CyrusOne (CONE) 10-Q 10 May 17 2017 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2017	Apr. 30, 2017
Document and Entity Information [Abstract]
Entity Registrant Name	CyrusOne Inc.
Entity Central Index Key	1,553,023
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q1
Trading Symbol	CONE
Amendment Flag	false
Entity Common Stock, Shares Outstanding		87,725,905

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Investment in real estate:
Land	$ 156.9	$ 142.7
Buildings and improvements	1,270.9	1,008.9
Equipment	1,438	1,042.9
Construction in progress	371.7	407.1
Subtotal	3,237.5	2,601.6
Accumulated depreciation	(625.9)	(578.5)
Net investment in real estate	2,611.6	2,023.1
Cash and cash equivalents	20.4	14.6
Rent and other receivables (net of allowance for doubtful accounts of $2.1 and $2.1 as of March 31, 2017 and December 31, 2016, respectively)	89.4	83.3
Restricted cash	0.6	0
Goodwill	455.1	455.1
Intangible assets (net of accumulated amortization of $116.0 and $110.7 as of March 31, 2017 and December 31, 2016, respectively)	223.1	150.2
Other assets	143.6	126.1
Total assets	3,543.8	2,852.4
Liabilities and equity
Accounts payable and accrued expenses	268.2	227.1
Deferred revenue	93.3	76.7
Capital lease obligations	12.4	10.8
Long-term debt, net	1,731.8	1,240.1
Lease financing arrangements	134.5	135.7
Total liabilities	2,240.2	1,690.4
Commitment and contingencies
Equity
Preferred stock, $.01 par value, 100,000,000 authorized; no shares issued or outstanding	0	0
Common stock, $.01 par value, 500,000,000 shares authorized and 87,725,494 and 83,536,250 shares issued and outstanding at March 31, 2017 and December 31, 2016, respectively	0.9	0.8
Additional paid in capital	1,620.5	1,412.3
Accumulated deficit	(316.5)	(249.8)
Accumulated other comprehensive loss	(1.3)	(1.3)
Total stockholders’ equity	1,303.6	1,162
Total liabilities and equity	$ 3,543.8	$ 2,852.4

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 2.1	$ 2.1
Accumulated amortization for intangible assets	$ 116	$ 110.7
Preferred stock par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock authorized (in shares)	100,000,000	100,000,000
Preferred stock issued (in shares)	0	0
Preferred stock outstanding (in shares)	0	0
Common stock par value (in dollars per share)	$ 0.01	$ 0.01
Common stock shares authorized (in shares)	500,000,000	500,000,000
Common stock issued (in shares)	87,725,494	83,536,250
Common stock outstanding (in shares)	87,725,494	83,536,250

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue:
Base revenue and other	$ 134.2	$ 106.5
Metered power reimbursements	15.1	11.3
Revenue	149.3	117.8
Costs and expenses:
Property operating expenses	52.3	40.3
Sales and marketing	4.9	4
General and administrative	15.8	14
Depreciation and amortization	55.7	39.3
Transaction and acquisition integration costs	0.6	2.3
Loss on disposal	0.2	0
Total costs and expenses	129.5	99.9
Operating income	19.8	17.9
Interest expense	13.6	12.1
Loss on extinguishment of debt	36.2	0
Net (loss) income before income taxes	(30)	5.8
Income tax expense	(0.4)	(0.2)
Net (loss) income attributed to common stockholders	$ (30.4)	$ 5.6
Basic weighted average common shares outstanding (in shares)	84	72.1
Diluted weighted average common shares outstanding (in shares)	84	72.8
Income (loss) per share - basic and diluted (in dollars per share)	$ (0.36)	$ 0.07
Dividends declared per share (in dollars per share)	$ 0.42	$ 0.38

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive (Loss) Income - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (30.4)	$ 5.6
Other comprehensive (loss) income:
Foreign currency translation adjustments	0	0
Comprehensive (loss) income attributable to CyrusOne Inc.	$ (30.4)	$ 5.6

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss	Total Stockholders' Equity
Beginning Balance (in shares) at Dec. 31, 2015		72.6
Beginning Balance at Dec. 31, 2015		$ 0.7	$ 967.2	$ (145.9)	$ (0.4)	$ 821.6
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ 5.6			5.6		5.6
Stock issuance costs			(0.5)			(0.5)
Stock-based compensation (in shares)		0.6
Stock-based compensation			3			3
Tax payment upon exercise of equity awards (in shares)		(0.5)
Tax payment upon exercise of equity awards			(13.6)			(13.6)
Issuance of common stock (in shares)		6.9
Issuance of common stock		$ 0.1	255.9			256
Dividends declared				(30)		(30)
Ending Balance (in shares) at Mar. 31, 2016		79.6
Ending Balance at Mar. 31, 2016		$ 0.8	1,212	(170.3)	(0.4)	1,042.1
Beginning Balance (in shares) at Dec. 31, 2016		83.5
Beginning Balance at Dec. 31, 2016		$ 0.8	1,412.3	(249.8)	(1.3)	1,162
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ (30.4)			(30.4)		(30.4)
Stock-based compensation (in shares)		(0.1)
Stock-based compensation			3.7			3.7
Tax payment upon exercise of equity awards (in shares)		(0.1)
Tax payment upon exercise of equity awards			(6.4)			(6.4)
Issuance of common stock (in shares)		4.4
Issuance of common stock		$ 0.1	210.9			211
Dividends declared				(36.3)		(36.3)
Ending Balance (in shares) at Mar. 31, 2017		87.7
Ending Balance at Mar. 31, 2017		$ 0.9	$ 1,620.5	$ (316.5)	$ (1.3)	$ 1,303.6

Condensed Consolidated Stateme7

Condensed Consolidated Statements of Equity (Parenthetical) - $ / shares	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Stockholders' Equity [Abstract]
Dividends declared per share (in dollars per share)	$ 0.42	$ 0.38

