and Term Notes (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 11, 2017	Apr. 24, 2015	Feb. 28, 2014	Mar. 26, 2013
Debt Instrument [Line Items]
Issuance costs	$ (6,534,000)
Notes and bonds payable	$ 1,345,984,000	$ 1,283,880,000
Medium-term Notes [Member] | Term Loan due 2022 [Member]
Debt Instrument [Line Items]
Effective Interest rate	3.53%
Senior and term notes face value	$ 150,000,000	150,000,000			$ 200,000,000
Issuance costs	(817,000)	(1,006,000)
Notes and bonds payable	149,183,000	148,994,000
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	(974,000)	(1,178,000)				$ (2,100,000)
Issuance costs	(909,000)	(1,119,000)
Notes and bonds payable	248,117,000	247,703,000
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	(141,000)	(160,000)		$ (200,000)
Issuance costs	(1,581,000)	(1,796,000)
Notes and bonds payable	248,278,000	248,044,000
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	(2,319,000)	(2,529,000)	$ (2,500,000)
Issuance costs	(2,483,000)	(2,714,000)
Notes and bonds payable	$ 295,198,000	$ 294,757,000

Notes and Bonds Payable - Mortg

Notes and Bonds Payable - Mortgage Notes (Details) $ in Thousands	Dec. 31, 2018USD ($)mortgage_note_payablemortgage_loan	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Issuance costs	$ (6,534)
Notes and bonds payable	$ 1,345,984	$ 1,283,880
Number of Outstanding Mortgage Notes | mortgage_loan	17
Mortgage Notes [Member]
Debt Instrument [Line Items]
Issuance costs	$ (700)
Number of Outstanding Mortgage Notes | mortgage_loan	18
Mortgage notes payable [Member] | Mortgage Notes [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 143,115	154,916
Unamortized premium	1,805	2,651
Unaccreted discount	(968)	(1,332)
Issuance costs	(744)	(853)
Notes and bonds payable	143,208	$ 155,382
Municipal Government [Member] | Mortgage Notes 4.79% [Member] | Mortgage Notes [Member]
Debt Instrument [Line Items]
Mortgage notes	11,000
Unamortized premium	$ 1,000
Number of Outstanding Mortgage Notes | mortgage_note_payable	3

Notes and Bonds Payable - Detai

Notes and Bonds Payable - Details of Mortgage Notes (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)mortgage_note_payablemortgage_loan	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Number of outstanding mortgage notes | mortgage_loan	17
Mortgage Notes [Member]
Debt Instrument [Line Items]
Investment in Collateral	$ 400.2
Mortgage notes payable carrying amount	$ 143.2	$ 155.4
Number of outstanding mortgage notes | mortgage_loan	18
Mortgage Notes [Member] | Maximum [Member]
Debt Instrument [Line Items]
Contractual interest rates	6.90%
Mortgage Notes [Member] | Minimum [Member]
Debt Instrument [Line Items]
Contractual interest rates	3.30%
Mortgage Notes [Member] | Mortgage Notes 5.54% [Member] | Insurance Company [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 7.3
Effective Interest rate	5.54%
Maturity Date	2018-12
Collateral	MOB
Principal and Interest Payments	Monthly/25-yr amort.
Principal and interest amortization period	25 years
Investment in Collateral	$ 0
Mortgage notes payable carrying amount	0	6
Unemcumbered gross investment	14.4
Mortgage Notes [Member] | Mortgage Notes 5.07% [Member] | Commercial Bank [Member]
Debt Instrument [Line Items]
Mortgage notes	$ 9.5
Effective Interest rate	5.07%
Maturity Date	2019-03
Collateral	MOB
Principal and Interest Payments	Monthly/5-yr amort.
Principal and interest amortization period	5 years
Investment in Collateral	$ 0
Mortgage notes payable carrying amount	0	9.3
Unemcumbered gross investment	14.1
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	$ 27.8
Mortgage notes payable carrying amount	9	9.2
Unamortized premium	0.3
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	$ 20.2
Mortgage notes payable carrying amount	12.5	12.7
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	1.3	2
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
Mortgage notes payable carrying amount	6.2	6.5
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	$ 15.7
Mortgage notes payable carrying amount	4.6	4.8
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	$ 55.1
Mortgage notes payable carrying amount	10.3	10.5
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	10.2	10.4
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	11.2	11.5
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	$ 24.9
Mortgage notes payable carrying amount	12	12.2
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	$ 25.3
Mortgage notes payable carrying amount	7.8	0
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	$ 21.2
Mortgage notes payable carrying amount	13	13.3
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	$ 14.5
Mortgage notes payable carrying amount	6.6	6.7
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	$ 16.5
Mortgage notes payable carrying amount	8.6	8.8
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	$ 38.4
Mortgage notes payable carrying amount	10.1	10.5
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	8.8	9.6
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
Principal and Interest Payments	Semi-Annual
Investment in Collateral	$ 21
Mortgage notes payable carrying amount	11	$ 11.4
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, 2018USD ($)mortgage_loan	Dec. 31, 2017USD ($)
Long Term Debt Maturities [Line Items]
Number of outstanding mortgage notes | mortgage_loan	17
Excluded debt issuance costs	$ 2,200
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	1,355,115
Net Accretion/Amortization	(2,597)
Debt Issuance Costs (2)	(6,534)
Notes and bonds payable	$ 1,345,984	$ 1,283,880
%	100.00%
2019 [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 13,857
Net Accretion/Amortization	(250)
Debt Issuance Costs (2)	(1,067)
Notes and bonds payable	$ 12,540
%	0.90%
2020 [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 285,064
Net Accretion/Amortization	(392)
Debt Issuance Costs (2)	(1,061)
Notes and bonds payable	$ 283,611
%	21.10%
2021 [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 17,593
Net Accretion/Amortization	(326)
Debt Issuance Costs (2)	(1,046)
Notes and bonds payable	$ 16,221
%	1.20%
2022 [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 162,977
Net Accretion/Amortization	(336)
Debt Issuance Costs (2)	(1,058)
Notes and bonds payable	$ 161,583
%	12.00%
2023 [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 280,230
Net Accretion/Amortization	(183)
Debt Issuance Costs (2)	(697)
Notes and bonds payable	$ 279,350
%	20.80%
2024 and thereafter [Member]
Future contractual maturities of the Company's notes and bonds payable
Principal Maturities	$ 595,394
Net Accretion/Amortization	(1,110)
Debt Issuance Costs (2)	(1,605)
Notes and bonds payable	$ 592,679
%	44.00%

