CoreSite Realty 10-Q1 May 202020 Q1 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
Document and Entity Information - shares	Mar. 31, 2020	Apr. 29, 2020
Document and Entity Information
Document Type	10-Q
Document Quarterly Report	true
Document Transition Report	false
Document Period End Date	Mar. 31, 2020
Entity File Number	001-34877
Entity Registrant Name	CoreSite Realty Corp
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	27-1925611
Entity Address, Address Line One	1001 17th Street, Suite 500
Entity Address, City or Town	Denver
Entity Address, State or Province	CO
Entity Address, Postal Zip Code	80202
City Area Code	866
Local Phone Number	777-2673
Title of 12(b) Security	Common Stock, $0.01 par value per share
Trading Symbol	COR
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		37,903,353
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001490892
Amendment Flag	false

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Investments in real estate:
Land	$ 94,593	$ 94,593
Buildings and improvements	2,015,530	1,989,731
Total investments in real estate	2,110,123	2,084,324
Less: Accumulated depreciation and amortization	(756,025)	(720,498)
Net investment in operating properties	1,354,098	1,363,826
Construction in progress	437,794	394,474
Net investments in real estate	1,791,892	1,758,300
Operating lease right-of-use assets, net	175,999	172,976
Cash and cash equivalents	3,307	3,048
Accounts and other receivables, net of allowance for doubtful accounts of $904 and $371 as of March 31, 2020, and December 31, 2019, respectively	24,260	21,008
Lease intangibles, net of accumulated amortization of $4,231 and $4,022 as of March 31, 2020, and December 31, 2019, respectively	3,600	3,939
Goodwill	40,646	40,646
Other assets, net	104,555	101,082
Total assets	2,144,259	2,100,999
Liabilities:
Debt, net of unamortized deferred financing costs of $8,493 and $9,098 as of March 31, 20120 and December 31, 2019, respectively	1,572,007	1,478,402
Operating lease liabilities	190,759	187,443
Accounts payable and accrued expenses	102,148	123,304
Accrued dividends and distributions	61,637	62,332
Acquired below-market lease contracts, net of accumulated amortization of $1,511 and $3,840 as of December 31, 2019, and December 31, 2018, respectively	2,462	2,511
Unearned revenue, prepaid rent and other liabilities	50,798	33,119
Total liabilities	1,979,811	1,887,111
Stockholders' equity:
Common Stock, par value $0.01, 100,000,000 shares authorized and 37,905,933 and 36,708,691 shares issued and outstanding at March 31, 2020, and December 31, 2019, respectively	374	373
Additional paid-in capital	516,133	512,324
Accumulated other comprehensive loss	(19,158)	(6,026)
Distributions in excess of net income	(376,835)	(348,509)
Total stockholders' equity	120,514	158,162
Noncontrolling interests	43,934	55,726
Total equity	164,448	213,888
Total liabilities and equity	$ 2,144,259	$ 2,100,999

CONDENSED CONSOLIDATED BALANC_2

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
CONDENSED CONSOLIDATED BALANCE SHEETS
Allowance for doubtful accounts (in dollars)	$ 904	$ 371
Accumulated amortization, lease intangibles (in dollars)	4,231	4,022
Deferred financing costs - revolving credit facility	8,493	9,098
Accumulated amortization of below-market lease	$ 1,535	$ 1,511
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common Stock, shares issued	37,905,933	37,701,042
Common Stock, shares outstanding	37,905,933	37,701,042

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Data center revenue:
Interconnection revenue	$ 20,085	$ 18,416
Total operating revenues	147,362	138,895
Operating expenses:
Property operating and maintenance	40,183	38,110
Real estate taxes and insurance	6,190	6,196
Depreciation and amortization	40,991	35,646
Sales and marketing	6,144	5,652
General and administrative	11,267	10,170
Rent	8,399	7,688
Total operating expenses	113,174	103,462
Operating income	34,188	35,433
Interest expense	(11,183)	(9,498)
Income before income taxes	23,005	25,935
Income tax (expense) benefit	(17)	(30)
Net income	22,988	25,905
Net income attributable to noncontrolling interests	5,140	6,244
Net income attributable to common shares	$ 17,848	$ 19,661
Net income per share attributable to common shares:
Basic	$ 0.48	$ 0.54
Diluted	$ 0.48	$ 0.54
Weighted average common shares outstanding
Basic	37,335,892	36,347,781
Diluted	37,504,349	36,547,065
Rental, power, and related revenue
Data center revenue:
Rental revenue	$ 124,505	$ 117,853
Office, light-industrial and other revenue
Data center revenue:
Rental revenue	$ 2,772	$ 2,626

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME
Net income	$ 22,988	$ 25,905
Other comprehensive (loss) income:
Unrealized (loss) gain on derivative contracts	(17,028)	(4,466)
Reclassification of other comprehensive income (loss) to interest expense	114	(198)
Comprehensive income	6,074	21,241
Comprehensive income attributable to noncontrolling interests	1,358	5,120
Comprehensive income attributable to CoreSite Realty Corporation	$ 4,716	$ 16,121

CONDENSED CONSOLIDATED STATEM_3

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Distributions in Excess of Net Income	Total Stockholders' Equity	Noncontrolling Interests	Total
Balance at Dec. 31, 2018	$ 363	$ 491,314	$ (2,193)	$ (246,929)	$ 242,555	$ 92,078	$ 334,633
Balance (in shares) at Dec. 31, 2018	36,708,691
Increase (Decrease) in Stockholders' Equity
Issuance of stock awards, net of forfeitures (in shares)	192,009
Exercise of stock options		17			17		17
Exercise of stock options (in shares)	1,129
Share-based compensation	$ 1	3,592			3,593		3,593
Dividends and distributions				(40,581)	(40,581)	(12,733)	(53,314)
Net income				19,661	19,661	6,244	25,905
Other comprehensive income (loss)			(3,540)		(3,540)	(1,124)	(4,664)
Balance at Mar. 31, 2019	$ 364	494,923	(5,733)	(267,849)	221,705	84,465	306,170
Balance (in shares) at Mar. 31, 2019	36,901,829
Balance at Dec. 31, 2019	$ 373	512,324	(6,026)	(348,509)	158,162	55,726	213,888
Balance (in shares) at Dec. 31, 2019	37,701,042
Increase (Decrease) in Stockholders' Equity
Redemption of noncontrolling interests		11			11	(11)
Redemption of noncontrolling interests (in shares)	2,140
Issuance of stock awards, net of forfeitures (in shares)	199,541
Exercise of stock options		73			73		73
Exercise of stock options (in shares)	3,210
Share-based compensation	$ 1	3,725			3,726		3,726
Dividends and distributions				(46,174)	(46,174)	(13,139)	(59,313)
Net income				17,848	17,848	5,140	22,988
Other comprehensive income (loss)			(13,132)		(13,132)	(3,782)	(16,914)
Balance at Mar. 31, 2020	$ 374	$ 516,133	$ (19,158)	$ (376,835)	$ 120,514	$ 43,934	$ 164,448
Balance (in shares) at Mar. 31, 2020	37,905,933

CONDENSED CONSOLIDATED STATEM_4

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 22,988	$ 25,905
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	40,991	35,646
Amortization of above/below market leases	(34)	(86)
Amortization of deferred financing costs and hedge amortization	1,029	611
Share-based compensation	3,482	3,432
Bad debt expense (recovery)	700	(27)
Changes in operating assets and liabilities:
Accounts receivable	(3,952)	(7,658)
Deferred rent receivable	(496)	1,036
Deferred leasing costs	(6,189)	(2,694)
Other assets	(2,408)	(4,519)
Accounts payable and accrued expenses	(2,579)	2,757
Unearned revenue, prepaid rent and other liabilities	726	857
Operating leases	296	643
Net cash provided by operating activities	54,554	55,903
CASH FLOWS FROM INVESTING ACTIVITIES
Tenant improvements	(1,329)	(1,046)
Real estate improvements	(85,840)	(80,795)
Net cash used in investing activities	(87,169)	(81,841)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from exercise of stock options	73	17
Proceeds from revolving credit facility	107,500	88,000
Payments on revolving credit facility	(14,500)	(8,500)
Payments of loan fees and costs	(191)
Dividends and distributions	(60,008)	(53,884)
Net cash provided by (used in) financing activities	32,874	25,633
Net change in cash and cash equivalents	259	(305)
Cash and cash equivalents, beginning of period	3,048	2,599
Cash and cash equivalents, end of period	3,307	2,294
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for interest, net of capitalized amounts	14,670	6,350
Cash paid for operating lease liabilities	6,626	6,071
NON-CASH INVESTING AND FINANCING ACTIVITY
Construction costs payable capitalized to real estate	46,739	66,123
Accrual of dividends and distributions	61,637	$ 55,109
NON-CASH OPERATING ACTIVITY
Lease liabilities arising from obtaining right-of-use assets	$ 7,646