Condensed Consolidated Stateme8

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net (loss) income	$ (30.4)	$ 5.6
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation and amortization	55.7	39.3
Non-cash interest expense and change in interest accrual	(1)	0.9
Stock-based compensation expense	3.7	3
Provision for bad debt	0	0.1
Loss on extinguishment of debt	36.2	0
Loss on disposal	0.2	0
Change in operating assets and liabilities:
Rent receivables and other assets	(20)	6.2
Accounts payable and accrued expenses	(4.9)	0
Deferred revenues	15.7	(2.3)
Net cash provided by operating activities	55.2	52.8
Cash flows from investing activities:
Capital expenditures – asset acquisitions, net of cash acquired	(492.3)	(131.1)
Capital expenditures – other development	(182.5)	(78.5)
Changes in restricted cash	(0.6)	0.8
Net cash used in investing activities	(675.4)	(208.8)
Cash flows from financing activities:
Issuance of common stock	211	256
Dividends paid	(32.4)	(22.8)
Borrowings from credit facility	440	320
Payments on credit facility	(270)	(305)
Payments on senior notes	(474.8)	0
Proceeds from issuance of debt	800	0
Payments on capital leases and lease financing arrangements	(2.3)	(3.1)
Debt issuance costs	(8.8)	(2.1)
Payment of debt extinguishment costs	(30.3)	0
Tax payment upon exercise of equity awards	(6.4)	(13.6)
Net cash provided by financing activities	626	229.4
Net increase in cash and cash equivalents	5.8	73.4
Cash and cash equivalents at beginning of period	14.6	14.3
Cash and cash equivalents at end of period	20.4	87.7
Supplemental disclosures
Cash paid for interest, net of amount capitalized	18.3	6.2
Cash paid for income taxes	0	0.1
Capitalized interest	3.6	2.1
Non-cash investing and financing activities
Acquisition and development of properties in accounts payable and other liabilities	174.3	111.9
Dividends payable	37.7	31.5
Debt issuance cost payable	$ 1.5	$ 0

Description of Business

Description of Business	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business CyrusOne Inc., together with CyrusOne GP, a wholly owned subsidiary of CyrusOne Inc., through which CyrusOne Inc. wholly owns CyrusOne LP (the operating partnership) and the subsidiaries of the operating partnership (collectively, “CyrusOne”, “we”, “us”, “our”, and the “Company”) is an owner, operator and developer of enterprise-class, carrier-neutral, multi-tenant data center properties. Our customers operate in a number of industries, including information technology, financial services, energy, oil and gas, mining, medical and consumer goods and services. We currently operate 39 data centers and 2 recovery centers located in the United States, United Kingdom and Singapore.

Recent Developments

Recent Developments	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Recent Developments	Recent Developments On February 27, 2017, the Company effected a full physical early settlement of the previously announced forward sale agreements entered into with Goldman, Sachs & Co. on August 10, 2016 relating to, in the aggregate, approximately 4.4 million shares of the Company’s common stock. Upon settlement, the Company issued and sold all such shares to Goldman, Sachs & Co., in its capacity as forward purchaser, in exchange for net proceeds of approximately $210.8 million , in accordance with the provisions of the forward sales agreements. Such proceeds were used to finance, in part, the acquisition of the Sentinel Properties (as defined below). Our total stock issuance for the first quarter of 2017 was $211.0 million which included $0.2 million related to the employee stock purchase plans. On February 28, 2017 , CyrusOne closed its acquisition of two enterprise-class data centers located in Somerset, New Jersey and Raleigh-Durham, North Carolina (the Sentinel Properties) from Sentinel Data Centers. The Company paid aggregate cash consideration of approximately $492.3 million in connection therewith, including transaction related costs of $1.5 million . The transaction was financed by the Company with proceeds from settlement of its forward equity sale described above and borrowings under its Revolving Credit Facility (as defined below). On March 17, 2017, CyrusOne LP and CyrusOne Finance Corp. completed their offering of $500.0 million aggregate principal amount of 5.000% senior notes due 2024 (2024 Notes) and $300.0 million aggregate principal amount of 5.375% senior notes due 2027 (2027 Notes, and together with the 2024 Notes, the New Notes) in a private offering. The issuers have agreed to use commercially reasonable efforts to file an exchange offer registration statement with the Securities and Exchange Commission (SEC) and to have the registration statement declared effective on or prior to the 390th day after the issue date of the New Notes, and to complete an exchange offer. The Company received proceeds of $791.2 million , net of underwriting costs of $8.8 million . In addition, the Company incurred approximately $1.5 million in other costs. The 2024 Notes will mature on March 15, 2024 and the 2027 Notes will mature on March 15, 2027, in each case unless earlier redeemed or repurchased. The New Notes are guaranteed on a joint and several basis by CyrusOne Inc., CyrusOne GP and all of CyrusOne LP’s existing domestic subsidiaries (other than CyrusOne Finance Corp. and CyrusOne Government Services LLC). Each of CyrusOne LP’s restricted subsidiaries (other than any designated excluded subsidiary or receivables entity) that guarantees any other indebtedness of CyrusOne LP or other indebtedness of the guarantors will be required to guarantee the New Notes in the future. The Company used the net proceeds from the offering (i) to finance its repurchase and redemption of all of its outstanding 6.375% Senior Notes due 2022 (the 2022 Notes), of which $474.8 million in aggregate principal amount was outstanding, (ii) for the repayment of borrowings outstanding under the operating partnership’s Revolving Credit Facility and (iii) for the payment of related premiums, fees, discounts and expenses.

Basis of Presentation

Basis of Presentation	3 Months Ended
	Mar. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements as of March 31, 2017 and December 31, 2016 , and for the three months ended March 31, 2017 and March 31, 2016 , are prepared on a consolidated basis. In addition, the accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and should be read in conjunction with the financial statements and notes thereto included in our Annual Report on Form 10-K/A for the year ended December 31, 2016 , which was filed with the SEC on February 27, 2017. Certain information and footnote disclosures normally included in the condensed consolidated financial statements prepared in accordance with GAAP have been omitted from this report on Form 10-Q pursuant to the rules and regulations of the SEC. Results for the interim periods in this report are not necessarily indicative of future financial results and have not been audited by our independent registered public accounting firm. In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments necessary to present fairly our condensed consolidated financial statements as of March 31, 2017 , and for the three months ended March 31, 2017 and 2016 . These adjustments are of a normal recurring nature and consistent with the adjustments recorded to prepare the annual audited financial statements as of December 31, 2016 . All amounts reflected are in millions except share and per share data. Base revenue and other and metered power reimbursements for the three months ended March 31, 2016 have been presented separately to conform with the presentation for the three months ended March 31, 2017. There is no change to total revenue as a result of this change in presentation.