Derivative Financial Instrume_3

Derivative Financial Instruments (Details)	12 Months Ended
	Dec. 31, 2016swap_agreement	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)swap_agreement
Derivative [Line Items]
Number of forward starting swaps | swap_agreement	4
Interest rate cash flow hedge gain (loss) to be reclassified to interest expense during the next 12 months | $		$ (40,000)
Number of interest rate derivatives | swap_agreement			2
Cash Flow Hedging [Member] | Forward Starting Interest Rate Swap [Member]
Derivative [Line Items]
Notional value | $			$ 225,000,000

Derivative Financial Instrume_4

Derivative Financial Instruments - Derivative Instruments Designated as Cash Flow Hedges (Details) $ in Millions	Dec. 31, 2018USD ($)swap_agreement	Dec. 31, 2017swap_agreement
Derivative [Line Items]
Number of interest rate swaps		2
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Number of interest rate swaps	4
Derivative notional amount | $	$ 75
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap - 2017 [Member]
Derivative [Line Items]
Number of interest rate swaps	2
Derivative notional amount | $	$ 25
Cash Flow Hedging [Member] | Designated as Hedging Instrument [Member] | Interest Rate Swap - 2018 [Member]
Derivative [Line Items]
Number of interest rate swaps	2
Derivative notional amount | $	$ 50

Derivative Financial Instrume_5

Derivative Financial Instruments - Fair Value of Derivative Instruments on the Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets	$ 229
Gross Amounts of Recognized Liabilities	(68)
Interest Rate Swap - 2017 [Member] | Designated as Hedging Instrument [Member] | Other assets [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets	229
Interest Rate Swap - 2017 [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities		$ (67)
Interest Rate Swap - 2018 [Member] | Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Liabilities	(68)
Interest Rate Swap [Member] | Designated as Hedging Instrument [Member]
Derivatives, Fair Value [Line Items]
Gross Amounts of Recognized Assets	$ 161
Gross Amounts of Recognized Liabilities		$ (67)

Derivative Financial Instrume_6

Derivative Financial Instruments - Effect of Cash Flow Hedging on AOCI (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative [Line Items]
Amount of Gain/(Loss) Recognized in OCI on Derivatives	$ (27)
Amount of Loss Reclassified from OCI into Income for the Twelve Months Ended December 31,	(424)	$ (176)	$ (168)
Interest Rate Swap - 2017 [Member]
Derivative [Line Items]
Amount of Gain/(Loss) Recognized in OCI on Derivatives	246
Interest Rate Swap - 2018 [Member]
Derivative [Line Items]
Amount of Gain/(Loss) Recognized in OCI on Derivatives	(273)
Interest Rate Swap [Member]
Derivative [Line Items]
Amount of Gain/(Loss) Recognized in OCI on Derivatives	0
Interest Expense [Member]
Derivative [Line Items]
Amount of Loss Reclassified from OCI into Income for the Twelve Months Ended December 31,	424	176
Interest Expense [Member] | Interest Rate Swap - 2017 [Member]
Derivative [Line Items]
Amount of Loss Reclassified from OCI into Income for the Twelve Months Ended December 31,	51	7
Interest Expense [Member] | Interest Rate Swap - 2018 [Member]
Derivative [Line Items]
Amount of Loss Reclassified from OCI into Income for the Twelve Months Ended December 31,	204	0
Interest Expense [Member] | Interest Rate Swap [Member]
Derivative [Line Items]
Amount of Loss Reclassified from OCI into Income for the Twelve Months Ended December 31,	$ 169	$ 169

Derivative Financial Instrume_7

Derivative Financial Instruments - Offsetting Derivatives (Details) $ in Thousands	Dec. 31, 2018USD ($)
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross Amounts of Recognized Assets	$ 229
Gross Amounts Offset in the Consolidated Balance Sheets	0
Net Amounts of Assets presented in the Consolidated Balance Sheets	229
Financial Instruments	(68)
Cash Collateral	0
Net Amount	161
Gross Amounts of Recognized Assets	(68)
Gross Amounts Offset in the Consolidated Balance Sheets	0
Net Amounts of Assets presented in the Consolidated Balance Sheets	(68)
Financial Instruments	68
Cash Collateral	0
Net Amount	$ 0