Organization and Description of

Organization and Description of Business	3 Months Ended
Organization and Description of Business	Mar. 31, 2020
Organization and Description of Business
Organization and Description of Business	1. Organization and Description of Business CoreSite Realty Corporation (the “Company,” “we,” “us,” or “our”) was organized in the State of Maryland on February 17, 2010, and is a fully-integrated, self-administered, and self-managed real estate investment trust (“REIT”). Through our controlling interest in CoreSite, L.P. (our “Operating Partnership”), we are engaged in the business of owning, acquiring, constructing and operating data centers. As of March 31, 2020, the Company owned a 77.6% common interest in our Operating Partnership, and affiliates of The Carlyle Group and others owned a 22.4% interest in our Operating Partnership. See additional discussion in Note 10, Noncontrolling Interests – Operating Partnership.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2020
Summary of Significant Accounting Policies
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Principles of Consolidation and Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared by our management in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and in compliance with the rules and regulations of the U.S. Securities and Exchange Commission. Accordingly, these unaudited condensed consolidated financial statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of our management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included. The results of operations for the three months ended March 31, 2020, are not necessarily indicative of the expected results for the year ending December 31, 2020. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto included in our Annual Report on Form 10-K Our Operating Partnership meets the definition and criteria of a variable interest entity (“VIE”) and we are the primary beneficiary of the VIE. Our sole significant asset is the investment in our Operating Partnership, and consequently, substantially all of our assets and liabilities represent those assets and liabilities of our Operating Partnership. Our debt is an obligation of our Operating Partnership where the creditors also have recourse against the credit of the Company. Intercompany balances and transactions have been eliminated upon consolidation. Recently Adopted Accounting Pronouncements Fair Value Measurement In August 2018, the Financial Accounting Standards Board (“FASB”) issued guidance codified in Accounting Standards Update (“ASU”) 2018-13, Fair Value Measurement Intangibles – Goodwill and Other – Internal-Use Software In August 2018, the FASB issued guidance codified in ASU 2018-15, Intangibles – Goodwill and Other – Internal-Use Software Financial Instruments – Credit Losses In June 2016, the FASB issued guidance codified in ASU 2016-13, Financial Instruments – Credit Losses Codification Improvements to Topic 326, Financial Instruments – Credit Losses Recent Accounting Pronouncements Not Yet Adopted Reference Rate Reform In March 2020, the FASB issued guidance codified in ASU 2020-04, Reference Rate Reform We determined that all other recently issued accounting pronouncements will not have a material impact on our condensed consolidated financial statements or do not apply to our operations. Use of Estimates The preparation of these unaudited condensed consolidated financial statements, in conformity with GAAP, requires our management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingencies at the date of the unaudited condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. We evaluate our estimates, including those related to assessing our standalone selling prices, performance-based equity compensation plans and the carrying values of our real estate properties, goodwill, and accrued liabilities. We base our estimates on historical experience, current market conditions, and various other assumptions that we believe to be reasonable under the circumstances. Actual results may vary from those estimates and those estimates could vary under different assumptions or conditions. Investments in Real Estate Real estate investments are carried at cost less accumulated depreciation and amortization. The cost of real estate includes the purchase price of property and leasehold improvements. Expenditures for maintenance and repairs are expensed as incurred. Significant renovations and betterments that extend the economic useful lives of assets are capitalized. During land development and construction periods, we capitalize construction costs, legal fees, financing costs, real estate taxes and insurance, rent expense and internal costs of personnel performing development, if such costs are incremental and identifiable to a specific development project. Capitalization of costs begins upon commencement of development efforts and ceases when the project is ready for its intended use and held available for occupancy. Interest is capitalized during the period of development based upon applying the weighted-average borrowing rate to the actual development costs expended. Capitalized interest costs were $3.5 million and $2.6 million for the three months ended March 31, 2020, and 2019, respectively. Depreciation and amortization are calculated using the straight-line method over the following useful lives of the assets: Buildings 27 to 40 years Building improvements 1 to 10 years Leasehold improvements The shorter of the lease term or useful life of the asset Depreciation expense was $36.9 million and $32.2 million for the three months ended March 31, 2020, and 2019, respectively. Acquisition of Investment in Real Estate When accounting for business combinations and asset acquisitions, the fair value of the real estate acquired is allocated to the acquired tangible assets, consisting primarily of land, building and building improvements, and identified intangible assets and liabilities, consisting of the value of above-market and below-market leases, value of in-place leases and the value of customer relationships. The primary difference between business combinations and asset acquisitions is that asset acquisitions require cost accumulation and allocation at a relative fair value. Acquisition costs are capitalized for asset acquisitions and are expensed for business combinations. The fair value of the land and building of an acquired property is determined by valuing the property as if it were vacant, and the “as-if-vacant” fair value is then allocated to land and building based on management's determination of the fair values of these assets. Management determines the as-if-vacant fair value of a property using methods similar to those used by independent appraisers. Factors considered by management in performing these analyses include an estimate of carrying costs during the expected lease-up periods considering current market conditions and costs to execute similar leases. The fair value of intangibles related to in-place leases includes the value of lease intangibles for above-market and below-market leases, lease origination costs, and customer relationships, determined on a lease-by-lease basis. Above-market and below-market leases are valued based on the present value (using an interest rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to the in-place leases and (ii) management's estimate of market lease rates for the corresponding in-place leases, measured over a period equal to the remaining noncancelable term of the lease and, for below-market leases, over a time period equal to the initial term plus any below-market fixed rate renewal periods. Lease origination costs include estimates of costs avoided associated with leasing the property, including tenant allowances and improvements and leasing commissions. Customer relationship intangibles relate to the additional revenue opportunities expected to be generated through rental services, interconnection services, and utility services to be provided to the in-place lease tenants. The capitalized values for above and below-market lease intangibles, lease origination costs, and customer relationships are amortized over the term of the underlying leases or the expected customer relationship. Amortization related to above-market and below-market leases where the Company is the lessor is recorded as either a reduction of or an increase to rental revenue, amortization related to above-market and below-market leases where the Company is the lessee is recorded as either a reduction of or an increase to rent expense. If a lease is terminated prior to its stated expiration, all unamortized amounts relating to that lease are written off. The carrying value of intangible assets is reviewed for impairment in connection with its respective asset group whenever events or changes in circumstances indicate that the asset group may not be recoverable. An impairment loss is recognized if the carrying amount of the asset group is not recoverable and its carrying amount exceeds its estimated fair value. No impairment loss related to these intangible assets was recognized for the three months ended March 31, 2020, or 2019. The excess of the cost of an acquired business over the net of the amounts assigned to assets acquired (including identified intangible assets) and liabilities assumed is recorded as goodwill. As of March 31, 2020, and December 31, 2019, we had $40.6 million of goodwill at each date. The Company’s goodwill has an indeterminate life and is not amortized, but is tested for impairment on an annual basis, or more frequently if events or changes in circumstances indicate that the asset might be impaired. No impairment loss was recognized for the three months ended March 31, 2020, or 2019. Cash and Cash Equivalents Cash and cash equivalents include all non-restricted cash held in financial institutions and other non-restricted highly liquid short-term investments with original maturities at acquisition of three months or less. Initial Direct Costs Initial direct costs include commissions paid to third parties, including brokers, leasing and referral agents, and internal sales commissions paid to employees for successful execution of lease agreements. Initial direct costs are incremental costs that would not have been incurred if the lease agreement had not been executed. These initial direct costs are capitalized and generally amortized over the term of the related leases using the straight-line method. If a customer lease terminates prior to the expiration of its initial term, any unamortized initial direct costs related to the lease are written off to amortization expense. Amortization of initial direct costs was $3.3 million and $3.4 million for the three months ended March 31, 2020, and 2019, respectively. Initial direct costs are included within other assets in the condensed consolidated balance sheets and consisted of the following, net of amortization, as of March 31, 2020, and December 31, 2019 (in thousands): March 31, December 31, 2020 2019 Internal sales commissions $ 15,335 $ 15,064 Third party commissions 12,820 10,845 Other 436 462 Total $ 28,591 $ 26,371 Deferred Financing Costs Deferred financing costs include costs incurred in connection with obtaining debt and extending existing debt. These financing costs are capitalized and amortized on a straight-line basis, which approximates the effective-interest method, over the term of the indebtedness and the amortization is included as a component of interest expense. Depending on the type of debt instrument, deferred financing costs are reported either in other assets or as a direct deduction from the carrying amount of the related debt liabilities in our condensed consolidated balance sheets. Recoverability of Long-Lived Assets We review our long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Impairment is recognized when estimated expected future cash flows (undiscounted and without interest charges) are less than the carrying amount of the assets. The estimation of expected future net cash flows is inherently uncertain and relies, to a considerable extent, on assumptions regarding current and future economics and market conditions and the availability of capital. If, in future periods, there are changes in the estimates or assumptions incorporated into the impairment review analysis, the changes could result in an adjustment to the carrying amount of the long-lived assets. To the extent that impairment has occurred, the excess of the carrying amount of long-lived assets over its estimated fair value would be recognized as an impairment loss charged to net income. For the three months ended March 31, 2020, and 2019, no impairment of long-lived assets was recognized in the condensed consolidated financial statements. Derivative Instruments and Hedging Activities We reflect all derivative instruments at fair value as either assets or liabilities on the condensed consolidated balance sheets. For those derivative instruments that are designated and qualify as hedging instruments, we record the gain or loss on the hedging instruments as a component of accumulated other comprehensive income or loss. For derivatives that do not meet the criteria for hedge accounting, changes in fair value are immediately recognized within net income. See additional discussion in Note 8, Derivatives and Hedging Activities. Internal-Use Software We recognize internal-use software development costs based on the development stage of the project and nature of the cost. Internal and external costs incurred during the preliminary project stage are expensed as they are incurred. Internal and external costs incurred to develop internal-use software during the application development stage are capitalized. Internal and external training costs and maintenance costs during the post-implementation-operation stage are expensed as incurred. Completed projects are placed into service and amortized over the estimated useful life of the software. No impairment of internal-use software was recognized in the condensed consolidated financial statements for the three months ended March 31, 2020, and 2019. Revenue Recognition Rental, Power, and Related Revenue We derive our revenues from leases with customers for data center and office and light-industrial space. Our leases include rental revenue lease components and nonlease revenue components, such as power and tenant reimbursements. We have elected to combine all of our nonlease revenue components that have the same pattern of transfer as the related operating lease component into a single combined lease component. Our leases with customers are classified as operating leases and rental revenue is recognized on a straight-line basis over the customer lease term. Occasionally, our customer leases include options to extend or terminate the lease agreements. We do not include any of these extension or termination options in a customer’s lease term for lease classification purposes or for recognizing rental revenue unless we are reasonably certain the customer will exercise these extension or termination options. The excess of rents recognized over amounts contractually due pursuant to the underlying leases is recorded as deferred rent receivable within other assets on our condensed consolidated balance sheets. In general, we provide two power products for our data center leased space, consisting of a fixed (breakered-amperage) and a variable (sub-metered) model. Customer power arrangements are coterminous with the customer’s underlying lease and have the same pattern of transfer over the lease term and are therefore combined with lease revenue within our condensed consolidated statements of operations. For fixed power arrangements, a customer pays us a fixed monthly fee for a committed available amount of power. We recognize the fixed power revenue each month over the term of the lease. For variable power arrangements, a customer pays us variable monthly fees for the specific amount of power utilized at the current utility rates. We recognize variable power revenue each month as the uncertainty related to the consideration is resolved, as power is provided to our customers, and as our customers utilize the power. Some of our leases contain provisions under which our customers reimburse us for common area maintenance and other executory costs. These customer reimbursements are variable and are recognized in the period that the expenses are recognized. These services have the same pattern of transfer over the lease term and are also combined with lease revenue within our condensed consolidated statements of operations. Interconnection Revenue We also derive revenue from interconnection services, which are generally contracted on a month-to-month basis cancellable by us or the customer at any time. Interconnection services are accounted for as separate contracts and are not combined with lease and power arrangements. We recognize interconnection revenue each month as these services are delivered to, and utilized by, our customers. Allowance for Doubtful Accounts A provision for uncollectible accounts is recorded if the collectability of a receivable balance relating to contractual rent, rental revenue recorded on a straight-line basis, tenant reimbursements or other billed amounts is considered by management to not be probable. At March 31, 2020, and December 31, 2019, the allowance for doubtful accounts totaled $0.9 million and $0.4 million, respectively, on the condensed consolidated balance sheets. Lessee Accounting We determine if an arrangement is a lease at inception. Our operating lease agreements are primarily for real estate space and are included within operating lease right-of-use (“ROU”) assets and operating lease liabilities on the condensed consolidated balance sheets. We elected the practical expedient to combine our lease and related nonlease components for our lessee building leases. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. Our variable lease payments consist of nonlease services related to the lease. Variable lease payments are excluded from the ROU assets and lease liabilities and are recognized in the period in which the obligation for those payments is incurred. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. ROU assets also include any lease payments made and exclude lease incentives. Many of our lessee agreements include options to extend the lease, which we do not include in our minimum lease terms unless they are reasonably certain to be exercised. Rental expense for lease payments related to operating leases is recognized on a straight-line basis over the lease term. Share-Based Compensation We account for share-based compensation using the fair value method of accounting. The estimated fair value of the stock options granted by us is calculated based on the Black-Scholes option-pricing model. The fair value of restricted share-based and Operating Partnership unit compensation is based on the fair value of our common stock on the date of the grant. The fair value of performance share awards, which have a market condition, is based on a Monte Carlo simulation. The fair value for all share-based compensation is amortized on a straight-line basis over the vesting period. We have elected to account for forfeitures as they occur. Asset Retirement and Environmental Remediation Obligations We record accruals for estimated asset retirement and environmental remediation obligations. The obligations relate primarily to the removal of asbestos during development of properties as well as the estimated equipment removal costs upon termination of a certain lease where we are the lessee. At March 31, 2020, and December 31, 2019, the amount included in unearned revenue, prepaid rent and other liabilities on the condensed consolidated balance sheets was approximately $1.7 million at each date. Income Taxes We elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (the “Code”), commencing with our taxable year ended December 31, 2010. To qualify as a REIT, we are required to distribute at least 90% of our taxable income to our stockholders and meet various other requirements imposed by the Code relating to such matters as operating results, asset holdings, distribution levels and diversity of stock ownership. Provided we qualify for taxation as a REIT, we generally are not subject to corporate level federal income tax on the earnings distributed currently to our stockholders. If we fail to qualify as a REIT in any taxable year, and are unable to avail ourselves of certain savings provisions set forth in the Code, all of our taxable income would be subject to federal income tax at regular corporate rates. To maintain REIT status, we must distribute a minimum of 90% of our taxable income. However, it is our policy and intent, subject to change, to distribute 100% of our taxable income and therefore, no provision is required in the accompanying condensed consolidated financial statements for federal income taxes with regard to our activities and our subsidiary pass-through entities. The allocable share of taxable income is included in the income tax returns of its stockholders. We are subject to the statutory requirements of the locations in which we conduct business. State and local income taxes are accrued as deemed required in the best judgment of management based on analysis and interpretation of respective tax laws. We have elected to treat certain subsidiaries as taxable REIT subsidiaries (“TRS”). Certain activities that we undertake must be conducted by a TRS, such as services for our tenants that could be considered otherwise impermissible for us to perform and holding assets that we cannot hold directly. A TRS is subject to corporate level federal and state income taxes. Deferred income taxes are recognized in certain taxable entities. Deferred income tax generally is a function of the period’s temporary differences (items that are treated differently for tax purposes than for financial reporting purposes), the utilization of tax net operating losses generated in prior years that previously had been recognized as deferred income tax assets and the reversal of any previously recorded deferred income tax liabilities. A valuation allowance for deferred income tax assets is provided if we believe all or some portion of the deferred income tax asset may more likely than not be realized. Any increase or decrease in the valuation allowance resulting from a change in circumstances that causes a change in the estimated realizability of the related deferred income tax asset is included in deferred tax expense. As of March 31, 2020, and December 31, 2019, the gross deferred income taxes were not material. We currently have no liabilities for uncertain income tax positions. The earliest tax year for which we are subject to examination is 2016. Concentration of Credit Risks Our cash and cash equivalents are maintained in various financial institutions, which, at times, may exceed federally insured limits. We have not experienced any losses in such accounts, and management believes that the Company is not exposed to any significant credit risk in this area. We have no off-balance sheet concentrations of credit risk, such as foreign exchange contracts, option contracts, or foreign currency hedging arrangements. Segment Information We manage our business as one reportable segment consisting of investments in data centers located in the United States. Although we provide services in several markets, these operations have been aggregated into one reportable segment based on the similar economic characteristics amongst all markets, including the nature of the services provided and the type of customers purchasing these services. Risks and Uncertainties The full extent of the operational and financial impact of the novel coronavirus (“COVID-19”) outbreak on our business has yet to be determined. The impact of the outbreak of COVID-19 is dependent on future developments, including, among other factors, the duration and spread of the outbreak, along with related government-mandated business shutdowns, travel advisories and restrictions on movement, the recovery time of general employment levels, disrupted supply chains, potentially material staffing shortages, construction and development delays, and uncertainty with respect to accessibility of additional funding sources. In addition, some of our customers and prospective customers are dependent on areas of the economy that have been significantly impacted by the outbreak of COVID-19, which may impact their ability to comply with their rent obligations or their demand for additional space and power from us. As of March 31, 2020, we have not recognized a material loss, impairment, or contingency within our condensed consolidated financial statements as a result of the COVID-19 pandemic.

Investment in Real Estate

Investment in Real Estate	3 Months Ended
Investment in Real Estate	Mar. 31, 2020
Investment in Real Estate
Investment in Real Estate	3. Investment in Real Estate The following is a summary of the properties owned or leased by market at March 31, 2020 (in thousands): Buildings and Construction in Market Land Improvements Progress Total Cost Boston $ 5,154 $ 119,803 $ 3,005 $ 127,962 Chicago 5,493 115,909 110,768 232,170 Denver — 34,938 386 35,324 Los Angeles 18,672 377,134 81,178 476,984 Miami 728 14,641 — 15,369 New York 2,729 173,080 54,719 230,528 Northern Virginia 21,856 401,645 101,718 525,219 San Francisco Bay 39,961 778,380 86,020 904,361 Total $ 94,593 $ 2,015,530 $ 437,794 $ 2,547,917 The following is a summary of the properties owned or leased by market at December 31, 2019 (in thousands): Market Land Buildings and Construction in Total Cost Boston $ 5,154 $ 119,227 $ 931 $ 125,312 Chicago 5,493 115,699 100,118 221,310 Denver — 32,659 2,461 35,120 Los Angeles 18,672 376,525 60,178 455,375 Miami 728 14,491 133 15,352 New York 2,729 155,746 56,271 214,746 Northern Virginia 21,856 398,742 101,619 522,217 San Francisco Bay 39,961 776,642 72,763 889,366 Total $ 94,593 $ 1,989,731 $ 394,474 $ 2,478,798

Other Assets

Other Assets	3 Months Ended
Other Assets	Mar. 31, 2020
Other Assets.
Other Assets	4. Other Assets Other assets consisted of the following, net of amortization and depreciation, if applicable for each line item, as of March 31, 2020, and December 31, 2019 (in thousands): March 31, December 31, 2020 2019 Deferred rent receivable $ 38,831 $ 38,335 Initial direct costs 28,591 26,371 Internal-use software 16,699 16,747 Prepaid expenses 12,178 7,675 Corporate furniture, fixtures and equipment 4,507 4,848 Deferred financing costs - revolving credit facility 3,076 3,148 Other 673 3,958 Total $ 104,555 $ 101,082

Leases

Leases	3 Months Ended
Leases	Mar. 31, 2020
Leases
Leases	5. Leases As the lessee, we currently lease real estate space under noncancelable operating lease agreements for our turn-key data centers at NY1, LA1, LA4, DC1, DC2, DE1, and DE2, and our corporate headquarters located in Denver, Colorado. Our leases have remaining lease terms ranging from 1 year to 15 years, some of the leases include options to extend the leases for up to an additional 20 years. We do not include any of our renewal options in our lease terms for calculating our lease liability as the renewal options allow us to maintain operational flexibility and we are not reasonably certain we will exercise these renewal options at this time. The weighted-average remaining non-cancelable lease term for our operating leases was nine years at March 31, 2020, and December 31, 2019. The weighted-average discount rate was 4.9% at each date. During the three months ended March 31, 2020, we extended the term of approximately 25,000 NRSF at our existing DC2 data center from July 2028 to July 2035. As a result of this extension, we remeasured the lease liability and adjusted the ROU asset by approximately $7.0 million. The components of lease expense were as follows (in thousands): Three Months Ended March 31, 2020 2019 Lease expense: Operating lease expense $ 6,862 $ 6,396 Variable lease expense 1,537 1,292 Rent expense $ 8,399 $ 7,688