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Use of Estimates —Preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. These estimates and assumptions are based on management’s knowledge of current events and actions that we may undertake in the future. Estimates are used in determining the fair value of leased real estate, including purchase price allocations for business combinations and asset acquisitions, the useful lives of real estate and other long-lived assets, future cash flows associated with goodwill and other long-lived asset impairment testing, deferred tax assets and liabilities and loss contingencies. Actual results may differ from these estimates and assumptions. Investments in Real Estate —Investment in real estate consist of land, buildings, improvements and integral equipment utilized in our data center operations. Real estate acquired from third parties has been recorded at its acquisition cost. Additions and improvements which extend an asset’s useful life or increase its functionality are capitalized and depreciated over the asset’s remaining life. Maintenance and repairs are expensed as incurred. When we are involved in the construction of structural improvements to leased property, we are deemed the accounting owner of the leased real estate. In these instances, we bear substantially all the construction period risk, including managing or funding construction. As we have substantially all of the construction risks, we are deemed the “owner” of the asset under construction for accounting purposes during the construction period, and are therefore required to capitalize the construction costs on the accompanying consolidated balance sheets. At inception, the fair value of the building (excluding land) is recorded as an asset, and the construction and modification costs to the building that are not funded by us would be recorded as a liability. As construction progresses, the value of the asset and obligation increases by the fair value of the structural improvements. At completion of the construction, Sales-Leaseback Accounting under ASC 840-40-25 is also evaluated. Due to our continuing involvement with the lessor, Sales-Leaseback Accounting is precluded and the liability is not derecognized. When the asset is placed in service, depreciation commences, and the leased real estate is depreciated to the lesser of (i) its estimated fair value at the end of the term or (ii) the expected amount of the unamortized obligation at the end of the term. The associated obligation is presented as Lease financing arrangements in the accompanying consolidated balance sheets. When we are not deemed the accounting owner of leased real estate, we further evaluate the lease to determine whether the lease should be classified as a capital or operating lease. One of the following four characteristics must be present to classify a lease as a capital lease: (i) the lease transfers ownership of the property to the lessee by the end of the lease term, (ii) the lease contains a bargain purchase option, (iii) the lease term is equal to 75% or more of the estimated economic life of the leased property or (iv) the net present value of the lease payments is at least 90% of the fair value of the leased property. Construction in progress includes direct and indirect expenditures for the construction and expansion of our data centers and is stated at its acquisition cost. Independent contractors perform substantially all of the construction and expansion efforts of our data centers. Construction in progress includes costs incurred under construction contracts including project management services, engineering and schematic design services, design development, construction services and other construction-related fees and services. Interest, property taxes and certain labor costs are also capitalized during the construction of an asset. These costs are depreciated over the estimated useful life of the related assets. Depreciation is calculated using the straight-line method over the estimated useful life of the asset. Useful lives range from nine to thirty years for buildings, three to thirty years for building improvements, and two to twenty years for equipment. Leasehold improvements are amortized over the shorter of the asset’s useful life or the remaining lease term, including renewal options which are reasonably assured. Management reviews the carrying value of long-lived assets, including intangible assets with finite lives, when events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. Examples of such indicators may include a significant adverse change in the extent to which or manner in which the property is being used, an accumulation of costs significantly in excess of the amount originally expected for acquisition or development, or a history of operating or cash flow losses. When such indicators exist, we review an estimate of the undiscounted future cash flows expected to result from the use of an asset (or group of assets) and its eventual disposition and compare such amount to its carrying amount. We consider factors such as future operating income, leasing demand, competition and other factors. If our undiscounted net cash flows indicate that we are unable to recover the carrying value of the asset, an impairment loss is recognized. An impairment loss is measured as the amount by which the asset’s carrying value exceeds its estimated fair value. There were no impairments recognized for the three months ended March 31, 2017 and March 31, 2016 . Business Combinations and Asset Acquisitions —The Company applies the purchase method for business combinations, where all tangible and identifiable intangible assets acquired and all liabilities assumed are recorded at fair value. Any excess purchase price is recorded as goodwill. Transaction costs associated with business combinations are expensed as incurred. Revenues and the results of operations of the acquired business are included in the accompanying condensed consolidated financial statements commencing on the date of acquisition. The Company applies a screen test to determine when a set is not a business. When substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. Purchase price paid for assets acquired is allocated between identified tangible and intangible assets acquired. Transaction costs associated with asset acquisitions are capitalized. Revenues and the results of operations of the acquired assets are included in the accompanying condensed consolidated financial statements commencing on the date of the asset acquisition. 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. Restricted Cash —Restricted cash includes cash equivalents held to collateralize standby letters of credit and/or deposited in escrow to fund construction or pending potential acquisition transactions. In addition, we may have other cash that is not immediately available for use in current operations. Rent and Other Receivables —Receivables consist principally of trade receivables from customers and are generally unsecured and due within 30 to 120 days . Unbilled receivables arise from services rendered but not yet billed. Expected credit losses associated with trade receivables are recorded as an allowance for doubtful accounts. The allowance for doubtful accounts is estimated based upon historic patterns of credit losses for aged receivables as well as specific provisions for certain identifiable, potentially uncollectible balances. When internal collection efforts on accounts have been exhausted, the accounts are written-off and the associated allowance for doubtful accounts is reduced. At March 31, 2017 , and December 31, 2016 , there were no customers with receivables that made up 10% of the Company's Rent and other receivables balance. Deferred Leasing Costs —Deferred leasing costs are presented with Other assets in the accompanying consolidated balance sheets. Leasing commissions incurred at the commencement of a new lease are capitalized and amortized over the term of the customer lease. Amortization of deferred leasing costs is presented with Depreciation and amortization in the accompanying consolidated statements of operations. If a lease terminates prior to the expiration of the lease, the remaining unamortized cost is written off to amortization expense. As of March 31, 2017 and December 31, 2016 , deferred leasing costs were $24.7 million and $23.3 million , respectively. Deferred Financing Costs —Deferred financing costs include costs incurred in connection with issuance of debt, including our senior notes, term loans and revolving credit facilities. These costs include deferred financing costs associated with our revolving line of credit and are presented in the balance sheet as a direct reduction from the carrying amount of the debt liability. These financing costs are deferred and amortized to expense over the term of the instrument and are included as a component of Interest expense. Revenue Recognition —Colocation rentals are generally billed monthly in advance, and some contracts have escalating payments over the term of the contract. If rents escalate without the lessee gaining access to or control over additional leased space or power, and the lessee takes possession of, or controls the physical use of the property (including all contractually committed power) at the beginning of the lease term, the rental payments by the lessee are recognized as revenue on a straight-line basis over the term of the lease. If rents escalate because the lessee gains access to and control over additional leased space or power, revenue is recognized in proportion to the additional space or power in the periods that the lessee has control over the use of the additional space or power. The excess of revenue recognized over amounts contractually due is recognized in Other assets