Stockholders' Equity - Common s

Stockholders' Equity - Common shares (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of the beginning and ending common stock outstanding
Balance, beginning of year (shares)	125,132,000
Balance, end of year (shares)	125,279,000	125,132,000
Common Stock [Member]
Reconciliation of the beginning and ending common stock outstanding
Balance, beginning of year (shares)	125,131,593	116,416,900	101,517,009
Issuance of common stock (shares)	26,203	8,395,607	14,063,100
Non-vested stock-based awards, net of withheld shares and forfeitures (shares)	121,659	319,086	836,791
Balance, end of year (shares)	125,279,455	125,131,593	116,416,900

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details) - $ / shares	Feb. 12, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	May 02, 2017	May 01, 2017
Class of Stock [Line Items]
Dividend per share to common stockholders, paid (in dollars per share)		$ 0.3	$ 0.3	$ 0.3		$ 1.20	$ 1.20	$ 1.20
Dividends per share to common stockholders, declared (in dollars per share)					$ 0.30	$ 1.20
Common stock, authorized shares (shares)		300,000,000				300,000,000	300,000,000		300,000,000	150,000,000
Number of common shares authorized to be repurchased (shares)		3,000,000				3,000,000
Dividend Declared [Member] | Subsequent Event [Member]
Class of Stock [Line Items]
Dividends per share to common stockholders, declared (in dollars per share)	$ 0.30
Common Stock [Member]
Class of Stock [Line Items]
Issuance of common stock (shares)						26,203	8,395,607	14,063,100

Stockholders' Equity - At the M

Stockholders' Equity - At the Market Equity Offering Program (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)$ / sharesshares	Feb. 13, 2019shares	Feb. 19, 2016investment_bankshares	Feb. 17, 2016investment_bank
Class of Stock [Line Items]
Proceeds from Issuance of Common Stock | $	$ 611	$ 248,554	$ 450,503
At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Equity offering program, number of investment banks in sales agreements | investment_bank					5
Equity offering program, shares authorized to be sold (shares)					10,000,000
Issuance of common stock (shares)	0	0	4,795,601
Proceeds from Issuance of Common Stock | $	$ 0	$ 0	$ 144,600
Previous At the Market Equity Offering Program [Member]
Class of Stock [Line Items]
Equity offering program, number of investment banks in sales agreements | investment_bank						1
Minimum [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Shares issued during period (USD per share) | $ / shares			$ 28.31
Maximum [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Shares issued during period (USD per share) | $ / shares			$ 33.66
Subsequent Event [Member] | At The Market Equity Offering Program [Member]
Class of Stock [Line Items]
Number of authorized shares remaining under offering program (shares)				5,868,697

Stockholders' Equity - Accumula

Stockholders' Equity - Accumulated Other Comprehensive Income (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)swap_agreement	Dec. 31, 2016USD ($)
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Number of interest rate swaps | swap_agreement		2
Increase to accumulated other comprehensive loss	$ 27	$ 74
Period of impact on net income	10 years
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income	$ 397	102	$ 168
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	(1,299)	(1,401)
Other comprehensive loss before reclassifications	424	176
Amounts reclassified from accumulated other comprehensive income (loss)	(27)	(74)
Other comprehensive income	397	102
Balance, end of period	(902)	(1,299)	$ (1,401)
Interest Rate Swap [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Increase to accumulated other comprehensive loss	(400)
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance, beginning of period	1,300
Balance, end of period	$ 900	$ 1,300

Stockholders' Equity - Reclassi

Stockholders' Equity - Reclassifications out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest Expense	$ 52,804	$ 56,402	$ 57,351
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)	424
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	169
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	$ 255

Stock and Other Incentive Pla_3

Stock and Other Incentive Plans - Amortization of Compensation for Nonvested Shares (Details) $ in Millions	Dec. 31, 2018USD ($)
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
2,019	$ 8.6
2,020	8.1
2,021	7
2,022	4.5
2,023	2.3
2024 and thereafter	2.8
Total	$ 33.3

Stock and Other Incentive Pla_4

Stock and Other Incentive Plans (Details) - Stock Incentive Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summary of the activity under the incentive plans
Stock-based awards, beginning of year (shares)	1,907,645	1,786,497	1,092,262
Granted (shares)	273,012	413,489	885,219
Vested (shares)	(410,794)	(292,341)	(190,984)
Stock-based awards, end of year (shares)	1,769,863	1,907,645	1,786,497
Weighted-average grant date fair value of:
Stock-based awards, beginning of year (in USD per share)	$ 28.44	$ 27.18	$ 24.72
Stock-based awards granted during the year (in USD per share)	29.72	32.05	29.60
Stock-based awards vested during the year (in USD per share)	25.32	25.88	24.34
Stock-based awards, end of year (in USD per share)	$ 29.36	$ 28.44	$ 27.18
Grant date fair value of shares granted during the year	$ 8,114	$ 13,254	$ 26,204