Lease Revenue

Lease Revenue	3 Months Ended
Lease Revenue	Mar. 31, 2020
Lease Revenue
Lease Revenue	6. Lease Revenue The components of data center, office, light-industrial, and other lease revenue were as follows (in thousands): Three Months Ended March 31, 2020 2019 Lease revenue: Minimum lease revenue $ 106,441 $ 99,410 Variable lease revenue 20,836 21,069 Total lease revenue $ 127,277 $ 120,479

Debt

Debt	3 Months Ended
Debt	Mar. 31, 2020
Debt
Debt	7. Debt A summary of outstanding indebtedness as of March 31, 2020, and December 31, 2019, is as follows (in thousands): Maturity March 31, December 31, Interest Rate Date 2020 2019 Revolving credit facility (1) 2.45% and 3.01% at March 31, 2020, and December 31, 2019, respectively November 8, 2023 $ 155,500 $ 62,500 2022 Senior unsecured term loan (1) 1.76% and 2.96% at March 31, 2020, and December 31, 2019, respectively April 19, 2022 200,000 200,000 2023 Senior unsecured notes 4.19% at March 31, 2020, and December 31, 2019, respectively June 15, 2023 150,000 150,000 2024 Senior unsecured term loan (1) 2.86% and 3.44% at March 31, 2020, and December 31, 2019, respectively April 19, 2024 150,000 150,000 2024 Senior unsecured notes 3.91% at March 31, 2020, and December 31, 2019, respectively April 20, 2024 175,000 175,000 2025 Senior unsecured term loan (1) 2.32% and 2.81% at March 31, 2020, and December 31, 2019, respectively April 1, 2025 350,000 350,000 2026 Senior unsecured notes (1) 4.52% at March 31, 2020, and December 31, 2019, respectively April 17, 2026 200,000 200,000 2029 Senior unsecured notes 4.31% at March 31, 2020, and December 31, 2019, respectively April 17, 2029 200,000 200,000 Total principal outstanding ` 1,580,500 1,487,500 Unamortized deferred financing costs (8,493) (9,098) Total debt $ 1,572,007 $ 1,478,402 (1) Our Operating Partnership has in place swap agreements with respect to the term loans noted above. The interest rates presented represent the effective interest rates as of March 31, 2020, and December 31, 2019, including the impact of the interest rate swaps, which effectively fix the interest rate on a portion of our variable rate debt. We entered into three new interest rate swaps during the quarter ended March 31, 2020. See Note 8 – Derivatives and Hedging Activities. Revolving Credit Facility On November 8, 2019, our Operating Partnership and certain subsidiary co-borrowers entered into the Fifth Amended and Restated Credit Agreement (as amended and restated, the “Amended and Restated Credit Agreement”), which amended and restated our previous credit agreement, to provide additional liquidity of $100 million, which was used to pay down a portion of the then-existing revolving credit facility and for general corporate purposes. The Amended and Restated Credit Agreement, among other things, decreased the interest rates on borrowings under the revolving credit facility and certain term loans, and extended the maturity date from April 19, 2022, to November 8, 2023, with a one-time extension option, which, if exercised, would extend the maturity date to November 8, 2024. The exercise of the extension option is subject to payment of an extension fee equal to 10 basis points of total commitments under the Amended and Restated Credit Agreement at initial maturity and certain other customary conditions. The Amended and Restated Credit Agreement increased our total commitment from $850 million to $950 million, consisting of a $450 million revolving credit facility, a $150 million senior unsecured term loan scheduled to mature on April 19, 2024, and a $350 million senior unsecured term loan scheduled to mature on April 1, 2025. See “2024 Senior Unsecured Term Loan” and “2025 Senior Unsecured Term Loan” below for a discussion of the $150 million and $350 million senior unsecured term loans, respectively. The Amended and Restated Credit Agreement also increased our accordion feature by $200 million to $550 million, which allows our Operating Partnership to increase our total commitments from $950 million to $1.5 billion, under specified circumstances, including securing capital from new or existing lenders. Borrowings under the revolving credit facility were amended to bear interest at a variable rate per annum equal to either (i) LIBOR plus 125 basis points to 185 basis points, or (ii) a base rate plus 25 basis points to 85 basis points, each depending on our Operating Partnership’s leverage ratio. At March 31, 2020, our Operating Partnership’s leverage ratio was 31.2% and the interest rate was LIBOR plus 125 basis points. The total amount available for borrowing under the revolving credit facility, is equal to the lesser of $450.0 million or the availability calculated based on our unencumbered asset pool. As of March 31, 2020, the borrowing capacity was $450.0 million. As of March 31, 2020, $155.5 million was borrowed and outstanding, $6.1 million was outstanding under letters of credit, and therefore $288.4 million remained available for us to borrow under the revolving credit facility. Our ability to borrow under the Amended and Restated Credit Agreement is subject to ongoing compliance with a number of financial covenants and other customary restrictive covenants, including, among others: ● a maximum leverage ratio (defined as total consolidated indebtedness to total gross asset value) of 60% , which, as of March 31, 2020, was 31.2% ● a maximum secured debt ratio (defined as total consolidated secured debt to total gross asset value) of 40% , which, as of March 31, 2020, was 0.0% ● a minimum fixed charge coverage ratio (defined as adjusted consolidated earnings before interest, taxes, depreciation and amortization to consolidated fixed charges) of 1.5 to 1.0, which, as of March 31, 2020, was 5.8 to 1.0. The Amended and Restated Credit Agreement ranks pari passu with the 2022 Term Loan, the 2024 Term Loan, the 2025 Term Loan, the 2023 Notes, the 2024 Notes, the 2026 Notes, and the 2029 Notes (each as defined herein) and contains the same financial covenants and other customary restrictive covenants as those debt instruments. In connection with the Amended and Restated Credit Agreement, the revolving credit facility and senior unsecured term loans were amended to remove or change certain financial covenants and other customary restrictive covenants, including removal of covenants limiting distributions (except upon an event of default), incurrence of unhedged variable rate debt, and increases or decreases, as applicable, to a number of ratios and other figures in the Amended and Restated Credit Agreement, resulting in increased flexibility for our Operating Partnership. As of March 31, 2020, we were in compliance with all of the financial covenants under the Amended and Restated Credit Agreement. 2022 Senior Unsecured Term Loan On April 19, 2017, our Operating Partnership and certain subsidiaries entered into an Amended and Restated Term Loan Agreement (as amended and restated, the “Term Loan Agreement”), which amended and restated the $100 million senior unsecured term loan, originally entered into on January 31, 2014 (the “2022 Term Loan”). The Term Loan Agreement was amended and restated to, among other things, (i) exercise the accordion feature to increase the total commitments to $200 million, (ii) extend the maturity of the term loan from January 31, 2019, to April 19, 2022, (iii) amend the accordion feature to allow an increase in total commitments from $200 million to $300 million, under specified circumstances, including securing capital from new or existing lenders, and (iv) explicitly permit the issuance of the 2024 Notes. The 2022 Term Loan ranks pari passu with the 2024 Term Loan, the 2025 Term Loan, the 2023 Notes, the 2024 Notes, the 2026 Notes, the 2029 Notes and the Amended and Restated Credit Agreement and contains the same financial covenants and other customary restrictive covenants as those debt instruments. As of March 31, 2020, we were in compliance with all of the financial covenants under the 2022 Term Loan. Borrowings under the 2022 Term Loan bear interest at a variable rate per annum equal to either (i) LIBOR plus 120 basis points to 180 basis points, or (ii) a base rate plus 20 basis points to 80 basis points, each depending on our Operating Partnership’s leverage ratio. At March 31, 2020, our Operating Partnership’s leverage ratio was 31.2% and the interest rate was LIBOR plus 120 basis points. 2024 Senior Unsecured Term Loan On November 8, 2019, pursuant to the terms of the Amended and Restated Credit Agreement, our Operating Partnership and certain subsidiaries extended the term of the $150 million senior unsecured term loan (as amended, the “2024 Term Loan”) from April 19, 2023, to April 19, 2024. The 2024 Term Loan ranks pari passu with the 2022 Term Loan, the 2025 Term Loan, the 2023 Notes, the 2024 Notes, the 2026 Notes, the 2029 Notes, and the Amended and Restated Credit Agreement and contains the same financial covenants and other customary restrictive covenants as those debt instruments. As of March 31, 2020, we were in compliance with all of the financial covenants under the 2024 Term Loan. Borrowings under the 2024 Term Loan bear interest at a variable rate per annum equal to either (i) LIBOR plus 120 basis points to 180 basis points, or (ii) a base rate plus 20 basis points to 80 basis points, each depending on our Operating Partnership’s leverage ratio. At March 31, 2020, our Operating Partnership’s leverage ratio was 31.2% and the interest rate was LIBOR plus 120 basis points. 2025 Senior Unsecured Term Loan On November 8, 2019, pursuant to the terms of the Amended and Restated Credit Agreement, our Operating Partnership and certain subsidiaries entered into a new $350 million senior unsecured term loan (the “2025 Term Loan”) maturing on April 1, 2025. The proceeds from the 2025 Term Loan were used to pay down the previous $150 million 2020 Term Loan and the $100 million 2021 Term Loan, pay down a portion of the then-existing revolving credit facility, and for general corporate purposes. The 2025 Term Loan ranks pari passu with the 2022 Term Loan, the 2024 Term Loan, the 2023 Notes, the 2024 Notes, the 2026 Notes, the 2029 Notes, and the Amended and Restated Credit Agreement and contains the same financial covenants and other customary restrictive covenants as those debt instruments. As of March 31, 2020, we were in compliance with all of the financial covenants under the 2025 Term Loan. Borrowings under the 2025 Term Loan bear interest at a variable rate per annum equal to either (i) LIBOR plus 120 basis points to 180 basis points, or (ii) a base rate plus 20 basis points to 80 basis points, each depending on our Operating Partnership’s leverage ratio. At March 31, 2020, our Operating Partnership’s leverage ratio was 31.2% and the interest rate was LIBOR plus 120 basis points. 2023 Senior Unsecured Notes On June 15, 2016, our Operating Partnership issued an aggregate principal amount of $150 million, 4.19% senior unsecured notes due June 15, 2023 (the “2023 Notes”), in a private placement to certain accredited investors. The terms of the 2023 Notes are governed by a note purchase agreement, dated June 15, 2016 (the “2023 Note Purchase Agreement”), by and among our Operating Partnership, the Company and the purchasers of the 2023 Notes. Interest is payable semiannually, on the 15 th Our Operating Partnership may prepay all or a portion of the 2023 Notes upon notice to the holders for 100% of the principal amount so prepaid plus a make-whole premium as set forth in the 2023 Note Purchase Agreement. Upon the occurrence of certain change of control events, holders of the 2023 Notes have the right to require our Operating Partnership to purchase 100% of such holder’s 2023 Notes in cash at a purchase price equal to 100% of the principal amount thereof plus accrued and unpaid interest, if any, to the date of repurchase. The 2023 Notes rank pari passu with the 2022 Term Loan, the 2024 Term Loan, the 2025 Term Loan, the 2024 Notes, the 2026 Notes, the 2029 Notes and the Amended and Restated Credit Agreement. On June 12, 2018, the 2023 Note Purchase Agreement was amended to, among other things, conform to the same financial covenants as the Amended and Restated Credit Agreement, as described above. In addition, certain additional financial covenants in the Amended and Restated Credit Agreement were automatically incorporated into the 2023 Note Purchase Agreement, and, subject to certain conditions, these additional financial covenants will be deleted, removed, amended or otherwise modified to be more or less restrictive if the analogous covenant in the Credit Agreement is so deleted, removed, amended or otherwise modified. These covenants are subject to a number of exceptions and qualifications set forth in the 2023 Note Purchase Agreement. As of March 31, 2020, we were in compliance with all of the financial covenants under the 2023 Note Purchase Agreement. 2024 Senior Unsecured Notes On April 20, 2017, our Operating Partnership issued an aggregate principal amount of $175 million, 3.91% senior unsecured notes due April 20, 2024 (the “2024 Notes”), in a private placement to certain accredited investors. The terms of the 2024 Notes are governed by a note purchase agreement, dated April 20, 2017 (the “2024 Note Purchase Agreement”), by and among our Operating Partnership, the Company and the purchasers of the 2024 Notes. Interest is payable semiannually, on the 15 th Our Operating Partnership may prepay all or a portion of the 2024 Notes upon notice to the holders for 100% of the principal amount plus a make-whole premium as set forth in the 2024 Note Purchase Agreement. Upon the occurrence of certain change of control events, holders of the 2024 Notes would have the right to require our Operating Partnership to purchase 100% of such holders’ 2024 Notes in cash at a purchase price equal to 100% of the principal amount thereof plus accrued and unpaid interest, if any, to the date of repurchase. The 2024 Notes rank pari passu with the 2022 Term Loan, the 2024 Term Loan, the 2025 Term Loan, the 2023 Notes, the 2026 Notes, the 2029 Notes and the Amended and Restated Credit Agreement. On June 12, 2018, the 2024 Note Purchase Agreement was amended to, among other things, conform to the same financial covenants as the Amended and Restated Credit Agreement, as described above. In addition, certain additional financial covenants in the Amended and Restated Credit Agreement were automatically incorporated into the 2024 Note Purchase Agreement, and, subject to certain conditions, these additional financial covenants will be deleted, removed, amended or otherwise modified to be more or less restrictive if the analogous covenant in the Amended and Restated Credit Agreement is so deleted, removed, amended or otherwise modified. These covenants are subject to a number of exceptions and qualifications set forth in the 2024 Note Purchase Agreement. As of March 31, 2020, we were in compliance with all of the financial covenants under the 2024 Note Purchase Agreement. 2026 Senior Unsecured Notes On April 17, 2019, our Operating Partnership issued an aggregate principal amount of $200 million, 4.11% Series A senior unsecured notes due April 17, 2026 (the “2026 Notes”), in a private placement to certain accredited investors. After giving effect to cancellation costs incurred in connection with the termination of an interest rate swap agreement entered into in anticipation of the issuance of the Notes, the 2026 Notes bear an effective interest rate of 4.52% per annum. The terms of the 2026 Notes are governed by a note purchase agreement, dated April 17, 2019 (the “2026 Note Purchase Agreement”), by and among our Operating Partnership, the Company and the purchasers of the 2026 Notes. Interest is payable semiannually, on the 15 th Our Operating Partnership may prepay all or a portion of the 2026 Notes upon notice to the holders for 100% of the principal amount so prepaid plus a make-whole premium as set forth in the 2026 Note Purchase Agreement. Upon the occurrence of certain change of control events, holders of the 2026 Notes would have the right to require our Operating Partnership to purchase 100% of such holders’ 2026 Notes in cash at a purchase price equal to 100% of the principal amount thereof plus accrued and unpaid interest, if any, to the date of repurchase. The 2026 Notes rank pari passu with the 2022 Term Loan, the 2024 Term Loan, the 2025 Term Loan, the 2023 Notes, the 2024 Notes, the 2029 Notes and the Amended and Restated Credit Agreement. The 2026 Note Purchase Agreement conforms to the same financial covenants as the Amended and Restated Credit Agreement, as described above. In addition, on the date of the 2026 Note Purchase Agreement and from time to time, certain additional financial covenants in the Amended and Restated Credit Agreement will be automatically incorporated into the 2026 Note Purchase Agreement and, subject to certain conditions, will be deleted, removed, amended or otherwise modified to be more or less restrictive if the analogous covenant in the Amended and Restated Credit Agreement is so deleted, removed, amended or otherwise modified. These covenants are subject to a number of exceptions and qualifications set forth in the 2026 Note Purchase Agreement. As of March 31, 2020, we were in compliance with all of the financial covenants under the 2026 Note Purchase Agreement. 2029 Senior Unsecured Notes As mentioned above, on April 17, 2019, our Operating Partnership entered into the 2026 Note Purchase Agreement to issue the 2026 Notes and an additional aggregate principal amount of $200 million, 4.31% Series B senior unsecured notes due April 17, 2029 (the “2029 Notes”), in a private placement to certain accredited investors. An aggregate principal amount of $125 million of the 2029 Notes was issued on April 17, 2019. The remaining $75 million of the 2029 Notes was issued on July 17, 2019. The terms of the 2029 Notes are governed by the 2026 Note Purchase Agreement, by and among our Operating Partnership, the Company and the purchasers of the 2029 Notes. Interest is payable semiannually, on the 15 th Our Operating Partnership may prepay all or a portion of the 2029 Notes upon notice to the holders for 100% of the principal amount plus a make-whole premium as set forth in the 2026 Note Purchase Agreement. Upon the occurrence of certain change of control events, holders of the 2029 Notes would have the right to require our Operating Partnership to purchase 100% of such holders’ 2029 Notes in cash at a purchase price equal to 100% of the principal amount thereof plus accrued and unpaid interest, if any, to the date of repurchase. The 2029 Notes rank pari passu with the 2022 Term Loan, the 2024 Term Loan, the 2025 Term Loan, the 2023 Notes, the 2024 Notes, the 2026 Notes and the Amended and Restated Credit Agreement. As of March 31, 2020, we were in compliance with all of the financial covenants under the 2026 Note Purchase Agreement. Debt Maturities The following table summarizes when our debt currently becomes due (in thousands): Year Ending December 31, 2020 $ — 2021 — 2022 200,000 2023 305,500 2024 325,000 Thereafter 750,000 Total principal outstanding 1,580,500 Unamortized deferred financing costs (8,493) Total debt, net $ 1,572,007 Subsequent Debt Financing On April 15, 2020, we agreed with lenders on the pricing of 7-year