in the accompanying consolidated balance sheets. As of March 31, 2017 and December 31, 2016 , straight-line rent receivable was $77.3 million and $67.6 million , respectively. Revenue is recognized for services or products that are deemed separate units of accounting. When a customer makes an advance payment or they are contractually obligated to pay any amounts in advance, which is not deemed a separate unit of accounting, Deferred revenue liability is recorded. This revenue is recognized ratably over the expected term of the lease, unless the pattern of service suggests otherwise. As of March 31, 2017 and December 31, 2016, Deferred revenue was $93.3 million and $76.7 million , respectively. Some of our leases are structured on a full-service gross basis in which the customer pays a fixed amount for both colocation rent and power. Other leases provide that the customer will be billed for power based upon actual usage which is separately metered. In both cases, this revenue is presented as Revenue in the accompanying consolidated statements of operations. Power is generally billed one month in arrears, and an estimate of this revenue is accrued in the month that the associated costs are incurred. We generally are not entitled to reimbursements for real estate taxes, insurance or other operating expenses. In certain leases, we receive an administrative fee when we manage the meters for our customers. Certain customer leases require specified levels of service or performance. If we fail to meet these service levels, our customers may be eligible to receive credits on their contractual billings. These credits are recognized against revenue when an event occurs that gives rise to such credits. Customer credits were immaterial for each of the periods presented. A provision for doubtful accounts is recognized when the collection of contractual rent, straight-line rent or customer reimbursements are deemed to be uncollectible. Depreciation and Amortization Expense —Depreciation expense is recognized over the estimated useful lives of real estate applying the straight-line method. The useful life of leased real estate and leasehold improvements is the lesser of the economic useful life of the asset or the term of the lease, including optional renewal periods if renewal of the lease is reasonably assured. The residual value of leased real estate is estimated as the lesser of (i) the expected fair value of the asset at the end of the lease term or (ii) the expected amount of the unamortized liability at the end of the lease term. Estimated useful lives are periodically reviewed. Depreciation expense was $48.9 million and $33.0 million for the three months ended March 31, 2017 and 2016, respectively. Amortization expense is recognized over the estimated useful lives of finite-lived intangibles. Finite-lived intangibles include trademarks, customer relationships, favorable leasehold interests, trade names and deferred leasing costs. As of March 31, 2017 , the estimated remaining weighted average useful life of trademarks and customer relationships was 9 and 12 years, respectively. In addition, we have a favorable leasehold interest related to a land lease that is being amortized over the lease term of 51 years. The trade name is being amortized over three years. Deferred leasing costs are amortized over 3 to 5 years. Amortization expense was $6.8 million and $6.3 million for the three months ended March 31, 2017 and 2016, respectively. Transaction and Acquisition Integration Costs —Transaction costs represent incremental legal, accounting and professional fees incurred in connection with consummated and potential business combinations and integration costs post an asset acquisition. Transaction costs are expensed as incurred and do not include any recurring costs from our ongoing operations. Integration costs represent incremental costs to integrate a consummated acquisition. Income Taxes —The income tax provision consists of an amount for taxes currently payable and an amount for tax consequences deferred to future periods. CyrusOne Inc. has elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (the Code), commencing with our initial taxable year ending December 31, 2013. Provided we continue to meet the various qualification tests mandated under the Code, we are generally 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, our taxable income will be subject to federal income tax at regular corporate rates and any applicable alternative minimum tax, and we may not be able to qualify as a REIT for four subsequent taxable years. While CyrusOne Inc. and the operating partnership do not pay federal income taxes, we are still subject to foreign, state and local income taxes in the locations in which we conduct business. Our taxable REIT subsidiaries (each a TRS) are also subject to federal and state income taxes to the extent they earn taxable income. Deferred income taxes are recognized in certain entities. Deferred income taxes are provided for temporary differences in the basis between financial statement and income tax assets and liabilities. Deferred income taxes are recalculated annually at rates then in effect. Valuation allowances are recorded to reduce deferred tax assets to amounts that are more likely than not to be realized. The ultimate realization of the deferred tax assets depends upon our ability to generate future taxable income during the periods in which basis differences and other deductions become deductible and prior to the expiration of the net operating loss carryforwards. The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction as well as various foreign, state and local jurisdictions. The Company's previous tax filings are subject to normal reviews by regulatory agencies until the related statute of limitations expires. With a few exceptions, the Company is no longer subject to U.S. federal, state or local examinations for years prior to 2012, and we have no liabilities for uncertain tax positions as of March 31, 2017 . Foreign Currency Translation and Transactions —The financial position of foreign subsidiaries is translated at the exchange rates in effect at the end of the period, while revenues and expenses are translated at average rates of exchange during the period. Gains or losses from translation of foreign operations where the local currency is the functional currency are included as components of other comprehensive (loss) income. Gains or losses from foreign currency transactions are included in determining net income. Comprehensive Income (Loss) —Comprehensive income (loss) represents the change in net assets of a company from transactions and other events from nonowner sources. Comprehensive income (loss) comprises all components of net income (loss) and all components of other comprehensive income (loss). Earnings Per Share —Basic EPS includes only the weighted average number of common shares outstanding during the period. Diluted EPS includes the weighted average number of common shares and the dilutive effect of stock options, restricted stock and share unit awards outstanding during the period, when such instruments are dilutive. All outstanding unvested share-based payment awards that contain rights to nonforfeitable dividends are treated as participating in undistributed earnings with common shareholders. Awards of this nature are considered participating securities and the two-class method of computing basic and diluted EPS is applied. Stock-Based Compensation —Our board of directors adopted the 2012 Long-Term Incentive Plan (LTIP), which was amended and restated by our stockholders on May 2, 2016. The LTIP is administered by the compensation committee of the board of directors. Awards issuable under the LTIP include common stock, restricted stock, stock options and other incentive awards. See Note 9 for additional details relating to these awards. Share-based compensation expense is based on the estimated grant-date fair value. CyrusOne Inc. recognizes share-based compensation expense on a straight-line basis over the requisite service period for time-based awards and on a graded vesting basis for performance-based awards. We adopted ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting (Subtopic 718) in the fourth quarter of 2016 and elected to account for forfeitures as they occur. Prior to the adoption of this ASU, CyrusOne estimated forfeitures based on historical activity, expected employee turnover, and other qualitative factors which were adjusted for changes in estimates and award vesting. Expenses for an award are recognized by the time they become fully vested. CyrusOne Inc. uses the Black-Scholes-Merton option pricing model to calculate the fair value of stock options. This option valuation model requires the use of subjective assumptions, including the estimated fair value of the underlying common stock, the expected stock price volatility, and the expected term of the option. The estimated fair value of the underlying common stock is based on third-party valuations. Our volatility estimates are based on a peer group of companies. We estimate the expected term of the awards to be the weighted average mid-point between the vesting date and the end of the contractual term. For interim and annual periods, we use our year-to-date actual results, financial forecasts, and other available information to estimate the probability of the award vesting based on the performance metrics. Fair Value Measurements —Fair value measurements are utilized in accounting for business combinations and testing of goodwill and other long-lived assets for impairment and disclosures. Fair value of financial and non-financial assets and liabilities is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. The three-tier hierarchy for inputs used in measuring fair value, which prioritizes the