Stock and Other Incentive Pla_5

Stock and Other Incentive Plans (Details 1) - Employee Stock Purchase Plan [Member] - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock Options Outstanding:
Options outstanding, beginning of year (shares)	318,100	316,321	340,958
Granted (shares)	203,836	206,824	198,450
Exercised (shares)	(16,716)	(32,076)	(57,924)
Forfeited (shares)	(40,897)	(40,659)	(22,081)
Expired (shares)	(135,790)	(132,310)	(143,082)
Outstanding, end of period (shares)	328,533	318,100	316,321
Exercisable, end of period (shares)	328,533	318,100	316,321
Weighted-average exercise price:
Options outstanding, beginning of year (in USD per share)	$ 25	$ 23.69	$ 20.70
Options granted during the year (in USD per share)	27.30	25.77	24.07
Options exercised during the year (in USD per share)	24.01	24.31	21.40
Options forfeited during the year (in USD per share)	24.06	25.01	23.16
Options expired during the year (in USD per share)	23.55	23.22	18.11
Options outstanding, end of year (in USD per share)	24.17	25	23.69
Weighted-average fair value of options granted during the year (calculated as of the grant date) (in USD per share)	$ 7.81	$ 6.31	$ 5.37
Intrinsic value of options exercised during the year	$ 71	$ 271	$ 634
Intrinsic value of options outstanding (calculated as of December 31)	1,402	2,683	2,098
Intrinsic value of options exercisable (calculated as of December 31)	$ 1,402	$ 2,683	$ 2,098
Exercise prices of options outstanding (calculated as of December 31) (in USD per share)	$ 24.17	$ 25	$ 23.69
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_6

Stock and Other Incentive Plans (Details 2)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair value of options issued based on weighted-average assumptions
Risk-free interest rates	1.89%	1.20%	1.06%
Expected dividend yields	3.66%	3.70%	4.64%
Expected life (in years)	1 year 5 months 12 days	1 year 5 months 12 days	1 year 5 months 1 day
Expected volatility	28.40%	20.40%	17.60%
Expected forfeiture rates	85.00%	85.00%	85.00%

Stock and Other Incentive Pla_7

Stock and Other Incentive Plans (Details Textual)

Dec. 12, 2018USD ($)executive_officershares

Dec. 11, 2017USD ($)executive_officershares

Dec. 30, 2016USD ($)shares

Dec. 16, 2016USD ($)executive_officershares

Mar. 01, 2016USD ($)shares

Feb. 16, 2016USD ($)executive_officershares

Jul. 31, 2012

Mar. 31, 2018USD ($)executive_officershares

Mar. 31, 2017USD ($)executive_officershares

Dec. 31, 2023USD ($)

Dec. 31, 2022USD ($)

Dec. 31, 2021USD ($)

Dec. 31, 2020USD ($)

Dec. 31, 2019USD ($)

Dec. 31, 2018USD ($)shares

Dec. 31, 2017USD ($)shares

Dec. 31, 2016USD ($)Awardsshares

Dec. 31, 2014

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

Executive Incentive Plan, Cash-based Award

$ 1,100,000

401(k) Plan [Abstract]

Percentage of matching contribution

3.00%

Value of matching contribution

$ 400,000

$ 400,000

$ 400,000

Discount on market price on the date of grant

85.00%

Discount on market price on the date of exercise

85.00%

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

$ 400,000

$ 800,000

$ 1,200,000

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

1,711,240

1,438,228

Number of shares authorized (shares) | shares

1,788,760

2,061,772

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

273,012

413,489

885,219

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

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

Share-based compensation expense

$ 1,700,000

$ 1,700,000

$ 100,000

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]

Award vesting period

1 year

3 years

Share-based compensation expense

$ 800,000

$ 1,000,000

Shares issued under the plan (shares) | shares

30,989

23,231

21,374

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

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

Award vesting period

10 years

Share-based compensation expense

$ 200,000

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]

Award vesting period

10 years

Share-based compensation expense

$ 600,000

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]

Award vesting period

5 years

Share-based compensation expense

$ 900,000

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]

Share-based compensation expense

$ 10,400,000

$ 9,800,000

$ 7,400,000

Withheld of common stock (shares) | shares

151,353

94,403

48,248

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

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

Value of performance based awards released

$ 1,200,000

$ 1,300,000

Shares issued under the plan (shares) | shares

43,414

41,368

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]

Share-based compensation expense

$ 1,200,000

$ 1,100,000

$ 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 1 month 6 days

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]

Share-based compensation expense

$ 5,700,000

5,000,000

4,000,000

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] | 2018 Performance Shares [Member]

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

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] | 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] | 2018 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] | 2017 Performance Shares [Member]

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

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] | Senior 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] | February 2016 Cash Incentive and Performance-based Awards [Member]

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

Granted in period

$ 5,800,000

Executive Incentive Plan [Member] | February 2016 Cash Incentive and Performance-based Awards [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] | February 2016 Cash Incentive and Performance-based Awards [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] | February 2016 Performance Shares [Member]

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

Share-based compensation expense

1,100,000

Granted in period

$ 4,700,000

Granted in period (in shares) | shares

163,788

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

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

Award vesting period

5 years

Granted in period

$ 6,300,000

Granted in period (in shares) | shares

213,639

Executive Incentive Plan [Member] | 2016 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] | 2016 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

Salary Deferral Plan [Member]

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

Share-based compensation expense

$ 1,000,000

$ 1,200,000

$ 1,200,000

Shares issued under the plan (shares) | shares

33,348

39,016

42,256

Maximum salary deferral for officers under the plan, percent

50.00%

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

591,114

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

9,487

26,031

9,575

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

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

Award vesting period

3 years

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

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

Award vesting period

5 years

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 One [Member] | Salary Deferral Plan [Member]

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

Award vesting period

3 years

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 Two [Member] | Salary Deferral Plan [Member]