Derivatives and Hedging Activit

Derivatives and Hedging Activities	3 Months Ended
Derivatives and Hedging Activities	Mar. 31, 2020
Derivatives and Hedging Activities
Derivatives and Hedging Activities	8. Derivatives and Hedging Activities The following table summarizes our derivative positions as of March 31, 2020, and December 31, 2019 (in thousands): Notional Amount Fair Value (Level 2) (1) March 31, December 31, Type of Effective Expiration March 31, December 31, 2020 2019 Derivative Index Strike Rate Date Date 2020 2019 $ 75,000 $ 75,000 Interest Rate Swap 1 mo. LIBOR 1.43 % 5/5/2015 5/5/2020 $ (30) $ 67 75,000 75,000 Interest Rate Swap 1 mo. LIBOR 2.72 5/5/2018 4/5/2023 (5,469) (2,819) 100,000 100,000 Interest Rate Swap 1 mo. LIBOR 1.59 11/8/2019 4/1/2025 (5,918) 55 75,000 75,000 Interest Rate Swap 1 mo. LIBOR 1.59 11/8/2019 4/1/2025 (4,439) 41 200,000 — Interest Rate Swap 1 mo. LIBOR 0.56 3/5/2020 4/19/2022 (1,104) — 75,000 — Interest Rate Swap 1 mo. LIBOR 0.61 3/5/2020 10/5/2023 (738) — 175,000 — Interest Rate Swap 1 mo. LIBOR 0.64 3/5/2020 10/1/2024 (2,075) — $ 775,000 $ 325,000 $ (19,773) $ (2,656) (1) Derivative assets are recorded at fair value in our condensed consolidated balance sheets in other assets and derivative liabilities are recorded at fair value in our condensed consolidated balance sheets in unearned revenue, prepaid rent and other liabilities. We do not net our derivative position by counterparty for purposes of balance sheet presentation and disclosure. Risk Management Objective of Using Derivatives We are exposed to certain risks arising from both our business operations and economic conditions. We principally manage our exposures to a wide variety of business and operational risks through management of our core business activities. We manage economic risks, including interest rate, liquidity, and credit risk primarily by managing the amount, sources, and duration of our debt funding and the use of derivative financial instruments. Specifically, we enter into derivative financial instruments to manage exposures that arise from business activities that result in the receipt or payment of future known or uncertain cash amounts, the value of which are determined by interest rates. Our derivative financial instruments are used to manage differences in the amount, timing, and duration of our known or expected cash receipts and our known or expected cash payments principally related to our investments and borrowings. Cash Flow Hedges of Interest Rate Risk Our objectives in using interest rate derivatives are to reduce variability in interest expense and to manage our exposure to adverse interest rate movements. To accomplish this objective, we primarily use interest rate swaps as part of our 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. The changes in the fair value of derivatives designated and that qualify as effective cash flow hedges is recorded in accumulated other comprehensive income or loss on the condensed consolidated balance sheets and is subsequently reclassified into earnings in the period that the hedged forecasted transaction affects earnings. Amounts reported in accumulated other comprehensive income related to derivatives will be reclassified to interest expense as interest payments are made on our variable-rate debt. During the subsequent twelve months, beginning April 1, 2020, we estimate that $6.0 million will be reclassified as an increase to interest expense.

Stockholders' Equity

Stockholders' Equity	3 Months Ended
Stockholders' Equity	Mar. 31, 2020
Stockholders' Equity
Stockholders' Equity	9. Stockholders’ Equity We announced the following dividends per share on our common stock during the three months ended March 31, 2020: Declaration Date Record Date Payment Date Common Stock March 5, 2020 March 31, 2020 April 15, 2020 $ 1.22

Noncontrolling Interests - Oper

Noncontrolling Interests - Operating Partnership	3 Months Ended
Noncontrolling Interests - Operating Partnership	Mar. 31, 2020
Noncontrolling Interests - Operating Partnership
Noncontrolling Interests - Operating Partnership	10. Noncontrolling Interests — Operating Partnership Noncontrolling interests represent the limited partnership interests in our Operating Partnership held by individuals and entities other than CoreSite Realty Corporation. The current holders of common Operating Partnership units are eligible to have the common Operating Partnership units redeemed for cash or common stock on a one-for-one basis, at our option. The following table shows the common ownership interests in our Operating Partnership as of March 31, 2020, and December 31, 2019: March 31, 2020 December 31, 2019 Number of Units Percentage of Total Number of Units Percentage of Total CoreSite Realty Corporation 37,394,352 77.6 % 37,244,987 77.6 % Noncontrolling interests 10,769,518 22.4 10,771,658 22.4 Total 48,163,870 100.0 % 48,016,645 100.0 % For each share of common stock issued by us, our Operating Partnership issues to us an equivalent common Operating Partnership unit. During the three months ended March 31, 2020, we issued 149,365 shares of common stock related to employee compensation arrangements and therefore an equivalent number of common Operating Partnership units were issued to us by our Operating Partnership. Holders of common Operating Partnership units received aggregate distributions of $1.22 per unit during the three months ended March 31, 2020, payable in correlation with declared dividends on shares of our common stock. The redemption value of the noncontrolling interests at March 31, 2020, was $1.2 billion based on the closing price of the Company’s common stock of $115.90 per share on the last trading day prior to that date.

Equity Incentive Plan

Equity Incentive Plan	3 Months Ended
Equity Incentive Plan	Mar. 31, 2020
Equity Incentive Award Plan
Equity Incentive Plan	11. Equity Incentive Plan Our Board of Directors adopted and, with the approval of our stockholders, amended the 2010 Equity Incentive Plan (as amended, the “2010 Plan”) in 2013. The 2010 Plan is administered by the Compensation Committee of our Board of Directors. Awards issuable under the 2010 Plan include common stock, stock options, restricted stock, restricted stock units, stock appreciation rights, dividend equivalents, Operating Partnership units and other incentive awards. We have reserved a total of 6,000,000 shares of our common stock for issuance pursuant to the 2010 Plan, which may be adjusted for changes in our capitalization and certain corporate transactions. To the extent that an award expires, terminates or lapses, or an award is settled in cash without the delivery of shares of common stock to the participant, then any unvested shares subject to the award will be available for future grant or sale under the 2010 Plan. Shares of restricted stock that are forfeited or repurchased by us pursuant to the 2010 Plan may again be awarded under the 2010 Plan. The payment of dividend equivalents in cash in conjunction with any outstanding awards will not be counted against the shares available for issuance under the 2010 Plan. As of March 31, 2020, 2,474,370 shares of our common stock were available for issuance pursuant to the 2010 Plan. Stock Options Stock option awards are granted with an exercise price equal to the closing market price of the Company’s common stock on the date of grant. The fair value of each option granted under the 2010 Plan is estimated on the date of grant using the Black-Scholes option-pricing model. The fair values are amortized on a straight-line basis over the vesting periods. Stock options have not been granted since the year ended December 31, 2013. As of March 31, 2020, all stock option awards are fully vested. The following table sets forth stock option activity under the 2010 Plan for the three months ended March 31, 2020: Number of Shares Weighted- Subject to Average Option Exercise Price Options outstanding, December 31, 2019 31,746 $ 19.57 Granted — — Exercised (3,210) 18.87 Forfeited — — Expired — — Options outstanding, March 31, 2020 28,536 $ 19.65 Restricted Stock Awards and Units Restricted stock awards and restricted stock units (“RSUs”) are granted with a fair value equal to the closing market price of the Company’s common stock on the date of grant. The principal difference between restricted stock awards and RSUs is that RSUs are not shares of our common stock and do not have any of the rights or privileges thereof, including voting rights. On the applicable vesting date, the holder of an RSU becomes entitled to a share of common stock. The restricted stock awards and RSUs are amortized on a straight-line basis to expense over the vesting period. The following table sets forth the number of unvested restricted stock awards and RSUs and the weighted-average fair value of these awards at the date of grant: Restricted Weighted- Stock Average Fair Awards and Value at Grant Units Date Unvested balance, December 31, 2019 292,373 $ 96.44 Granted 146,582 110.73 Forfeited (4,913) 99.04 Vested (112,245) 90.76 Unvested balance, March 31, 2020 321,797 $ 104.90 As of March 31, 2020, total unearned compensation on restricted stock awards and RSUs was approximately $32.0 million, and the weighted-average vesting period was 2. Performance Stock Awards We grant long-term incentives to members of management in the form of performance-based restricted stock awards (“PSAs”) under the 2010 Plan. The number of PSAs earned is based on our achievement of relative total shareholder return (“TSR”) measured versus the MSCI US REIT Index over a three-year performance period and ranges between 25% and 175% of the target number of shares for PSAs granted in 2018, 2019, and 2020. The PSAs are granted at the maximum percentage of target and are retired annually to the extent we do not meet the maximum relative TSR performance threshold versus the MSCI US REIT Index. The PSAs are earned upon TSR achievement measured both annually The following table sets forth the number of unvested PSAs and the weighted-average fair value of these awards at the date of grant: Weighted- Average Fair Performance-Based Restricted Stock Awards Value at Grant Minimum Maximum Target Date Unvested balance, December 31, 2019 34,624 171,351 102,989 $ 107.84 Granted 10,210 71,488 40,852 125.02 Performance adjustment (1) 38,047 (7,904) 15,073 — Forfeited (1,049) (4,878) (2,964) 107.63 Vested (32,524) (32,524) (32,524) 105.55 Unvested balance, March 31, 2020 49,308 197,533 123,426 $ 113.96 (1) Includes the annual adjustment for the number of PSAs earned based on our achievement of relative TSR measured versus the MSCI US REIT Index for the applicable performance periods. As of March 31, 2020, total unearned compensation on PSAs was approximately $9.6 million, and the weighted-average vesting period was 2.4 years. The fair value of each PSA award is estimated on the date of grant using a Monte Carlo simulation. The simulation requires assumptions for expected volatility, risk-free rate of return, and dividend yield. The following table summarizes the assumptions used to value the PSAs granted during the three months ended March 31, 2020, and 2019 Three Months Ended March 31, 2020 2019 Expected term (in years) 2.82 2.82 Expected volatility 24.00 % 24.09 % Expected annual dividend (1) — — Risk-free rate 0.56 % 2.48 % (1) The fair value of the PSAs assumes reinvestment of dividends.

Earnings Per Share

Earnings Per Share	3 Months Ended
Earnings Per Share	Mar. 31, 2020
Earnings Per Share
Earnings Per Share	12. Earnings Per Share Basic net income per share is calculated by dividing the net income attributable to common shares by the weighted-average number of common shares outstanding during the period. Diluted net income per share adjusts basic net income per share for the effects of potentially dilutive common shares, if the effect is not antidilutive. Potentially dilutive common stock consists of shares issuable under the 2010 Plan. The following is a summary of basic and diluted net income per share (in thousands, except share and per share amounts): Three Months Ended March 31, 2020 2019 Net income attributable to common shares $ 17,848 $ 19,661 Weighted-average common shares outstanding - basic 37,335,892 36,347,781 Effect of potentially dilutive common shares: Stock options 25,298 38,921 Unvested awards 143,159 160,363 Weighted-average common shares outstanding - diluted 37,504,349 36,547,065 Net income per share attributable to common shares Basic $ 0.48 $ 0.54 Diluted $ 0.48 $ 0.54 In the calculations above, we have excluded weighted-average potentially dilutive securities of 2,054 and 39,754 for the three months ended March 31, 2020, and 2019, respectively, as their effect would have been antidilutive.