inputs used in the methodologies of measuring fair value for asset and liabilities, is as follows: Level 1—Observable inputs for identical instruments such as quoted market prices; Level 2—Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs); and Level 3—Unobservable inputs that reflect our determination of assumptions that market participants would use in pricing the asset or liability. These inputs are developed based on the best information available, including our own data. Business Segments —Business segments are components of an enterprise for which separate financial information is available and regularly viewed by the chief operating decision maker to assess performance and allocate resources. Our chief operating decision maker, the Company's Chief Executive Officer, reviews our financial information on an aggregate basis. Furthermore, our data centers have similar economic characteristics and customers across all geographic locations, and our service offerings have similar production processes, deliver services in a similar manner and use the same types of facilities and similar technologies. As a result, we have concluded that we have one reportable business segment. One customer represented approximately 17% of our revenue for the quarter ended March 31, 2017. Recently Issued Accounting Standards — Accounting Standards Update (ASU) No. 2014-09 (ASU 2014-09), Revenue from Contracts with Customers (Topic 606) On May 28, 2014, the Financial Accounting Standards Board (FASB) issued ASU 2014-09, which supersedes the revenue recognition requirements in Topic 605, "Revenue Recognition" and most industry-specific guidance. The core principle of ASU 2014-09 is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. On July 9, 2015, the FASB deferred the effective date of ASU 2014-09. The new revenue standard is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017 (January 1, 2018 for CyrusOne) and allows either a full retrospective adoption to all periods presented or a modified retrospective adoption approach with the cumulative effect of initial application of the revised guidance recognized at the date of initial application. We are beginning to evaluate the adoption alternatives and the impact of ASU 2014-09 on our consolidated financial statements. Our initial evaluation is that revenue from base colocation services, which is a majority of our revenues, would not be impacted by the adoption of this standard and therefore, we are inclined to adopt the modified retrospective approach. Our initial conclusion may change when we complete our evaluation. ASU No. 2016-01 (ASU 2016-01), Financial Instruments-Overall (Subtopic 825-10) In January 2016, the FASB amended its standards related to the accounting of certain financial instruments. This amendment addresses certain aspects of recognition, measurement, presentation and disclosure. The new rules will become effective for annual and interim periods beginning after December 15, 2017. Early adoption is not permitted. We are in the process of evaluating the impact the amendment will have on the consolidated financial statements. ASU No. 2016-02 (ASU 2016-02), Leases (Topic 842) On February 25, 2016, the FASB issued ASU 2016-02. Lessees will need to recognize on their balance sheet a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). The liability will be equal to the present value of lease payments. The asset will be based on the liability, subject to adjustment, such as for initial direct costs. For income statement purposes, the FASB retained a dual model, requiring leases to be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) while finance leases will result in a front-loaded expense pattern (similar to current capital leases). Classification will be based on criteria that are largely similar to those applied in current lease accounting. The standard is effective for CyrusOne beginning January 1, 2019. Early adoption is permitted. The new standard must be adopted using a modified retrospective transition, and provides for certain practical expedients. Transition will require application of the new guidance at the beginning of the earliest comparative period presented. We are beginning to evaluate the impact of ASU 2016-02 on our consolidated financial statements and timing of adoption. ASU No. 2016-10 (ASU 2016-10), Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing (Topic 606) In April 2016, the FASB issued ASU 2016-10 in response to an issue communicated by the Transition Resource Group for Revenue Recognition (the TRG), a group which was formed by the FASB and the International Accounting Standards Board (IASB) (collectively, the Boards), whose objective is to inform the Boards of any issues that could arise with the implementation of a converged standard on recognition of revenue from contracts with customers. ASU 2016-10 does not change the core principal of the guidance in Topic 606, but adds clarification around identifying performance obligations and licensing. The amendments in this update affect the guidance in ASU 2014-09, Contracts with Customers (Topic 606), which is not yet effective, and therefore follow the same effective date and transition requirements. ASU 2014-09 is effective for CyrusOne on January 1, 2018 and allows either a full retrospective adoption to all periods presented or a modified retrospective adoption approach with the cumulative effect of initial application of the revised guidance recognized at the date of the initial application. We are currently evaluating the impact of ASU 2016-10 and ASU 2014-09 on the Company's consolidated financial statements. ASU No. 2016-12 (ASU 2016-12), Revenue from Contracts with Customers (Subtopic 606) In May 2016, the FASB issued guidance which amends certain aspects of the Board's new revenue standard, ASU 2014-09. The amendments include the collectibility of revenue, presentation of sales tax and other similar taxes collected from customers, contracts containing noncash considerations, and contract modifications and completed contracts at transition. The effective date and transition provisions are aligned with the requirements of ASU 2014-09 (as described above). We are currently evaluating the full impact of the new standard. ASU No. 2016-13 (ASU 2016-13), Measurement of Credit Losses on Financial Instruments (Subtopic 326) In June 2016, the FASB issued guidance which requires a financial asset measured at amortized cost basis to be presented at the net amount expected to be collected. The amendments affect entities holding financial assets and net investment in leases that are not accounted for at fair value through net income. The amendments affect loans, debt securities, trade receivables, net investments in leases, off-balance-sheet credit exposures, reinsurance receivables, and any other financial assets not excluded from the scope that have the contractual right to receive cash. The guidance is effective for annual periods beginning after December 15, 2019. Early adoption is permitted. We are currently evaluating the full impact of the new standard. ASU No. 2016-18 (ASU 2016-18), Restricted Cash (Subtopic 230) In November 2016, the FASB issued guidance which addresses the diversity in the classification and presentation of changes in restricted cash on the statement of cash flows. The amendment requires that a statement of cash flows explain the change during the period in the total of cash. The guidance is effective for annual periods beginning after December 15, 2017. Early adoption is permitted. We are currently evaluating the full impact of the new standard. ASU No. 2017-01 (ASU 2017-01), Business Combinations (Topic 805) In January 2017, the FASB issued guidance which clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. Under this new guidance, the Company expects most acquisitions of investment property will meet the definition of an asset and, thus, be accounted for as asset acquisitions. Consistent with existing guidance, transaction costs associated with asset acquisitions are capitalized while transaction costs associated with business combinations are expensed as incurred. The guidance is effective for annual periods beginning after December 15, 2017. Early adoption is permitted. We adopted this standard on January 1, 2017, and applied the new guidance for the acquisition of the Sentinel Properties. ASU No. 2017-04 (ASU 2017-04), Goodwill and Other (Topic 350) In January 2017, the FASB issued ASU 2017-04 in order to simplify the test for goodwill impairment by eliminating Step 2, which measures a goodwill impairment loss by comparing the implied fair value of a reporting unit's goodwill with the carrying amount of that goodwill. Under the amendments in this Update, an entity should perform its annual goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. However, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The guidance is effective for CyrusOne beginning on January 1, 2020 and early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We adopted this standard on January 1, 2017. The adoption of this standard will not have a material impact on our consolidated financial statements. ASU No. 2017-05 (ASU 2017-05), Other Income—Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20)—Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets In February 2017, the FASB issued ASU 2017-05, Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets (Topic 610-20), which requires that all entities account for the derecognition of a business in accordance with ASC 810, Consolidations, including instances in which the business is considered in substance real estate. The ASU is effective for annual periods, and interim periods therein, beginning after December 15, 2017. Early application is permitted. We are currently evaluating the full impact of the new standard.