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

Award vesting period

5 years

Deferral Option Three [Member]

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

Salary Deferral Plan employer matching contribution, percent

100.00%

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

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

Award vesting period

8 years

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

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

Share-based compensation expense

$ 900,000

$ 1,000,000

$ 1,000,000

$ 1,000,000

$ 1,000,000

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

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

Share-based compensation expense

$ 1,900,000

2,000,000

2,000,000

2,000,000

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

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

Share-based compensation expense

700,000

700,000

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

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

Share-based compensation expense

$ 1,200,000

$ 1,300,000

$ 1,300,000

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Weighted Average Common Shares
Weighted average Common Shares outstanding (in shares)									125,219,773	119,739,216	109,861,580
Non-vested shares (in shares)									(1,927,648)	(1,813,058)	(1,289,478)
Weighted average Common Shares - Basic (in shares)									123,292,125	117,926,158	108,572,102
Dilutive effect of non-vested shares (in shares)											709,559
Dilutive effect of employee stock purchase plan (in shares)									58,808	91,007	105,336
Weighted average Common Shares - Diluted (in shares)									123,350,933	118,017,165	109,386,997
Net Income									$ 69,771	$ 23,092	$ 85,571
Dividends paid on nonvested share-based awards									(2,320)	(2,149)
Net income applicable to common stockholders					$ 23,092				$ 67,451	$ 20,943	$ 85,571
Basic earnings per common share (dollars per share)	$ 0.13	$ 0.05	$ 0.30	$ 0.07	$ (0.31)	$ 0.02	$ 0.22	$ 0.28	$ 0.55	$ 0.18	$ 0.79
Diluted earnings per common share (dollars per share)	$ 0.13	$ 0.05	$ 0.30	$ 0.07	$ (0.31)	$ 0.02	$ 0.22	$ 0.28	$ 0.55	$ 0.18	$ 0.78

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)ft²land_parcelrenewal_optionpropertyLease	Dec. 31, 2017USD ($)ft²land_parcel	Dec. 31, 2016USD ($)
Property, Plant and Equipment [Line Items]
Approximate square feet | ft²	14,800,000
Number of land parcels held for development | land_parcel	7	6
Investment in land held for development	$ 24,600	$ 20,100
Number of ground leases | property	107
Square feet subject to ground leases | ft²	8,800,000
Ground leases, weighted average remaining term	53 years 10 months 24 days
Rental expense relating to the operating leases	$ 6,900	6,500	$ 5,800
Number of ground leases prepaid | Lease	47
Prepaid ground leases which represented rental expense	$ 500	$ 500	$ 500
Number of ground leases, excluding prepaid leases | Lease	60
First and Second Generation Leases [Member] | Tenant Improvement Allowances [Member]
Property, Plant and Equipment [Line Items]
Anticipated amount of investment	$ 29,200
Medical Office Building Expansion [Member] | North Carolina [Member]
Property, Plant and Equipment [Line Items]
Approximate square feet | ft²		38,000
Medical Office Building [Member]
Property, Plant and Equipment [Line Items]
Total amount funded	33,407
Estimated total investment	76,120
Estimated remaining fundings (unaudited)	$ 42,713
Approximate square feet | ft²	189,000
Total Funded During the Year	$ 27,648
Medical Office Building [Member] | Nashville, Tennessee [Member]
Property, Plant and Equipment [Line Items]
Total amount funded	6,100
Medical Office Building [Member] | Nashville, Tennessee [Member] | Tenant Improvement Allowances [Member]
Property, Plant and Equipment [Line Items]
Total amount funded	1,900
Medical Office Building [Member] | North Carolina [Member]
Property, Plant and Equipment [Line Items]
Total amount funded	9,586
Estimated total investment	12,000
Estimated remaining fundings (unaudited)	$ 2,414
Approximate square feet | ft²	38,000
Total Funded During the Year	$ 6,099
Medical Office Building [Member] | Washington [Member]
Property, Plant and Equipment [Line Items]
Total amount funded	23,821
Estimated total investment	64,120
Estimated remaining fundings (unaudited)	$ 40,299
Approximate square feet | ft²	151,000
Total Funded During the Year	$ 21,549
Medical Office Building [Member] | Colorado [Member]
Property, Plant and Equipment [Line Items]
Total amount funded	1,800
Approximate square feet | ft²		99,957
Medical Office Building [Member] | Colorado [Member] | Tenant Improvement Allowances [Member]
Property, Plant and Equipment [Line Items]
Total amount funded	$ 100
Minimum [Member]
Property, Plant and Equipment [Line Items]
Ground leases, initial term	50 years
Ground leases, number of renewal options | renewal_option	1
Ground leases, renewal term	75 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Ground leases, initial term	75 years
Ground leases, renewal term	100 years

Commitments and Contingencies_2

Commitments and Contingencies - Construction Activity (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)ft²property
Other Commitments [Line Items]
Number of Properties | property	199
Approximate Square Feet | ft²	14,800,000
Medical Office Building [Member]
Other Commitments [Line Items]
Construction in Progress Balance	$ 33,107
Total Funded During the Year	27,648
Total Amount Funded	33,407
Estimated Remaining Fundings (unaudited)	42,713
Estimated Total Investment (unaudited)	$ 76,120
Approximate Square Feet | ft²	189,000
North Carolina [Member] | Medical Office Building [Member]
Other Commitments [Line Items]
Number of Properties | property	1
Construction in Progress Balance	$ 9,586
Total Funded During the Year	6,099
Total Amount Funded	9,586
Estimated Remaining Fundings (unaudited)	2,414
Estimated Total Investment (unaudited)	$ 12,000
Approximate Square Feet | ft²	38,000
Washington [Member] | Medical Office Building [Member]
Other Commitments [Line Items]
Number of Properties | property	1
Construction in Progress Balance	$ 23,521
Total Funded During the Year	21,549
Total Amount Funded	23,821
Estimated Remaining Fundings (unaudited)	40,299
Estimated Total Investment (unaudited)	$ 64,120
Approximate Square Feet | ft²	151,000