Estimated Fair Value of Financi

Estimated Fair Value of Financial Instruments	3 Months Ended
Estimated Fair Value of Financial Instruments	Mar. 31, 2020
Estimated Fair Value of Financial Instruments
Estimated Fair Value of Financial Instruments	13. Estimated Fair Value of Financial Instruments Authoritative guidance issued by FASB establishes a hierarchy of valuation techniques based on the observability of inputs utilized in measuring assets and liabilities at fair values. This hierarchy establishes market-based or observable inputs as the preferred source of values, followed by valuation models using management assumptions in the absence of market inputs. The three levels of the hierarchy under the authoritative guidance are as follows: Level 1 Level 2 Level 3 Our financial instruments consist of cash and cash equivalents, accounts and other receivables, interest rate swaps, the revolving credit facility, the senior unsecured term loans, senior unsecured notes, interest payable and accounts payable. The carrying values of cash and cash equivalents, accounts and other receivables, interest payable and accounts payable approximate fair values due to the short-term nature of these financial instruments. The interest rate swaps are recorded at fair value. The valuation of our derivatives is determined using widely accepted valuation techniques including discounted cash flow analysis on the expected cash flows of each derivative, which reflects the contractual terms of the derivatives, including the period to maturity, and uses observable market-based inputs, including interest rate curves. We have determined that the majority of the inputs used to value our derivatives fall within Level 2 of the fair value hierarchy; however, the credit valuation adjustments associated with our derivatives utilize Level 3 inputs, such as estimates of current credit spreads, to evaluate the likelihood of default by our Operating Partnership and its counterparties. As of March 31, 2020, we have assessed the significance of the impact of the credit valuation adjustments on the overall valuation of our derivative positions and have determined that the credit valuation adjustment is not significant to the overall valuation of our derivative portfolio. As a result, we classify our derivative valuation in Level 2 of the fair value hierarchy. The total principal balance of our revolving credit facility, senior unsecured term loans, and senior unsecured notes was $1.6 billion and $1.5 billion as of March 31, 2020, and December 31, 2019, which approximates the fair value based on Level 3 inputs from the fair value hierarchy. Under the discounted cash flow method, the fair values of the revolving credit facility, the senior unsecured term loans, and the senior unsecured notes are based on our assumptions of market interest rates and terms available incorporating our credit risk for similar loan maturities. Our lease liabilities are determined based on the estimated present value of our minimum lease payments under our lease agreements at lease commencement. The discount rate used to determine the lease liabilities is based on our estimated incremental borrowing rate at lease commencement, based on Level 3 inputs from the fair value hierarchy.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2020
Commitments and Contingencies.
Commitments and Contingencies	14. Commitments and Contingencies Our properties require periodic investments of capital for general capital improvements and for tenant-related capital expenditures. We enter into various construction and equipment contracts with third parties for the development of our properties. At March 31, 2020, we had open commitments related to construction contracts of approximately $145.7 million. Additionally, we have commitments related to telecommunications capacity used to connect data centers located within the same market or geographical area, power usage, and company-wide improvements that are ancillary to revenue generation. At March 31, 2020, we had open commitments related to these contracts of approximately $75.2 million, of which $5.7 million is scheduled to be met during the remainder of the year ending December 31, 2020. In the ordinary course of business, we are subject to claims and administrative proceedings. We are not presently party to any proceeding, which we believe to be material or which we would expect to have, individually or in the aggregate, a material adverse effect on our business, financial condition, cash flows or results of operations. The outcome of litigation and administrative proceedings is inherently uncertain. Therefore, if one or more legal or administrative matters are resolved against us in a reporting period for amounts in excess of management’s expectations, our financial condition, cash flows or results of operations for that reporting period could be materially adversely affected.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2020
Summary of Significant Accounting Policies
Principles of Consolidation and Basis of Presentation	Principles of Consolidation and Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared by our management in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information and in compliance with the rules and regulations of the U.S. Securities and Exchange Commission. Accordingly, these unaudited condensed consolidated financial statements do not include all of the information and footnotes required by GAAP for complete financial statements. In the opinion of our management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included. The results of operations for the three months ended March 31, 2020, are not necessarily indicative of the expected results for the year ending December 31, 2020. These unaudited condensed consolidated financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto included in our Annual Report on Form 10-K Our Operating Partnership meets the definition and criteria of a variable interest entity (“VIE”) and we are the primary beneficiary of the VIE. Our sole significant asset is the investment in our Operating Partnership, and consequently, substantially all of our assets and liabilities represent those assets and liabilities of our Operating Partnership. Our debt is an obligation of our Operating Partnership where the creditors also have recourse against the credit of the Company. Intercompany balances and transactions have been eliminated upon consolidation.
Recent Accounting Pronouncements	Recently Adopted Accounting Pronouncements Fair Value Measurement In August 2018, the Financial Accounting Standards Board (“FASB”) issued guidance codified in Accounting Standards Update (“ASU”) 2018-13, Fair Value Measurement Intangibles – Goodwill and Other – Internal-Use Software In August 2018, the FASB issued guidance codified in ASU 2018-15, Intangibles – Goodwill and Other – Internal-Use Software Financial Instruments – Credit Losses In June 2016, the FASB issued guidance codified in ASU 2016-13, Financial Instruments – Credit Losses Codification Improvements to Topic 326, Financial Instruments – Credit Losses Recent Accounting Pronouncements Not Yet Adopted Reference Rate Reform In March 2020, the FASB issued guidance codified in ASU 2020-04, Reference Rate Reform We determined that all other recently issued accounting pronouncements will not have a material impact on our condensed consolidated financial statements or do not apply to our operations.
Use of Estimates	Use of Estimates The preparation of these unaudited condensed consolidated financial statements, in conformity with GAAP, requires our management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingencies at the date of the unaudited condensed consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. We evaluate our estimates, including those related to assessing our standalone selling prices, performance-based equity compensation plans and the carrying values of our real estate properties, goodwill, and accrued liabilities. We base our estimates on historical experience, current market conditions, and various other assumptions that we believe to be reasonable under the circumstances. Actual results may vary from those estimates and those estimates could vary under different assumptions or conditions.
Investments in Real Estate	Investments in Real Estate Real estate investments are carried at cost less accumulated depreciation and amortization. The cost of real estate includes the purchase price of property and leasehold improvements. Expenditures for maintenance and repairs are expensed as incurred. Significant renovations and betterments that extend the economic useful lives of assets are capitalized. During land development and construction periods, we capitalize construction costs, legal fees, financing costs, real estate taxes and insurance, rent expense and internal costs of personnel performing development, if such costs are incremental and identifiable to a specific development project. Capitalization of costs begins upon commencement of development efforts and ceases when the project is ready for its intended use and held available for occupancy. Interest is capitalized during the period of development based upon applying the weighted-average borrowing rate to the actual development costs expended. Capitalized interest costs were $3.5 million and $2.6 million for the three months ended March 31, 2020, and 2019, respectively. Depreciation and amortization are calculated using the straight-line method over the following useful lives of the assets: Buildings 27 to 40 years Building improvements 1 to 10 years Leasehold improvements The shorter of the lease term or useful life of the asset Depreciation expense was $36.9 million and $32.2 million for the three months ended March 31, 2020, and 2019, respectively.
Acquisition of Investment in Real Estate	Acquisition of Investment in Real Estate When accounting for business combinations and asset acquisitions, the fair value of the real estate acquired is allocated to the acquired tangible assets, consisting primarily of land, building and building improvements, and identified intangible assets and liabilities, consisting of the value of above-market and below-market leases, value of in-place leases and the value of customer relationships. The primary difference between business combinations and asset acquisitions is that asset acquisitions require cost accumulation and allocation at a relative fair value. Acquisition costs are capitalized for asset acquisitions and are expensed for business combinations. The fair value of the land and building of an acquired property is determined by valuing the property as if it were vacant, and the “as-if-vacant” fair value is then allocated to land and building based on management's determination of the fair values of these assets. Management determines the as-if-vacant fair value of a property using methods similar to those used by independent appraisers. Factors considered by management in performing these analyses include an estimate of carrying costs during the expected lease-up periods considering current market conditions and costs to execute similar leases. The fair value of intangibles related to in-place leases includes the value of lease intangibles for above-market and below-market leases, lease origination costs, and customer relationships, determined on a lease-by-lease basis. Above-market and below-market leases are valued based on the present value (using an interest rate which reflects the risks associated with the leases acquired) of the difference between (i) the contractual amounts to be paid pursuant to the in-place leases and (ii) management's estimate of market lease rates for the corresponding in-place leases, measured over a period equal to the remaining noncancelable term of the lease and, for below-market leases, over a time period equal to the initial term plus any below-market fixed rate renewal periods. Lease origination costs include estimates of costs avoided associated with leasing the property, including tenant allowances and improvements and leasing commissions. Customer relationship intangibles relate to the additional revenue opportunities expected to be generated through rental services, interconnection services, and utility services to be provided to the in-place lease tenants. The capitalized values for above and below-market lease intangibles, lease origination costs, and customer relationships are amortized over the term of the underlying leases or the expected customer relationship. Amortization related to above-market and below-market leases where the Company is the lessor is recorded as either a reduction of or an increase to rental revenue, amortization related to above-market and below-market leases where the Company is the lessee is recorded as either a reduction of or an increase to rent expense. If a lease is terminated prior to its stated expiration, all unamortized amounts relating to that lease are written off. The carrying value of intangible assets is reviewed for impairment in connection with its respective asset group whenever events or changes in circumstances indicate that the asset group may not be recoverable. An impairment loss is recognized if the carrying amount of the asset group is not recoverable and its carrying amount exceeds its estimated fair value. No impairment loss related to these intangible assets was recognized for the three months ended March 31, 2020, or 2019. The excess of the cost of an acquired business over the net of the amounts assigned to assets acquired (including identified intangible assets) and liabilities assumed is recorded as goodwill. As of March 31, 2020, and December 31, 2019, we had $40.6 million of goodwill at each date. The Company’s goodwill has an indeterminate life and is not amortized, but is tested for impairment on an annual basis, or more frequently if events or changes in circumstances indicate that the asset might be impaired. No impairment loss was recognized for the three months ended March 31, 2020, or 2019.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents include all non-restricted cash held in financial institutions and other non-restricted highly liquid short-term investments with original maturities at acquisition of three months or less.
Initial Direct Costs	Initial Direct Costs Initial direct costs include commissions paid to third parties, including brokers, leasing and referral agents, and internal sales commissions paid to employees for successful execution of lease agreements. Initial direct costs are incremental costs that would not have been incurred if the lease agreement had not been executed. These initial direct costs are capitalized and generally amortized over the term of the related leases using the straight-line method. If a customer lease terminates prior to the expiration of its initial term, any unamortized initial direct costs related to the lease are written off to amortization expense. Amortization of initial direct costs was $3.3 million and $3.4 million for the three months ended March 31, 2020, and 2019, respectively. Initial direct costs are included within other assets in the condensed consolidated balance sheets and consisted of the following, net of amortization, as of March 31, 2020, and December 31, 2019 (in thousands): March 31, December 31, 2020 2019 Internal sales commissions $ 15,335 $ 15,064 Third party commissions 12,820 10,845 Other 436 462 Total $ 28,591 $ 26,371
Deferred Financing Costs	Deferred Financing Costs Deferred financing costs include costs incurred in connection with obtaining debt and extending existing debt. These financing costs are capitalized and amortized on a straight-line basis, which approximates the effective-interest method, over the term of the indebtedness and the amortization is included as a component of interest expense. Depending on the type of debt instrument, deferred financing costs are reported either in other assets or as a direct deduction from the carrying amount of the related debt liabilities in our condensed consolidated balance sheets.
Recoverability of Long-Lived Assets	Recoverability of Long-Lived Assets We review our long-lived assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Impairment is recognized when estimated expected future cash flows (undiscounted and without interest charges) are less than the carrying amount of the assets. The estimation of expected future net cash flows is inherently uncertain and relies, to a considerable extent, on assumptions regarding current and future economics and market conditions and the availability of capital. If, in future periods, there are changes in the estimates or assumptions incorporated into the impairment review analysis, the changes could result in an adjustment to the carrying amount of the long-lived assets. To the extent that impairment has occurred, the excess of the carrying amount of long-lived assets over its estimated fair value would be recognized as an impairment loss charged to net income. For the three months ended March 31, 2020, and 2019, no impairment of long-lived assets was recognized in the condensed consolidated financial statements.
Derivative Instruments and Hedging Activities	Derivative Instruments and Hedging Activities We reflect all derivative instruments at fair value as either assets or liabilities on the condensed consolidated balance sheets. For those derivative instruments that are designated and qualify as hedging instruments, we record the gain or loss on the hedging instruments as a component of accumulated other comprehensive income or loss. For derivatives that do not meet the criteria for hedge accounting, changes in fair value are immediately recognized within net income. See additional discussion in Note 8, Derivatives and Hedging Activities.
Internal-Use Software	Internal-Use Software We recognize internal-use software development costs based on the development stage of the project and nature of the cost. Internal and external costs incurred during the preliminary project stage are expensed as they are incurred. Internal and external costs incurred to develop internal-use software during the application development stage are capitalized. Internal and external training costs and maintenance costs during the post-implementation-operation stage are expensed as incurred. Completed projects are placed into service and amortized over the estimated useful life of the software. No impairment of internal-use software was recognized in the condensed consolidated financial statements for the three months ended March 31, 2020, and 2019.
Revenue Recognition	Revenue Recognition Rental, Power, and Related Revenue We derive our revenues from leases with customers for data center and office and light-industrial space. Our leases include rental revenue lease components and nonlease revenue components, such as power and tenant reimbursements. We have elected to combine all of our nonlease revenue components that have the same pattern of transfer as the related operating lease component into a single combined lease component. Our leases with customers are classified as operating leases and rental revenue is recognized on a straight-line basis over the customer lease term. Occasionally, our customer leases include options to extend or terminate the lease agreements. We do not include any of these extension or termination options in a customer’s lease term for lease classification purposes or for recognizing rental revenue unless we are reasonably certain the customer will exercise these extension or termination options. The excess of rents recognized over amounts contractually due pursuant to the underlying leases is recorded as deferred rent receivable within other assets on our condensed consolidated balance sheets. In general, we provide two power products for our data center leased space, consisting of a fixed (breakered-amperage) and a variable (sub-metered) model. Customer power arrangements are coterminous with the customer’s underlying lease and have the same pattern of transfer over the lease term and are therefore combined with lease revenue within our condensed consolidated statements of operations. For fixed power arrangements, a customer pays us a fixed monthly fee for a committed available amount of power. We recognize the fixed power revenue each month over the term of the lease. For variable power arrangements, a customer pays us variable monthly fees for the specific amount of power utilized at the current utility rates. We recognize variable power revenue each month as the uncertainty related to the consideration is resolved, as power is provided to our customers, and as our customers utilize the power. Some of our leases contain provisions under which our customers reimburse us for common area maintenance and other executory costs. These customer reimbursements are variable and are recognized in the period that the expenses are recognized. These services have the same pattern of transfer over the lease term and are also combined with lease revenue within our condensed consolidated statements of operations. Interconnection Revenue We also derive revenue from interconnection services, which are generally contracted on a month-to-month basis cancellable by us or the customer at any time. Interconnection services are accounted for as separate contracts and are not combined with lease and power arrangements. We recognize interconnection revenue each month as these services are delivered to, and utilized by, our customers. Allowance for Doubtful Accounts A provision for uncollectible accounts is recorded if the collectability of a receivable balance relating to contractual rent, rental revenue recorded on a straight-line basis, tenant reimbursements or other billed amounts is considered by management to not be probable. At March 31, 2020, and December 31, 2019, the allowance for doubtful accounts totaled $0.9 million and $0.4 million, respectively, on the condensed consolidated balance sheets.
Lessee Accounting	Lessee Accounting We determine if an arrangement is a lease at inception. Our operating lease agreements are primarily for real estate space and are included within operating lease right-of-use (“ROU”) assets and operating lease liabilities on the condensed consolidated balance sheets. We elected the practical expedient to combine our lease and related nonlease components for our lessee building leases. ROU assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. Our variable lease payments consist of nonlease services related to the lease. Variable lease payments are excluded from the ROU assets and lease liabilities and are recognized in the period in which the obligation for those payments is incurred. As most of our leases do not provide an implicit rate, we use our incremental borrowing rate based on the information available at commencement date in determining the present value of lease payments. ROU assets also include any lease payments made and exclude lease incentives. Many of our lessee agreements include options to extend the lease, which we do not include in our minimum lease terms unless they are reasonably certain to be exercised. Rental expense for lease payments related to operating leases is recognized on a straight-line basis over the lease term.
Share-Based Compensation	Share-Based Compensation We account for share-based compensation using the fair value method of accounting. The estimated fair value of the stock options granted by us is calculated based on the Black-Scholes option-pricing model. The fair value of restricted share-based and Operating Partnership unit compensation is based on the fair value of our common stock on the date of the grant. The fair value of performance share awards, which have a market condition, is based on a Monte Carlo simulation. The fair value for all share-based compensation is amortized on a straight-line basis over the vesting period. We have elected to account for forfeitures as they occur.
Asset Retirement and Environmental Remediation Obligations	Asset Retirement and Environmental Remediation Obligations We record accruals for estimated asset retirement and environmental remediation obligations. The obligations relate primarily to the removal of asbestos during development of properties as well as the estimated equipment removal costs upon termination of a certain lease where we are the lessee. At March 31, 2020, and December 31, 2019, the amount included in unearned revenue, prepaid rent and other liabilities on the condensed consolidated balance sheets was approximately $1.7 million at each date.
Income Taxes	Income Taxes We elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (the “Code”), commencing with our taxable year ended December 31, 2010. To qualify as a REIT, we are required to distribute at least 90% of our taxable income to our stockholders and meet various other requirements imposed by the Code relating to such matters as operating results, asset holdings, distribution levels and diversity of stock ownership. Provided we qualify for taxation as a REIT, we generally are not subject to corporate level federal income tax on the earnings distributed currently to our stockholders. If we fail to qualify as a REIT in any taxable year, and are unable to avail ourselves of certain savings provisions set forth in the Code, all of our taxable income would be subject to federal income tax at regular corporate rates. To maintain REIT status, we must distribute a minimum of 90% of our taxable income. However, it is our policy and intent, subject to change, to distribute 100% of our taxable income and therefore, no provision is required in the accompanying condensed consolidated financial statements for federal income taxes with regard to our activities and our subsidiary pass-through entities. The allocable share of taxable income is included in the income tax returns of its stockholders. We are subject to the statutory requirements of the locations in which we conduct business. State and local income taxes are accrued as deemed required in the best judgment of management based on analysis and interpretation of respective tax laws. We have elected to treat certain subsidiaries as taxable REIT subsidiaries (“TRS”). Certain activities that we undertake must be conducted by a TRS, such as services for our tenants that could be considered otherwise impermissible for us to perform and holding assets that we cannot hold directly. A TRS is subject to corporate level federal and state income taxes. Deferred income taxes are recognized in certain taxable entities. Deferred income tax generally is a function of the period’s temporary differences (items that are treated differently for tax purposes than for financial reporting purposes), the utilization of tax net operating losses generated in prior years that previously had been recognized as deferred income tax assets and the reversal of any previously recorded deferred income tax liabilities. A valuation allowance for deferred income tax assets is provided if we believe all or some portion of the deferred income tax asset may more likely than not be realized. Any increase or decrease in the valuation allowance resulting from a change in circumstances that causes a change in the estimated realizability of the related deferred income tax asset is included in deferred tax expense. As of March 31, 2020, and December 31, 2019, the gross deferred income taxes were not material. We currently have no liabilities for uncertain income tax positions. The earliest tax year for which we are subject to examination is 2016.
Concentration of Credit Risks	Concentration of Credit Risks Our cash and cash equivalents are maintained in various financial institutions, which, at times, may exceed federally insured limits. We have not experienced any losses in such accounts, and management believes that the Company is not exposed to any significant credit risk in this area. We have no off-balance sheet concentrations of credit risk, such as foreign exchange contracts, option contracts, or foreign currency hedging arrangements.
Segment Information	Segment Information We manage our business as one reportable segment consisting of investments in data centers located in the United States. Although we provide services in several markets, these operations have been aggregated into one reportable segment based on the similar economic characteristics amongst all markets, including the nature of the services provided and the type of customers purchasing these services.
Risks and Uncertainties	Risks and Uncertainties The full extent of the operational and financial impact of the novel coronavirus (“COVID-19”) outbreak on our business has yet to be determined. The impact of the outbreak of COVID-19 is dependent on future developments, including, among other factors, the duration and spread of the outbreak, along with related government-mandated business shutdowns, travel advisories and restrictions on movement, the recovery time of general employment levels, disrupted supply chains, potentially material staffing shortages, construction and development delays, and uncertainty with respect to accessibility of additional funding sources. In addition, some of our customers and prospective customers are dependent on areas of the economy that have been significantly impacted by the outbreak of COVID-19, which may impact their ability to comply with their rent obligations or their demand for additional space and power from us. As of March 31, 2020, we have not recognized a material loss, impairment, or contingency within our condensed consolidated financial statements as a result of the COVID-19 pandemic.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
Summary of Significant Accounting Policies (Tables)	Mar. 31, 2020
Summary of Significant Accounting Policies
Schedule of useful lives of real estate investment assets	Buildings 27 to 40 years Building improvements 1 to 10 years Leasehold improvements The shorter of the lease term or useful life of the asset
Schedule of deferred leasing costs, net of amortization	March 31, December 31, 2020 2019 Internal sales commissions $ 15,335 $ 15,064 Third party commissions 12,820 10,845 Other 436 462 Total $ 28,591 $ 26,371