Asset Acquisitions

Asset Acquisitions	3 Months Ended
	Mar. 31, 2017
Business Combinations [Abstract]
Asset Acquisitions	Asset Acquisitions On February 28, 2017 , CyrusOne acquired two enterprise-class data centers located in Raleigh-Durham, North Carolina and Somerset, New Jersey from Sentinel Data Centers. The Company paid aggregate cash consideration of approximately $492.3 million , including transaction related costs of $1.5 million . The transaction was financed by the Company with proceeds of approximately $210.8 million from settlement of its forward equity sale and the remaining with borrowings under its Revolving Credit Facility. This transaction provides enhanced geographic diversification, establishing a presence in the Southeast and expanding the Company's footprint in the Northeast. The two properties consist of more than 160,000 colocation square feet and approximately 21 megawatts of power capacity, with nearly 85% of the power capacity leased. The Company applied ASU No. 2017-01, Business Combinations, to this acquisition and determined that substantially all of the fair value of the gross assets was concentrated in a group of similar identifiable assets. The Company did not acquire an organized workforce or a contract that provided access to an organized workforce. As a result, the Company determined to account for the transaction as an acquisition of assets. The condensed consolidated financial statements of CyrusOne Inc. include the operating results of the Sentinel Properties from February 28, 2017, the date of acquisition. The following table summarizes the estimated fair values of all assets acquired at the date of acquisition: IN MILLIONS Net investment in real estate $ 420.3 Cash and cash equivalents 3.2 Intangible assets: Above/Below market leases 2.3 In-place leases 75.8 Other assets 2.4 Payables (5.4 ) Deferred revenue (0.9 ) Capital lease obligation (2.2 ) Net assets acquired attributable to CyrusOne Inc. 495.5 Cash acquired (3.2 ) Net cash paid at acquisition $ 492.3 On March 31, 2016 , CyrusOne LP purchased CME Group's Chicago-Aurora I data center in Aurora, Illinois for $131.1 million , including transaction related costs, in an all cash transaction. CyrusOne LP financed the purchase with proceeds of CyrusOne Inc.'s March 2016 common stock offering. The purchase enhances the geographic diversification of CyrusOne, provides access to a high quality enterprise customer base and strengthens our product portfolio. The transaction adds to CyrusOne Inc.'s existing data center platform an approximately 428,000 square-foot facility data center serving the Chicago metropolitan region. In addition, CyrusOne acquired approximately 15 acres of land directly adjacent to the data center for future development. On April 1, 2016, the CME Group entered into a 15 -year lease for data center space at the Aurora facility. The agreement is expected to enhance the range of services available to the Company and CME Group's mutual customers through connectivity, hosting and data offerings.