Commitments and Contingencies_3

Commitments and Contingencies - Minimum lease payments (Details) $ in Thousands	Dec. 31, 2018USD ($)
Future minimum lease payments due to the Company under property operating agreements
2,019	$ 5,288
2,020	5,260
2,021	5,238
2,022	5,207
2,023	5,224
2024 and thereafter	323,533
Total	$ 349,750

Other Data (Details)

Other Data (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Net income	$ 69,771	$ 23,092	$ 85,571
Reconciling items to taxable income:
Depreciation and amortization	64,775	46,426	38,260
Gain or loss on disposition of depreciable assets	(27,581)	1,570	(32,103)
Impairments	0	0	121
Straight-line rent	(3,049)	(4,551)	(7,101)
Receivable allowances	2,470	1,680	2,067
Stock-based compensation	(1,699)	1,855	1,301
Other	842	6,552	2,236
Reconciling items to taxable income, total	35,758	53,532	4,781
Taxable income	105,529	76,624	90,352
Dividends paid	$ 150,266	$ 142,327	$ 131,759

Other Data (Details 1)

Other Data (Details 1) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Characterization of distributions on common stock
Ordinary income per share	$ 0.75	$ 0.42	$ 0.78
Return of capital per share	0.33	0.50	0.35
Unrecaptured section 1250 gain per share	0.12	0.28	0.07
Common stock distributions per share	$ 1.20	$ 1.20	$ 1.20
Ordinary income in percent of common stock distribution	62.20%	34.50%	65.00%
Return of capital in percent of common stock distribution	27.80%	42.00%	29.50%
Unrecaptured section 1250 gain in percent of common stock distribution	10.00%	23.50%	5.50%
Common stock distribution in percentage	100.00%	100.00%	100.00%

Other Data (Details 2)

Other Data (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
State income tax expense:
Texas gross margins tax	$ 586	$ 608	$ 562
Other	0	0	2
Total state income tax expense	586	608	564
State income tax payments, net of refunds and collections	$ 637	$ 555	$ 544

Other Data (Details Textual)

Other Data (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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	$ 4,000,000,000	$ 4,000,000,000	$ 3,700,000,000
Number of preferred shares outstanding (shares)	0	0	0
Dividends distributed to preferred shares	$ 0

Fair Value of Financial Instr_3

Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes and bonds payable	$ 1,346	$ 1,283.9
Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes and bonds payable	$ 1,326.5	$ 1,269.7

Selected Quarterly Financial _3

Selected Quarterly Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Summary of quarterly financial information
Revenues from continuing operations	$ 113,168	$ 113,462	$ 111,634	$ 112,124	$ 107,749	$ 107,025	$ 105,318	$ 104,644	$ 450,389	$ 424,737	$ 411,955
NET INCOME	$ 16,314	$ 6,548	$ 37,729	$ 9,180	$ (37,151)	$ 3,173	$ 25,224	$ 31,845
Net income attributable to common stockholders per share:
Basic earnings per common share (dollars per share)	$ 0.13	$ 0.05	$ 0.30	$ 0.07	$ (0.31)	$ 0.02	$ 0.22	$ 0.28	$ 0.55	$ 0.18	$ 0.79
Diluted earnings per common share (dollars per share)	$ 0.13	$ 0.05	$ 0.30	$ 0.07	$ (0.31)	$ 0.02	$ 0.22	$ 0.28	$ 0.55	$ 0.18	$ 0.78

Selected Quarterly Financial _4

Selected Quarterly Financial Data (unaudited) - Additional information (Details) $ in Thousands	3 Months Ended						12 Months Ended
	Dec. 31, 2018USD ($)property	Jun. 30, 2018USD ($)property	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)property	Mar. 31, 2017USD ($)property	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Quarterly Financial Information Disclosure [Abstract]
Gain on sales of real estate assets	$ 10,800	$ 27,700	$ 39,524		$ 16,100	$ 23,400	$ 41,665	$ 39,524	$ 41,044
Number of properties sold | property	3	12			3	6
Impairment charges				$ 5,100
Loss on extinguishment of debt			$ 45,000					$ 44,985

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, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 256	$ 148	$ 179
Charged/(Credited) to Costs and Expenses, Additions and Deductions	60	159	(21)
Charged to Other Accounts, Additions and Deductions	0	0	0
Uncollectible Accounts Written-off	65	51	10
Balance at End of Period	$ 251	$ 256	$ 148