Investment in Real Estate (Tabl

Investment in Real Estate (Tables)	3 Months Ended
Investment in Real Estate (Tables)	Mar. 31, 2020
Investment in Real Estate
Summary of properties owned or leased	The following is a summary of the properties owned or leased by market at March 31, 2020 (in thousands): Buildings and Construction in Market Land Improvements Progress Total Cost Boston $ 5,154 $ 119,803 $ 3,005 $ 127,962 Chicago 5,493 115,909 110,768 232,170 Denver — 34,938 386 35,324 Los Angeles 18,672 377,134 81,178 476,984 Miami 728 14,641 — 15,369 New York 2,729 173,080 54,719 230,528 Northern Virginia 21,856 401,645 101,718 525,219 San Francisco Bay 39,961 778,380 86,020 904,361 Total $ 94,593 $ 2,015,530 $ 437,794 $ 2,547,917 The following is a summary of the properties owned or leased by market at December 31, 2019 (in thousands): Market Land Buildings and Construction in Total Cost Boston $ 5,154 $ 119,227 $ 931 $ 125,312 Chicago 5,493 115,699 100,118 221,310 Denver — 32,659 2,461 35,120 Los Angeles 18,672 376,525 60,178 455,375 Miami 728 14,491 133 15,352 New York 2,729 155,746 56,271 214,746 Northern Virginia 21,856 398,742 101,619 522,217 San Francisco Bay 39,961 776,642 72,763 889,366 Total $ 94,593 $ 1,989,731 $ 394,474 $ 2,478,798

Other Assets (Tables)

Other Assets (Tables)	3 Months Ended
Other Assets (Tables)	Mar. 31, 2020
Other Assets.
Schedule of other assets	Other assets consisted of the following, net of amortization and depreciation, if applicable for each line item, as of March 31, 2020, and December 31, 2019 (in thousands): March 31, December 31, 2020 2019 Deferred rent receivable $ 38,831 $ 38,335 Initial direct costs 28,591 26,371 Internal-use software 16,699 16,747 Prepaid expenses 12,178 7,675 Corporate furniture, fixtures and equipment 4,507 4,848 Deferred financing costs - revolving credit facility 3,076 3,148 Other 673 3,958 Total $ 104,555 $ 101,082

Leases (Tables)

Leases (Tables)	3 Months Ended
Leases (Tables)	Mar. 31, 2020
Leases
Schedule of components of lease expense	The components of lease expense were as follows (in thousands): Three Months Ended March 31, 2020 2019 Lease expense: Operating lease expense $ 6,862 $ 6,396 Variable lease expense 1,537 1,292 Rent expense $ 8,399 $ 7,688

Lease Revenue (Tables)

Lease Revenue (Tables)	3 Months Ended
Lease Revenue (Tables)	Mar. 31, 2020
Lease Revenue
Components of data center, office, light-industrial, and other lease revenue	The components of data center, office, light-industrial, and other lease revenue were as follows (in thousands): Three Months Ended March 31, 2020 2019 Lease revenue: Minimum lease revenue $ 106,441 $ 99,410 Variable lease revenue 20,836 21,069 Total lease revenue $ 127,277 $ 120,479

Debt (Tables)

Debt (Tables)	3 Months Ended
Debt (Tables)	Mar. 31, 2020
Debt
Summary of outstanding indebtedness	A summary of outstanding indebtedness as of March 31, 2020, and December 31, 2019, is as follows (in thousands): Maturity March 31, December 31, Interest Rate Date 2020 2019 Revolving credit facility (1) 2.45% and 3.01% at March 31, 2020, and December 31, 2019, respectively November 8, 2023 $ 155,500 $ 62,500 2022 Senior unsecured term loan (1) 1.76% and 2.96% at March 31, 2020, and December 31, 2019, respectively April 19, 2022 200,000 200,000 2023 Senior unsecured notes 4.19% at March 31, 2020, and December 31, 2019, respectively June 15, 2023 150,000 150,000 2024 Senior unsecured term loan (1) 2.86% and 3.44% at March 31, 2020, and December 31, 2019, respectively April 19, 2024 150,000 150,000 2024 Senior unsecured notes 3.91% at March 31, 2020, and December 31, 2019, respectively April 20, 2024 175,000 175,000 2025 Senior unsecured term loan (1) 2.32% and 2.81% at March 31, 2020, and December 31, 2019, respectively April 1, 2025 350,000 350,000 2026 Senior unsecured notes (1) 4.52% at March 31, 2020, and December 31, 2019, respectively April 17, 2026 200,000 200,000 2029 Senior unsecured notes 4.31% at March 31, 2020, and December 31, 2019, respectively April 17, 2029 200,000 200,000 Total principal outstanding ` 1,580,500 1,487,500 Unamortized deferred financing costs (8,493) (9,098) Total debt $ 1,572,007 $ 1,478,402 (1) Our Operating Partnership has in place swap agreements with respect to the term loans noted above. The interest rates presented represent the effective interest rates as of March 31, 2020, and December 31, 2019, including the impact of the interest rate swaps, which effectively fix the interest rate on a portion of our variable rate debt. We entered into three new interest rate swaps during the quarter ended March 31, 2020. See Note 8 – Derivatives and Hedging Activities.
Summary of amount of the entity's outstanding debt when such debt currently become due	The following table summarizes when our debt currently becomes due (in thousands): Year Ending December 31, 2020 $ — 2021 — 2022 200,000 2023 305,500 2024 325,000 Thereafter 750,000 Total principal outstanding 1,580,500 Unamortized deferred financing costs (8,493) Total debt, net $ 1,572,007

Derivatives and Hedging Activ_2

Derivatives and Hedging Activities (Tables)	3 Months Ended
Derivatives and Hedging Activities (Tables)	Mar. 31, 2020
Derivatives and Hedging Activities
Schedule of derivative instruments	The following table summarizes our derivative positions as of March 31, 2020, and December 31, 2019 (in thousands): Notional Amount Fair Value (Level 2) (1) March 31, December 31, Type of Effective Expiration March 31, December 31, 2020 2019 Derivative Index Strike Rate Date Date 2020 2019 $ 75,000 $ 75,000 Interest Rate Swap 1 mo. LIBOR 1.43 % 5/5/2015 5/5/2020 $ (30) $ 67 75,000 75,000 Interest Rate Swap 1 mo. LIBOR 2.72 5/5/2018 4/5/2023 (5,469) (2,819) 100,000 100,000 Interest Rate Swap 1 mo. LIBOR 1.59 11/8/2019 4/1/2025 (5,918) 55 75,000 75,000 Interest Rate Swap 1 mo. LIBOR 1.59 11/8/2019 4/1/2025 (4,439) 41 200,000 — Interest Rate Swap 1 mo. LIBOR 0.56 3/5/2020 4/19/2022 (1,104) — 75,000 — Interest Rate Swap 1 mo. LIBOR 0.61 3/5/2020 10/5/2023 (738) — 175,000 — Interest Rate Swap 1 mo. LIBOR 0.64 3/5/2020 10/1/2024 (2,075) — $ 775,000 $ 325,000 $ (19,773) $ (2,656) (1) Derivative assets are recorded at fair value in our condensed consolidated balance sheets in other assets and derivative liabilities are recorded at fair value in our condensed consolidated balance sheets in unearned revenue, prepaid rent and other liabilities. We do not net our derivative position by counterparty for purposes of balance sheet presentation and disclosure.

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	3 Months Ended
Stockholders' Equity (Tables)	Mar. 31, 2020
Stockholders' Equity
Schedule of dividends paid per share on Series A Cumulative Preferred Stock and common shares	We announced the following dividends per share on our common stock during the three months ended March 31, 2020: Declaration Date Record Date Payment Date Common Stock March 5, 2020 March 31, 2020 April 15, 2020 $ 1.22

Noncontrolling Interests - Op_2

Noncontrolling Interests - Operating Partnership (Tables)	3 Months Ended
Noncontrolling Interests - Operating Partnership (Tables)	Mar. 31, 2020
Noncontrolling Interests - Operating Partnership
Schedule of ownership interests in our Operating Partnership	March 31, 2020 December 31, 2019 Number of Units Percentage of Total Number of Units Percentage of Total CoreSite Realty Corporation 37,394,352 77.6 % 37,244,987 77.6 % Noncontrolling interests 10,769,518 22.4 10,771,658 22.4 Total 48,163,870 100.0 % 48,016,645 100.0 %

Equity Incentive Award Plan (Ta

Equity Incentive Award Plan (Tables)	3 Months Ended
Equity Incentive Award Plan (Tables)	Mar. 31, 2020
Equity Incentive Award Plan
Schedule of stock option activity	Number of Shares Weighted- Subject to Average Option Exercise Price Options outstanding, December 31, 2019 31,746 $ 19.57 Granted — — Exercised (3,210) 18.87 Forfeited — — Expired — — Options outstanding, March 31, 2020 28,536 $ 19.65
Schedule of restricted awards and RSUs	Restricted Weighted- Stock Average Fair Awards and Value at Grant Units Date Unvested balance, December 31, 2019 292,373 $ 96.44 Granted 146,582 110.73 Forfeited (4,913) 99.04 Vested (112,245) 90.76 Unvested balance, March 31, 2020 321,797 $ 104.90
Schedule of unvested PSAs and their weighted-average fair value at the date of grant	Weighted- Average Fair Performance-Based Restricted Stock Awards Value at Grant Minimum Maximum Target Date Unvested balance, December 31, 2019 34,624 171,351 102,989 $ 107.84 Granted 10,210 71,488 40,852 125.02 Performance adjustment (1) 38,047 (7,904) 15,073 — Forfeited (1,049) (4,878) (2,964) 107.63 Vested (32,524) (32,524) (32,524) 105.55 Unvested balance, March 31, 2020 49,308 197,533 123,426 $ 113.96 (1) Includes the annual adjustment for the number of PSAs earned based on our achievement of relative TSR measured versus the MSCI US REIT Index for the applicable performance periods.
Summary of assumptions used to value stock option awards	Three Months Ended March 31, 2020 2019 Expected term (in years) 2.82 2.82 Expected volatility 24.00 % 24.09 % Expected annual dividend (1) — — Risk-free rate 0.56 % 2.48 % (1) The fair value of the PSAs assumes reinvestment of dividends.