Long-Term Debt, Capital Lease O

Long-Term Debt, Capital Lease Obligations and Lease Financing Arrangements	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Long-Term Debt, Capital Lease Obligations and Lease Financing Arrangements	Long-Term Debt, Capital Lease Obligations and Lease Financing Arrangements Long-term debt, Capital lease obligations and Lease financing arrangements presented in the accompanying condensed consolidated financial statements consist of the following: IN MILLIONS As of March 31, 2017 December 31, 2016 Credit facilities: Revolving Credit Facility $ 405.0 $ 235.0 Term Loans 550.0 550.0 2024 Notes 500.0 — 2027 Notes 300.0 — 2022 Notes, including bond premium — 477.3 Deferred financing costs (23.2 ) (22.2 ) Long-term debt 1,731.8 1,240.1 Capital lease obligations 12.4 10.8 Lease financing arrangements 134.5 135.7 Total $ 1,878.7 $ 1,386.6 Credit Facility —On March 17, 2016, CyrusOne LP entered into a first amended and restated credit agreement (the First Amended and Restated Credit Agreement) which amended and restated in its entirety the then-existing credit agreement, as amended to such date. The First Amended and Restated Credit Agreement provided for an additional $250.0 million senior unsecured term loan facility (the Additional Term Loan) in addition to the existing $300.0 million senior unsecured term loan facility (the Initial Term Loan, and together with the Additional Term Loan, the Term Loans) and the existing $650.0 million revolving credit facility (the Revolving Credit Facility). The First Amended and Restated Credit Agreement had an accordion feature under which CyrusOne LP was permitted to request an increase in the total commitments up to an amount not to exceed $250.0 million . Deferred financing costs of $2.1 million related to this amendment and restatement were recorded. On November 21, 2016, CyrusOne LP entered into a second amended and restated credit agreement (the Second Amended and Restated Credit Agreement) which amended and restated in its entirety the First Amended and Restated Credit Agreement. The Second Amended and Restated Credit Agreement, among other things, increased the available commitments under the Revolving Credit Facility to $1.0 billion . Deferred financing costs of $6.6 million related to this amendment and restatement were recorded. The Revolving Credit Facility is scheduled to mature in November 2020 and includes a one -year extension option, which if exercised by CyrusOne LP would extend the maturity date to November 2021, subject to certain conditions. The Initial Term Loan of $300.0 million is scheduled to mature in January 2022. The Additional Term Loan of $250.0 million is scheduled to mature in September 2021. The Revolving Credit Facility currently bears interest at a rate per annum equal to LIBOR plus 1.55% and the Initial Term Loan and Additional Term Loan currently bear interest at a rate per annum equal to LIBOR plus 1.50% (the margins are subject to adjustment). As of March 31, 2017 , the interest rate for the Revolving Credit Facility and the Term Loans was 2.53% and 2.48% , respectively. As of March 31, 2017 , there were outstanding borrowings of $405.0 million on the Revolving Credit Facility and aggregate borrowings of $550.0 million on the Term Loans. In addition, the Second Amended and Restated Credit Agreement contains an accordion feature that allows CyrusOne LP to obtain up to $300.0 million in additional revolving or term loan commitments. We pay commitment fees for the unused amount of borrowings on the Revolving Credit Facility and letter of credit fees on any outstanding letters of credit. The commitment fees are equal to 0.25% per annum of the actual daily amount by which the aggregate revolving commitments exceed the sum of outstanding revolving loans and letter of credit obligations. Commitment fees related to the Second Amended and Restated Credit Agreement were $0.4 million and $0.3 million for the three months ended March 31, 2017 and 2016, respectively. At March 31, 2017 , available capacity under the Revolving Credit Facility was $586.5 million , which included $1.0 billion under the Revolving Credit Facility less outstanding borrowings of $405.0 million and letters of credit of $8.5 million . Total liquidity at March 31, 2017 was $606.9 million , which included availability of $586.5 million under the credit facility and cash equivalents of $20.4 million . 5.000% Senior Notes due 2024 and 5.375% Senior Notes due 2027 —On March 17, 2017, CyrusOne LP and CyrusOne Finance Corp. (collectively, the Issuers) completed their offering of $500.0 million aggregate principal amount of 5.000% senior notes due 2024 and $300.0 million aggregate principal amount of 5.375% senior notes due 2027 in a private offering. The Issuers have agreed to use commercially reasonable efforts to file an exchange offer registration statement with the SEC and to have the registration statement declared effective on or prior to the 390th day after the issue date of the New Notes, and to complete an exchange offer. The Company received proceeds of $791.2 million , net of underwriting costs of $8.8 million . In addition, the Company incurred approximately $1.5 million in other costs. The New Notes are senior unsecured obligations of the Issuers, which rank equally in right of payment with all existing and future unsecured senior indebtedness of the Issuers. The New Notes will be effectively subordinated in right of payment to any secured indebtedness of the Issuers to the extent of the value of the assets securing such indebtedness. The New Notes are guaranteed on a joint and several basis by CyrusOne Inc., CyrusOne GP and all of CyrusOne LP’s existing domestic subsidiaries (other than CyrusOne Finance Corp. and CyrusOne Government Services LLC). Each of CyrusOne LP’s restricted subsidiaries (other than any designated excluded subsidiary or receivables entity) that guarantees any other indebtedness of CyrusOne LP or other indebtedness of the guarantors will be required to guarantee the New Notes in the future. Each such guarantee will be a senior unsecured obligation of the applicable guarantor, ranking equally with all existing and future unsecured senior indebtedness of such guarantor and effectively subordinated to all existing and future secured indebtedness of such guarantor to the extent of the value of the assets securing that indebtedness. The New Notes will be structurally subordinated to all liabilities (including trade payables) of each subsidiary of CyrusOne LP that does not guarantee the New Notes. The 2024 Notes will bear interest at a rate of 5.000% per annum, payable semi-annually on March 15 and September 15 of each year, beginning on September 15, 2017, to persons who are registered holders of the 2024 Notes on the immediately preceding March 1 and September 1, respectively. The 2027 Notes will bear interest at a rate of 5.375% per annum, payable semi-annually on March 15 and September 15 of each year, beginning on September 15, 2017, to persons who are registered holders of the 2027 Notes on the immediately preceding March 1 and September 1, respectively. The 2024 Notes will mature on March 15, 2024. However, prior to March 15, 2020, the Issuers may, at their option, redeem some or all of the 2024 Notes at a redemption price equal to 100% of the principal amount of the 2024 Notes, together with accrued and unpaid interest and additional interest, if any, plus a “make-whole” premium. On or after March 15, 2020, the Issuers may, at their option, redeem some or all of the 2024 Notes at any time at declining redemption prices equal to (i) 102.500% beginning on March 15, 2020, (ii) 101.250% beginning on March 15, 2021 and (iii) 100.000% beginning on March 15, 2022 and thereafter, plus, in each case, accrued and unpaid interest and additional interest, if any, to the applicable redemption date. In addition, before March 15, 2020, and subject to certain conditions, the Issuers may, at their option, redeem up to 40% of the aggregate principal amount of 2024 Notes with the net proceeds of certain equity offerings at 105.000% of the principal amount thereof, plus