Schedule III - Real Estate an_2

Schedule III - Real Estate and Accumulated Depreciation (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)propertyProperty	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)	Dec. 31, 2015USD ($)
Summary of real estate properties
Number of Properties | property	199
Buildings, Improvements, Lease Intangibles and CIP (1)
Gross real estate asset, Total	$ 3,993,427	$ 3,907,010	$ 3,633,993	$ 3,382,680
Accumulated depreciation	$ 1,025,831	$ 933,220	$ 843,816	$ 762,996
Medical office/outpatient [Member] | Minimum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Jan. 1, 1993
Date Constructed	Jan. 1, 1906
Medical office/outpatient [Member] | Maximum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Dec. 31, 2017
Date Constructed	Dec. 31, 2015
Inpatient [Member] | Minimum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Jan. 1, 1994
Date Constructed	Jan. 1, 1986
Inpatient [Member] | Maximum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Dec. 31, 2013
Date Constructed	Dec. 31, 2013
Other [Member] | Minimum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Jan. 1, 1993
Date Constructed	Jan. 1, 1964
Other [Member] | Maximum [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Date Acquired	Dec. 31, 2015
Date Constructed	Dec. 31, 2015
Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	200
Land (1)
Initial Investment	$ 224,504
Cost Capitalized Subsequent to Acquisition	6,827
Total	231,331
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	3,123,655
Cost Capitalized Subsequent to Acquisition	569,991
Total	3,693,646
Personal Property	5,196
Gross real estate asset, Total	3,930,173
Accumulated depreciation	1,020,971
Encumbrances	$ 143,208
Land Held for Development [Member]
Summary of real estate properties
Number of Properties | 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	393
Encumbrances	0
Construction in Progress [Member]
Buildings, Improvements, Lease Intangibles and CIP (1)
Total	33,107
Gross real estate asset, Total	$ 33,107
Corporate Property [Member]
Summary of real estate properties
Number of Properties | 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	4,467
Encumbrances	$ 0
Owned Property [Member]
Summary of real estate properties
Number of Properties | Property	200
Land (1)
Initial Investment	$ 249,151
Cost Capitalized Subsequent to Acquisition	6,827
Total	255,978
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	3,123,655
Cost Capitalized Subsequent to Acquisition	569,991
Total	3,726,753
Personal Property	10,696
Gross real estate asset, Total	3,993,427
Accumulated depreciation	1,025,831
Encumbrances	$ 143,208
Dallas, Texas [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	25
Land (1)
Initial Investment	$ 16,668
Cost Capitalized Subsequent to Acquisition	243
Total	16,911
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	345,126
Cost Capitalized Subsequent to Acquisition	118,951
Total	464,077
Personal Property	430
Gross real estate asset, Total	481,418
Accumulated depreciation	166,980
Encumbrances	$ 0
Washington [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	19
Land (1)
Initial Investment	$ 27,050
Cost Capitalized Subsequent to Acquisition	1,817
Total	28,867
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	407,491
Cost Capitalized Subsequent to Acquisition	31,389
Total	438,880
Personal Property	419
Gross real estate asset, Total	468,166
Accumulated depreciation	69,148
Encumbrances	$ 31,868
Nashville, Tennessee [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	61,196
Total	176,257
Personal Property	1,041
Gross real estate asset, Total	197,351
Accumulated depreciation	53,052
Encumbrances	$ 0
Georgia [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	8
Land (1)
Initial Investment	$ 588
Cost Capitalized Subsequent to Acquisition	427
Total	1,015
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	187,088
Cost Capitalized Subsequent to Acquisition	2,079
Total	189,167
Personal Property	37
Gross real estate asset, Total	190,219
Accumulated depreciation	11,547
Encumbrances	$ 32,597
Los Angeles, California [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	12
Land (1)
Initial Investment	$ 27,281
Cost Capitalized Subsequent to Acquisition	428
Total	27,709
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	117,144
Cost Capitalized Subsequent to Acquisition	40,352
Total	157,496
Personal Property	316
Gross real estate asset, Total	185,521
Accumulated depreciation	87,678
Encumbrances	$ 23,103
North Carolina [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	150,022
Cost Capitalized Subsequent to Acquisition	12,900
Total	162,922
Personal Property	99
Gross real estate asset, Total	167,221
Accumulated depreciation	60,389
Encumbrances	$ 0
Colorado [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	108,206
Cost Capitalized Subsequent to Acquisition	23,554
Total	131,760
Personal Property	273
Gross real estate asset, Total	148,547
Accumulated depreciation	20,315
Encumbrances	$ 7,789
Virginia [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	8,173
Total	147,809
Personal Property	106
Gross real estate asset, Total	147,915
Accumulated depreciation	38,288
Encumbrances	$ 0
Hawaii [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	40,198
Total	134,037
Personal Property	159
Gross real estate asset, Total	142,523
Accumulated depreciation	34,703
Encumbrances	$ 0
Iowa [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	116,647
Cost Capitalized Subsequent to Acquisition	10,416
Total	127,063
Personal Property	99
Gross real estate asset, Total	139,827
Accumulated depreciation	30,376
Encumbrances	$ 1,262
Houston, Texas [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	8
Land (1)
Initial Investment	$ 13,408
Cost Capitalized Subsequent to Acquisition	264
Total	13,672
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	96,894
Cost Capitalized Subsequent to Acquisition	22,024
Total	118,918
Personal Property	77
Gross real estate asset, Total	132,667
Accumulated depreciation	39,195
Encumbrances	$ 0
Oklahoma [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	3
Land (1)
Initial Investment	$ 9,077
Cost Capitalized Subsequent to Acquisition	350
Total	9,427
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	111,043
Cost Capitalized Subsequent to Acquisition	409
Total	111,452
Personal Property	10
Gross real estate asset, Total	120,889
Accumulated depreciation	14,751
Encumbrances	$ 6,225
San Francisco, California [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	11,759
Total	105,611
Personal Property	43
Gross real estate asset, Total	119,708
Accumulated depreciation	15,539
Encumbrances	$ 0
Missouri [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	14,893
Encumbrances	$ 0
Austin, Texas [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	20,840
Total	91,816
Personal Property	119
Gross real estate asset, Total	106,171
Accumulated depreciation	20,766
Encumbrances	$ 0
Washington, D.C. [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	4
Land (1)
Initial Investment	$ 0
Cost Capitalized Subsequent to Acquisition	0
Total	0
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	93,730
Cost Capitalized Subsequent to Acquisition	7,456
Total	101,186
Personal Property	8
Gross real estate asset, Total	101,194
Accumulated depreciation	20,701
Encumbrances	$ 11,980
Memphis, Tennessee [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	68,180
Cost Capitalized Subsequent to Acquisition	22,786
Total	90,966
Personal Property	191
Gross real estate asset, Total	96,398
Accumulated depreciation	35,109
Encumbrances	$ 0
San Antonio, Texas [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	7
Land (1)
Initial Investment	$ 6,617
Cost Capitalized Subsequent to Acquisition	30
Total	6,647
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	62,760
Cost Capitalized Subsequent to Acquisition	26,194
Total	88,954
Personal Property	378
Gross real estate asset, Total	95,979
Accumulated depreciation	37,877
Encumbrances	$ 0
Illinois [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	69,964
Cost Capitalized Subsequent to Acquisition	16,104
Total	86,068
Personal Property	201
Gross real estate asset, Total	92,128
Accumulated depreciation	19,372
Encumbrances	$ 0
Indiana [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	3
Land (1)
Initial Investment	$ 3,299
Cost Capitalized Subsequent to Acquisition	0
Total	3,299
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	68,994
Cost Capitalized Subsequent to Acquisition	3,366
Total	72,360
Personal Property	0
Gross real estate asset, Total	75,659
Accumulated depreciation	21,299
Encumbrances	$ 0
Minnesota [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | 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	683
Total	61,761
Personal Property	0
Gross real estate asset, Total	63,851
Accumulated depreciation	7,750
Encumbrances	$ 19,576
Other (21 MSAs) [Member] | Real Estate [Member]
Summary of real estate properties
Number of Properties | Property	40
Land (1)
Initial Investment	$ 18,098
Cost Capitalized Subsequent to Acquisition	458
Total	18,556
Buildings, Improvements, Lease Intangibles and CIP (1)
Initial Investment	436,620
Cost Capitalized Subsequent to Acquisition	89,162
Total	525,782
Personal Property	1,190
Gross real estate asset, Total	545,528
Accumulated depreciation	201,243
Encumbrances	$ 8,808