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
Earnings Per Share (Tables)	Mar. 31, 2020
Earnings Per Share
Summary of basic and diluted income per share	The following is a summary of basic and diluted net income per share (in thousands, except share and per share amounts): Three Months Ended March 31, 2020 2019 Net income attributable to common shares $ 17,848 $ 19,661 Weighted-average common shares outstanding - basic 37,335,892 36,347,781 Effect of potentially dilutive common shares: Stock options 25,298 38,921 Unvested awards 143,159 160,363 Weighted-average common shares outstanding - diluted 37,504,349 36,547,065 Net income per share attributable to common shares Basic $ 0.48 $ 0.54 Diluted $ 0.48 $ 0.54

Organization and Description _2

Organization and Description of Business (Details) - Operating partnership	Mar. 31, 2020	Dec. 31, 2019
Coresite Realty Corporation
Organization
Percentage of ownership interests held by the entity	77.60%	77.60%
Noncontrolling interests
Organization
Percentage of ownership interests held by others	22.40%	22.40%
Carlyle Group
Organization
Percentage of ownership interests held by others	22.40%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Real Estate (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Investments in Real Estate
Capitalized interest costs	$ 3.5	$ 2.6
Depreciation expense	$ 36.9	$ 32.2
Building \| Minimum
Investments in Real Estate
Useful lives	27 years
Building \| Maximum
Investments in Real Estate
Useful lives	40 years
Building Improvements \| Minimum
Investments in Real Estate
Useful lives	1 year
Building Improvements \| Maximum
Investments in Real Estate
Useful lives	10 years

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Deferred Costs & Impairment (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Summary of Significant Accounting Policies
Impairment loss related to intangible assets	$ 0	$ 0
Goodwill	40,646		$ 40,646
Impairment loss related to goodwill	0	0
Deferred Costs
Amortization of initial direct costs	3,300	3,400
Internal sales commissions	15,335		15,064
Third party commissions	12,820		10,845
Other	436		462
Total	28,591		$ 26,371
Recoverability of Long-Lived Assets
Impairment of long-lived assets	$ 0	$ 0

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Internal Use Software, RR & IT (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Internal-Use Software
Recognized impairment of internal use software	$ 0	$ 0
Operating revenues:
Allowance for doubtful accounts (in dollars)	904		$ 371
Asset Retirement and Environmental Remediation Obligations
Asset retirement and environmental remediation obligations	$ 1,700		$ 1,700
Income taxes
Minimum percentage of distribution of taxable income to qualify as REIT	90.00%
Percentage of distribution of taxable income as per company policy	100.00%
Provision for federal income taxes	$ 0
Liabilities for uncertain positions	$ 0

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Segment Information (Details)	3 Months Ended
	Mar. 31, 2020segment
Segment information
Number of reportable segments	1

Investment in Real Estate (Deta

Investment in Real Estate (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Investment in Real Estate
Land	$ 94,593	$ 94,593
Buildings and Improvements	2,015,530	1,989,731
Construction in Progress	437,794	394,474
Total investments in real estate	2,547,917	2,478,798
Boston
Investment in Real Estate
Land	5,154	5,154
Buildings and Improvements	119,803	119,227
Construction in Progress	3,005	931
Total investments in real estate	127,962	125,312
Chicago
Investment in Real Estate
Land	5,493	5,493
Buildings and Improvements	115,909	115,699
Construction in Progress	110,768	100,118
Total investments in real estate	232,170	221,310
Denver
Investment in Real Estate
Buildings and Improvements	34,938	32,659
Construction in Progress	386	2,461
Total investments in real estate	35,324	35,120
Los Angeles
Investment in Real Estate
Land	18,672	18,672
Buildings and Improvements	377,134	376,525
Construction in Progress	81,178	60,178
Total investments in real estate	476,984	455,375
Miami
Investment in Real Estate
Land	728	728
Buildings and Improvements	14,641	14,491
Construction in Progress		133
Total investments in real estate	15,369	15,352
New York
Investment in Real Estate
Land	2,729	2,729
Buildings and Improvements	173,080	155,746
Construction in Progress	54,719	56,271
Total investments in real estate	230,528	214,746
Northern Virginia
Investment in Real Estate
Land	21,856	21,856
Buildings and Improvements	401,645	398,742
Construction in Progress	101,718	101,619
Total investments in real estate	525,219	522,217
San Francisco Bay
Investment in Real Estate
Land	39,961	39,961
Buildings and Improvements	778,380	776,642
Construction in Progress	86,020	72,763
Total investments in real estate	$ 904,361	$ 889,366

Other Assets (Details)

Other Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Other Assets.
Deferred rent receivable	$ 38,831	$ 38,335
Initial direct costs	28,591	26,371
Internal-use software	16,699	16,747
Prepaid expense	12,178	7,675
Corporate furniture, fixtures and equipment	4,507	4,848
Deferred financing costs - revolving credit facility	3,076	3,148
Other	673	3,958
Total	$ 104,555	$ 101,082

Leases - (Detail)

Leases - (Detail) $ in Thousands	3 Months Ended
Leases - (Detail) $ in Thousands	Mar. 31, 2020USD ($)ft²	Mar. 31, 2019USD ($)	Dec. 31, 2019
Lease terms
Option to extend	20 years
Weighted-average remaining lease term	9 years		9 years
Weighted average discount rate - Operating leases	4.90%		4.90%
Increase in Right-of-Use Asset	$ 7,646
Increase in operating lease liability	1,000
Lease expense
Operating lease expense	6,862	$ 6,396
Variable lease expense	1,537	1,292
Rent expense	$ 8,399	$ 7,688
Minimum
Lease terms
Remaining lease terms	1 year
Maximum
Lease terms
Remaining lease terms	15 years
DC2 Washington DC
Lease terms
Net Leased Space \| ft²	25,000
Increase in Right-of-Use Asset	$ 7,000

Lease Revenue (Details)

Lease Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
Lease Revenue (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Mar. 31, 2019
Components of lease revenue
Minimum lease revenue	$ 106,441	$ 99,410
Variable lease revenue	20,836	21,069
Total lease revenue	$ 127,277	$ 120,479

Debt - Summary of Debt (Details

Debt - Summary of Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Nov. 08, 2019	Apr. 17, 2019
Debt
Total principal outstanding	$ 1,580,500	$ 1,487,500
Unamortized deferred financing costs	(8,493)	(9,098)
Total debt	$ 1,572,007	$ 1,478,402
Revolving Credit Facility
Debt
Interest rate as of reporting date (as a percent)	2.45%	3.01%
Total principal outstanding	$ 155,500	$ 62,500
2022 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Interest rate as of reporting date (as a percent)	1.76%	2.96%
Total principal outstanding	$ 200,000	$ 200,000
Senior Unsecured Term Loan 2023 \| Senior Unsecured Term Loan
Debt
Total principal outstanding	$ 150,000	$ 150,000
2023 Senior unsecured notes \| Senior Unsecured Term Loan
Debt
Interest rate as of reporting date (as a percent)	2.86%	3.44%
2023 Senior unsecured notes \| Senior Unsecured Notes
Debt
Interest rate as of reporting date (as a percent)	4.19%	4.19%
Total principal outstanding	$ 150,000	$ 150,000
2024 Senior unsecured notes
Debt
Interest rate as of reporting date (as a percent)	3.91%	3.91%
2024 Senior unsecured notes \| Senior Unsecured Notes
Debt
Total principal outstanding	$ 175,000	$ 175,000
2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Interest rate as of reporting date (as a percent)	2.32%	2.81%
Total principal outstanding	$ 350,000	$ 350,000
2026 Senior unsecured notes
Debt
Interest rate as of reporting date (as a percent)				4.52%
2026 Senior unsecured notes \| Senior Unsecured Notes
Debt
Interest rate as of reporting date (as a percent)	4.52%
Total principal outstanding	$ 200,000	200,000
2029 Senior unsecured notes \| Senior Unsecured Notes
Debt
Interest rate as of reporting date (as a percent)	4.31%
Total principal outstanding	$ 200,000	$ 200,000
Operating partnership \| 2020 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding			$ 150,000
Operating partnership \| 2021 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding			100,000
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding			150,000
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding			$ 350,000

Debt - Revolving Credit Facilit

Debt - Revolving Credit Facility (Details) $ in Thousands	Apr. 15, 2020	Nov. 08, 2019USD ($)item	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)	Nov. 07, 2019USD ($)	Apr. 19, 2017USD ($)
Debt
Total principal outstanding			$ 1,580,500	$ 1,487,500
Subsequent Event
Debt
Term of loan facility	7 years
Revolving Credit Facility
Debt
Total principal outstanding			$ 155,500	62,500
Credit Agreement
Debt
Leverage ratio (as a percent)			31.20%
Secured debt ratio, Covenant (as a percent)			0.00%
Fixed charge coverage ratio			5.8
Credit Agreement \| Minimum
Debt
Fixed charge coverage ratio			1.5
Credit Agreement \| Maximum
Debt
Leverage ratio (as a percent)			0.60%
Secured debt ratio (as a percent)			0.40%
2022 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding			$ 200,000	200,000
2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Unsecured term loan		$ 150,000
2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding			350,000	$ 350,000
Operating partnership \| Revolving Credit Facility
Debt
Maximum borrowing capacity		$ 450,000
Operating partnership \| Credit Agreement
Debt
Number of options available for extensions \| item		1
Extension fee (as a percent)		10.00%
Additional liquidity		$ 100,000
Maximum borrowing capacity		950,000			$ 850,000
Increase in accordion feature borrowing capacity		550,000			200,000
Maximum borrowing capacity including accordion feature		1,500,000			$ 950,000
Borrowing capacity at end of period			450,000
Letters of credit outstanding			6,100
Amount available for borrowing under the facility			$ 288,400
Operating partnership \| Credit Agreement \| Revolving Credit Facility
Debt
Leverage ratio (as a percent)			31.20%
Operating partnership \| Credit Agreement \| Revolving Credit Facility \| LIBOR
Debt
Interest rate margin (as a percent)			1.25%
Operating partnership \| Credit Agreement \| Revolving Credit Facility \| LIBOR \| Minimum
Debt
Interest rate margin (as a percent)			1.25%
Operating partnership \| Credit Agreement \| Revolving Credit Facility \| LIBOR \| Maximum
Debt
Interest rate margin (as a percent)			1.85%
Operating partnership \| Credit Agreement \| Revolving Credit Facility \| Base Rate \| Minimum
Debt
Interest rate margin (as a percent)			0.25%
Operating partnership \| Credit Agreement \| Revolving Credit Facility \| Base Rate \| Maximum
Debt
Interest rate margin (as a percent)			0.85%
Operating partnership \| 2020 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding		150,000
Operating partnership \| 2021 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding		100,000
Operating partnership \| 2022 Senior Unsecured Term Loan \| LIBOR
Debt
Interest rate margin (as a percent)			1.20%
Operating partnership \| 2022 Senior Unsecured Term Loan \| LIBOR \| Minimum
Debt
Interest rate margin (as a percent)			1.20%
Operating partnership \| 2022 Senior Unsecured Term Loan \| LIBOR \| Maximum
Debt
Interest rate margin (as a percent)			1.80%
Operating partnership \| 2022 Senior Unsecured Term Loan \| Base Rate \| Minimum
Debt
Interest rate margin (as a percent)			0.20%
Operating partnership \| 2022 Senior Unsecured Term Loan \| Base Rate \| Maximum
Debt
Interest rate margin (as a percent)			0.80%
Operating partnership \| 2022 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Unsecured term loan						$ 100,000
Increase in accordion feature borrowing capacity						$ 300,000
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding		$ 150,000
Leverage ratio (as a percent)			31.20%
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR
Debt
Interest rate margin (as a percent)			1.20%
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR \| Minimum
Debt
Interest rate margin (as a percent)		1.20%
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR \| Maximum
Debt
Interest rate margin (as a percent)		1.80%
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| Base Rate \| Minimum
Debt
Interest rate margin (as a percent)		20.00%
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| Base Rate \| Maximum
Debt
Interest rate margin (as a percent)		0.80%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding		$ 350,000
Unsecured term loan		$ 350,000
Leverage ratio (as a percent)			31.20%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR
Debt
Interest rate margin (as a percent)			1.20%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR \| Minimum
Debt
Interest rate margin (as a percent)		1.20%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR \| Maximum
Debt
Interest rate margin (as a percent)		1.80%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| Base Rate \| Minimum
Debt
Interest rate margin (as a percent)		0.20%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| Base Rate \| Maximum
Debt
Interest rate margin (as a percent)		0.80%

Debt - Unsecured Debt (Details)

Debt - Unsecured Debt (Details) - USD ($) $ in Thousands	Apr. 15, 2020	Nov. 08, 2019	Mar. 31, 2020	Jul. 14, 2020	May 06, 2020	Dec. 31, 2019	Jul. 17, 2019	Apr. 17, 2019	Apr. 20, 2017	Apr. 19, 2017	Jun. 15, 2016
Debt
Total principal outstanding			$ 1,580,500			$ 1,487,500
Subsequent Event
Debt
Term of loan facility	7 years
Aggregate principal amount	$ 150,000			$ 50,000	$ 100,000
2022 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding			$ 200,000			$ 200,000
Effective interest rate			1.76%			2.96%
2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Unsecured term loan		$ 150,000
2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding			$ 350,000			$ 350,000
Effective interest rate			2.32%			2.81%
2023 Senior unsecured notes \| Senior Unsecured Term Loan
Debt
Effective interest rate			2.86%			3.44%
2023 Senior unsecured notes \| Senior Unsecured Notes
Debt
Total principal outstanding			$ 150,000			$ 150,000
Effective interest rate			4.19%			4.19%
2024 Senior unsecured notes
Debt
Effective interest rate			3.91%			3.91%
2024 Senior unsecured notes \| Senior Unsecured Notes
Debt
Total principal outstanding			$ 175,000			$ 175,000
2026 Senior unsecured notes
Debt
Effective interest rate								4.52%
2026 Senior unsecured notes \| Senior Unsecured Term Loan
Debt
Unsecured term loan								$ 200,000
2026 Senior unsecured notes \| Senior Unsecured Notes
Debt
Total principal outstanding			$ 200,000			200,000
Effective interest rate			4.52%
2029 Senior unsecured notes \| Senior Unsecured Term Loan
Debt
Unsecured term loan							$ 75,000
2029 Senior unsecured notes \| Senior Unsecured Notes
Debt
Total principal outstanding			$ 200,000			$ 200,000
Effective interest rate			4.31%
Operating partnership \| 2020 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding		150,000
Operating partnership \| 2021 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding		100,000
Operating partnership \| 2022 Senior Unsecured Term Loan \| LIBOR
Debt
Interest rate margin (as a percent)			1.20%
Operating partnership \| 2022 Senior Unsecured Term Loan \| LIBOR \| Minimum
Debt
Interest rate margin (as a percent)			1.20%
Operating partnership \| 2022 Senior Unsecured Term Loan \| LIBOR \| Maximum
Debt
Interest rate margin (as a percent)			1.80%
Operating partnership \| 2022 Senior Unsecured Term Loan \| Base Rate \| Minimum
Debt
Interest rate margin (as a percent)			0.20%
Operating partnership \| 2022 Senior Unsecured Term Loan \| Base Rate \| Maximum
Debt
Interest rate margin (as a percent)			0.80%
Operating partnership \| 2022 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Unsecured term loan										$ 100,000
Increase in accordion feature borrowing capacity										300,000
Aggregate principal amount										$ 200,000
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding		$ 150,000
Leverage ratio (as a percent)			31.20%
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR
Debt
Interest rate margin (as a percent)			1.20%
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR \| Minimum
Debt
Interest rate margin (as a percent)		1.20%
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR \| Maximum
Debt
Interest rate margin (as a percent)		1.80%
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| Base Rate \| Minimum
Debt
Interest rate margin (as a percent)		20.00%
Operating partnership \| 2024 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| Base Rate \| Maximum
Debt
Interest rate margin (as a percent)		0.80%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan
Debt
Total principal outstanding		$ 350,000
Unsecured term loan		$ 350,000
Leverage ratio (as a percent)			31.20%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR
Debt
Interest rate margin (as a percent)			1.20%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR \| Minimum
Debt
Interest rate margin (as a percent)		1.20%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| LIBOR \| Maximum
Debt
Interest rate margin (as a percent)		1.80%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| Base Rate \| Minimum
Debt
Interest rate margin (as a percent)		0.20%
Operating partnership \| 2025 Senior Unsecured Term Loan \| Senior Unsecured Term Loan \| Base Rate \| Maximum
Debt
Interest rate margin (as a percent)		0.80%
Operating partnership \| 2023 Senior unsecured notes \| Senior Unsecured Notes \| Private Placement
Debt
Aggregate principal amount											$ 150,000
Stated interest rate											4.19%
Percentage of term notes that may be prepaid											100.00%
Percentage of term notes that holders have right to purchase in cash											100.00%
Percentage of term notes that holders may redeem for cash											100.00%
Operating partnership \| 2024 Senior unsecured notes \| Senior Unsecured Term Loan
Debt
Unsecured term loan									$ 175,000
Stated interest rate									3.91%
Percentage of term notes that may be prepaid									100.00%
Percentage of term notes that holders have right to purchase in cash									100.00%
Percentage of term notes that holders may redeem for cash									100.00%
Operating partnership \| 2026 Senior unsecured notes \| Senior Unsecured Term Loan
Debt
Stated interest rate								4.11%
Operating partnership \| 2026 Senior unsecured notes \| Senior Unsecured Notes
Debt
Percentage of term notes that may be prepaid								100.00%
Percentage of term notes that holders have right to purchase in cash								100.00%
Percentage of term notes that holders may redeem for cash								100.00%
Operating partnership \| 2029 Senior unsecured notes \| Senior Unsecured Term Loan
Debt
Aggregate principal amount								$ 125,000
Operating partnership \| 2029 Senior unsecured notes \| Senior Unsecured Term Loan \| Private Placement
Debt
Unsecured term loan								$ 200,000
Stated interest rate								4.31%
Operating partnership \| 2029 Senior unsecured notes \| Senior Unsecured Notes
Debt
Percentage of term notes that may be prepaid								100.00%
Percentage of term notes that holders have right to purchase in cash								100.00%
Percentage of term notes that holders may redeem for cash								100.00%

Debt - Maturities (Details)

Debt - Maturities (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Debt maturities
2022	$ 200,000
2023	305,500
2024	325,000
Thereafter	750,000
Total principal outstanding	1,580,500	$ 1,487,500
Unamortized deferred financing costs	(8,493)	(9,098)
Total debt	$ 1,572,007	$ 1,478,402

Debt - Subsequent Debt Financin

Debt - Subsequent Debt Financing (Details) - Subsequent Event - USD ($) $ in Millions	Apr. 15, 2020	Jul. 14, 2020	May 06, 2020
Debt Instrument [Line Items]
Debt Term	7 years
Aggregate principal amount	$ 150	$ 50	$ 100

Derivatives and Hedging Activ_3

Derivatives and Hedging Activities (Details) - USD ($) $ in Thousands	Apr. 15, 2020	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2021	Jul. 14, 2020	May 06, 2020	Dec. 31, 2019
Derivative instruments and hedging activities disclosures
Unrealized (loss) gain recorded in other comprehensive income		$ (17,028)	$ (4,466)
Interest expense		11,183	$ 9,498
Subsequent Event
Derivative instruments and hedging activities disclosures
Debt face amount	$ 150,000				$ 50,000	$ 100,000
Debt Term	7 years
Interest Rate Swap \| Designated as Hedging Instrument
Derivative instruments and hedging activities disclosures
Notional Amount		775,000					$ 325,000
Interest Rate Swap \| Designated as Hedging Instrument \| Cash Flow Hedging \| Forecast
Derivative instruments and hedging activities disclosures
Amount estimated to be reclassified as an increase to interest expense				$ 6,000
Interest Rate Swap \| Designated as Hedging Instrument \| Level 2
Derivative instruments and hedging activities disclosures
Fair Value		(19,773)					(2,656)
Interest rate swap expiring 5/20/2020 \| Designated as Hedging Instrument
Derivative instruments and hedging activities disclosures
Notional Amount		$ 75,000					75,000
Strike Rate		1.43%
Interest rate swap expiring 5/20/2020 \| Designated as Hedging Instrument \| Level 2
Derivative instruments and hedging activities disclosures
Fair Value		$ (30)					67
Interest rate swap expiring 4/5/2023 \| Designated as Hedging Instrument
Derivative instruments and hedging activities disclosures
Notional Amount		$ 75,000					75,000
Strike Rate		2.72%
Interest rate swap expiring 4/5/2023 \| Designated as Hedging Instrument \| Level 2
Derivative instruments and hedging activities disclosures
Fair Value		$ (5,469)					(2,819)
Interest rate swap expiring 4/1/2025 \| Designated as Hedging Instrument
Derivative instruments and hedging activities disclosures
Notional Amount		$ 100,000					100,000
Strike Rate		1.59%
Interest rate swap expiring 4/1/2025 \| Designated as Hedging Instrument \| Level 2
Derivative instruments and hedging activities disclosures
Fair Value		$ (5,918)					55
Second interest rate swap expiring 4/1/2025 \| Designated as Hedging Instrument
Derivative instruments and hedging activities disclosures
Notional Amount		$ 75,000					75,000
Strike Rate		1.59%
Second interest rate swap expiring 4/1/2025 \| Designated as Hedging Instrument \| Level 2
Derivative instruments and hedging activities disclosures
Fair Value		$ (4,439)					$ 41
Interest rate swap expiring 4/19/2022 \| Designated as Hedging Instrument
Derivative instruments and hedging activities disclosures
Notional Amount		$ 200,000
Strike Rate		0.56%
Interest rate swap expiring 4/19/2022 \| Designated as Hedging Instrument \| Level 2
Derivative instruments and hedging activities disclosures
Fair Value		$ (1,104)
Interest rate swap expiring 10/5/2023 \| Designated as Hedging Instrument
Derivative instruments and hedging activities disclosures
Notional Amount		$ 75,000
Strike Rate		0.61%
Interest rate swap expiring 10/5/2023 \| Designated as Hedging Instrument \| Level 2
Derivative instruments and hedging activities disclosures
Fair Value		$ (738)
Interest rate swap expiring 10/12024 \| Designated as Hedging Instrument
Derivative instruments and hedging activities disclosures
Notional Amount		$ 175,000
Strike Rate		0.64%
Interest rate swap expiring 10/12024 \| Designated as Hedging Instrument \| Level 2
Derivative instruments and hedging activities disclosures
Fair Value		$ (2,075)

Stockholders' Equity (Details)

Stockholders' Equity (Details) - Common Stock	Mar. 05, 2020$ / shares
Stockholders' Equity
Dividends Payable, Date of Record	Mar. 31, 2020
Common Stock dividend declared (per share)	$ 1.22

Noncontrolling Interests - Op_3

Noncontrolling Interests - Operating Partnership (Details) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020USD ($)$ / sharesshares	Dec. 31, 2019shares
Noncontrolling Interests - Operating Partnership
Redemption value of the noncontrolling interest \| $	$ 1,200,000
Closing price of the Company's stock (in dollars per share) \| $ / shares	$ 115.90
Noncontrolling Interests
Noncontrolling Interests - Operating Partnership
Reduction to noncontrolling interests in the Operating Partnership and an increase to common stock and additional paid in capital \| $	$ 11
Operating partnership
Noncontrolling Interests - Operating Partnership
Conversion ratio for common operating partnership units	1
Number of Operating Partnership Units (in shares)	48,163,870	48,016,645
Percentage of Total	100.00%	100.00%
Shares of common stock issued related to employee compensation arrangements	149,365
Quarterly distributions will receive by holders of operating partnership units (in dollars per unit) \| $ / shares	$ 1.22
Operating partnership \| Coresite Realty Corporation
Noncontrolling Interests - Operating Partnership
Number of Operating Partnership Units (in shares)	37,394,352	37,244,987
Percentage of Total	77.60%	77.60%
Operating partnership \| Noncontrolling interests
Noncontrolling Interests - Operating Partnership
Number of Operating Partnership Units (in shares)	10,769,518	10,771,658
Percentage of Total	22.40%	22.40%

Equity Incentive Plan (Details)

Equity Incentive Plan (Details) - 2010 Plan - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Equity Incentive Plan
Shares of common stock reserved for issuance	6,000,000
Shares of common stock that were available for issuance	2,474,370
Stock Options
Number of Shares Subject to Option
Options outstanding at the beginning of the period (in shares)	31,746
Exercised (in shares)	(3,210)
Options outstanding at the end of the period (in shares)	28,536
Weighted Average Exercise Price
Options outstanding at the beginning of the period (in dollars per share)	$ 19.57
Exercised (in dollars per share)	18.87
Options outstanding at the end of the period (in dollars per share)	$ 19.65
Restricted Awards
Compensation cost not yet recognized
Unearned compensation	$ 32
Restricted Awards \| Weighted Average
Compensation cost not yet recognized
Vesting period	2 years 10 months 24 days
Restricted awards
Restricted Awards and PSA's
Unvested balance at the beginning of the period (in shares)	292,373
Granted (in shares)	146,582
Forfeited (in shares)	(4,913)
Vested (in shares)	(112,245)
Unvested balance at the end of the period (in shares)	321,797
Weighted Average Fair Value at Grant
Unvested balance at the beginning of the period (in dollars per share)	$ 96.44
Granted (in dollars per share)	110.73
Forfeited (in dollars per share)	99.04
Vested (in dollars per share)	90.76
Unvested balance at the end of the period (in dollars per share)	$ 104.90
PSAs
Compensation cost not yet recognized
Unearned compensation	$ 9.6
Assumptions used to value the stock options granted
Expected term	2 years 9 months 25 days	2 years 9 months 25 days
Expected volatility (as a percent)	24.00%	24.09%
Risk-free rate (as a percent)	0.56%	2.48%
Performance period	3 years
PSAs \| Weighted Average
Weighted Average Fair Value at Grant
Unvested balance at the beginning of the period (in dollars per share)	$ 107.84
Granted (in dollars per share)	125.02
Forfeited (in dollars per share)	107.63
Vested (in dollars per share)	105.55
Unvested balance at the end of the period (in dollars per share)	$ 113.96
Compensation cost not yet recognized
Vesting period	2 years 4 months 24 days
PSAs \| Minimum
Restricted Awards and PSA's
Unvested balance at the beginning of the period (in shares)	34,624
Granted (in shares)	10,210
Performance adjustment	38,047
Forfeited (in shares)	(1,049)
Vested (in shares)	(32,524)
Unvested balance at the end of the period (in shares)	49,308
Compensation cost not yet recognized
Percentage of target number of shares for PSAs granted in years 2015, 2016 and 2017	25.00%
Assumptions used to value the stock options granted
Performance period	1 year
PSAs \| Maximum
Restricted Awards and PSA's
Unvested balance at the beginning of the period (in shares)	171,351
Granted (in shares)	71,488
Performance adjustment	(7,904)
Forfeited (in shares)	(4,878)
Vested (in shares)	(32,524)
Unvested balance at the end of the period (in shares)	197,533
Compensation cost not yet recognized
Percentage of target number of shares for PSAs granted in years 2015, 2016 and 2017	175.00%
Assumptions used to value the stock options granted
Performance period	3 years
PSAs \| Target
Restricted Awards and PSA's
Unvested balance at the beginning of the period (in shares)	102,989
Granted (in shares)	40,852
Performance adjustment	15,073
Forfeited (in shares)	(2,964)
Vested (in shares)	(32,524)
Unvested balance at the end of the period (in shares)	123,426

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Earnings Per Share
Net income attributable to common shares	$ 17,848	$ 19,661
Weighted-average common shares outstanding - basic	37,335,892	36,347,781
Effect of potentially dilutive common shares:
Weighted-average common shares outstanding - diluted	37,504,349	36,547,065
Net income per share attributable to common shares
Basic	$ 0.48	$ 0.54
Diluted	$ 0.48	$ 0.54
Weighted-average potentially dilutive securities excluded in calculation of basic and diluted income (loss) per share	2,054	39,754
Stock Options
Effect of potentially dilutive common shares:
Potentially dilutive common shares	25,298	38,921
Restricted awards
Effect of potentially dilutive common shares:
Potentially dilutive common shares	143,159	160,363

Estimated Fair Value of Finan_2

Estimated Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Estimated Fair Value of Financial Instruments
Total principal outstanding	$ 1,580,500	$ 1,487,500
Fair value of debt	$ 1,600,000	$ 1,500,000

Commitments and Contingencies (

Commitments and Contingencies (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Mar. 31, 2020
Telecommunications Capacity
Commitments and Contingencies
Open commitments		$ 75.2
Telecommunications Capacity \| Forecast
Commitments and Contingencies
Open commitments met	$ 5.7
Construction Contracts
Commitments and Contingencies
Open commitments		$ 145.7