Schedule III - Real Estate an_3

Schedule III - Real Estate and Accumulated Depreciation (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Carrying Amount of Real Estate Investments [Roll Forward]
Beginning Balance, Total Property	$ 3,907,010	$ 3,633,993	$ 3,382,680
Retirement/dispositions:
Ending Balance, Total Property	3,993,427	3,907,010	3,633,993
Reconciliation of Real Estate Accumulated Depreciation [Roll Forward]
Beginning Balance, Accumulated Depreciation	933,220	843,816	762,996
Retirement/dispositions:
Ending Balance, Accumulated Depreciation	1,025,831	933,220	843,816
Real Estate [Member]
Additions during the period:
Total Property	112,591	322,616	239,265
Retirement/dispositions:
Total Property	(132,665)	(123,639)	(94,143)
Ending Balance, Total Property	3,930,173
Additions during the period:
Accumulated Depreciation	4,175	4,206	3,898
Retirement/dispositions:
Accumulated Depreciation	(69,102)	(50,683)	(44,696)
Ending Balance, Accumulated Depreciation	1,020,971
Other improvements [Member]
Additions during the period:
Total Property	74,317	59,442	70,595
Additions during the period:
Accumulated Depreciation	157,385	135,807	121,592
Land held for development [Member]
Additions during the period:
Total Property	4,525	0	0
Retirement/dispositions:
Total Property	0	0	0
Additions during the period:
Accumulated Depreciation	153	74	26
Retirement/dispositions:
Accumulated Depreciation	0	0	0
Construction in Progress [Member]
Additions during the period:
Total Property	27,649	14,598	35,596
Retirement/dispositions:
Ending Balance, Total Property	33,107
Additions during the period:
Accumulated Depreciation	$ 0	$ 0	$ 0

Schedule III - Real Estate an_4

Schedule III - Real Estate and Accumulated Depreciation (Details Textual) $ in Thousands	12 Months Ended
	Dec. 31, 2018USD ($)property	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
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	1
Gross value of assets held for sale	$ 19,400
Accumulated depreciation on real estate assets held for sale	10,700
Issuance costs	6,534
Estimated aggregate total cost of total assets for federal income tax purposes	$ 4,000,000	$ 4,000,000	$ 3,700,000
Minimum [Member] | Building and improvements [Member]
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 [Member]
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 [Member]
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 [Member]
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Asset estimated useful life	5 years
Maximum [Member] | Building and improvements [Member]
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 [Member]
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 [Member]
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 [Member]
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	$ 700
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	1,805	2,651
Unaccreted discount	968	1,332
Issuance costs	$ 744	$ 853