accrued and unpaid interest and additional interest, if any, to the date of redemption; provided that (i) at least 55% of the aggregate principal amount of 2024 Notes remains outstanding and (ii) the redemption occurs within 90 days of the closing of any such equity offering. The 2027 Notes will mature on March 15, 2027. However, prior to March 15, 2022, the Issuers may, at their option, redeem some or all of the 2027 Notes at a redemption price equal to 100% of the principal amount of the 2027 Notes, together with accrued and unpaid interest and additional interest, if any, plus a “make-whole” premium. On or after March 15, 2022, the Issuers may, at their option, redeem some or all of the 2027 Notes at any time at declining redemption prices equal to (i) 102.688% beginning on March 15, 2022, (ii) 101.792% beginning on March 15, 2023, (iii) 100.896% beginning on March 15, 2024 and (iv) 100.000% beginning on March 15, 2025 and thereafter, plus, in each case, accrued and unpaid interest and additional interest, if any, to the applicable redemption date. In addition, before March 15, 2020, and subject to certain conditions, the Issuers may, at their option, redeem up to 40% of the aggregate principal amount of 2027 Notes with the net proceeds of certain equity offerings at 105.375% of the principal amount thereof, plus accrued and unpaid interest and additional interest, if any, to the date of redemption; provided that (i) at least 55% of the aggregate principal amount of 2027 Notes remains outstanding and (ii) the redemption occurs within 90 days of the closing of any such equity offering. Deferred financing costs of $10.3 million related to the notes were recorded. 6.375% Senior Notes due 2022 —On November 20, 2012, CyrusOne LP and CyrusOne Finance Corp. (Issuers) issued $525.0 million of 6.375% senior notes due 2022 (the 2022 Notes). In March 2017, the Company repurchased all of its 2022 Notes with an aggregate face value of $474.8 million for total consideration of $515.1 million , including accrued and unpaid interest of $10.3 million . Deferred financing costs, bond premium and legal fees related to the 2022 Notes of $6.2 million were written off which resulted in a loss on extinguishment of debt of $36.2 million . Debt Covenants —The Second Amended and Restated Credit Agreement requires us to maintain certain financial covenants including the following, in each case on a consolidated basis: • A minimum fixed charge ratio; • Maximum total and secured leverage ratios; • A minimum tangible net worth requirement; • A maximum secured recourse indebtedness ratio; • A minimum unencumbered debt yield ratio; and • A maximum ratio of unsecured indebtedness to unencumbered asset value. Notwithstanding these limitations, we will be permitted, subject to the terms and conditions of the Second Amended and Restated Credit Agreement, to distribute to our stockholders cash dividends in an amount not to exceed 95% of our Funds From Operations (FFO), as defined in the Second Amended and Restated Credit Agreement for any period. The Company’s most restrictive covenants are generally included in the Second Amended and Restated Credit Agreement. In order to continue to have access to amounts available to it under the Second Amended and Restated Credit Agreement, the Company must remain in compliance with all covenants. The indentures governing the 2024 Notes and the 2027 Notes contain affirmative and negative covenants customarily found in indebtedness of this type, including a number of covenants that, among other things, restrict, subject to certain exceptions, the Company’s ability to: incur secured or unsecured indebtedness; pay dividends or distributions on its equity interests, or redeem or repurchase equity interests of the Company; make certain investments or other restricted payments; enter into transactions with affiliates; enter into agreements limiting the ability of the operating partnership’s subsidiaries to pay dividends or make certain transfers and other payments to the operating partnership or to other subsidiaries; sell assets; and merge, consolidate or transfer all or substantially all of the operating partnership’s property and assets. Notwithstanding the foregoing, the covenants contained in the indentures do not restrict the Company’s ability to pay dividends or distributions to stockholders to the extent (i) no default or event of default exists or is continuing under the indentures and (ii) the Company believes in good faith that we qualify as a REIT under the Code and the payment of such dividend or distribution is necessary either to maintain its status as a REIT or to enable it to avoid payment of any tax that could be avoided by reason of such dividend or distribution. The Company and its subsidiaries are also required to maintain total unencumbered assets of at least 150% of their unsecured debt on a consolidated basis, subject to certain qualifications set forth in the indentures. As of March 31, 2017 , we believe we were in compliance with all covenants. Deferred financing costs —Deferred financing costs are costs incurred in connection with obtaining long-term financing. Deferred financing costs were incurred in connection with the issuance of the Revolving Credit Facility, the Initial Term Loan, the Additional Term Loan and the New Notes. As of March 31, 2017 and December 31, 2016 , deferred financing costs totaled $23.2 million and $22.2 million , respectively. Amortization of deferred financing costs, included in Interest expense in the consolidated statements of operations totaled $1.0 million and $0.9 million for the three months ended March 31, 2017 and 2016 , respectively. Capital lease obligations —We use leasing as a source of financing for certain of our data center facilities and related equipment. We currently operate eight data center facilities under leases recognized as capital leases. We have options to extend the initial lease term on all but one of these leases. Lease financing arrangements —Lease financing arrangements represent leases of real estate in which we are involved in the construction of structural improvements to develop buildings into data centers. When we bear substantially all the construction period risk, such as managing or funding construction, we are deemed to be the accounting owner of the leased property and, at the lease inception date, we are required to record at fair value the property and associated liability on our balance sheet. These transactions generally do not qualify for sale-leaseback accounting due to our continued involvement in these data center operations. Interest expense on Capital lease obligations and Lease financing arrangements was $2.3 million and $2.4 million for the three months ended March 31, 2017 and 2016 , respectively.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments Fair value measurements are utilized in accounting for business combinations and testing of goodwill and other long-lived assets for impairment and disclosures. Fair value of financial and non-financial assets and liabilities is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date under current market conditions. The three-tier hierarchy for inputs used in measuring fair value, which prioritizes the inputs used in the methodologies of measuring fair value for assets and liabilities, is as follows: Level 1—Observable inputs for identical instruments such as quoted market prices; Level 2—Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs); and Level 3—Unobservable inputs that reflect our determination of assumptions that market participants would use in pricing the asset or liability. These inputs are developed based on the best information available, including our own data. The fair value of Cash and cash equivalents, Restricted cash, Rent and other receivables, Accounts payable and accrued expenses approximate their carrying value because of the short-term nature of these instruments. The carrying value and fair value of other financial instruments are as follows: IN MILLIONS As of March 31, 2017 December 31, 2016 Carrying Value Fair Value Carrying Value Fair Value 2024 Notes $ 500.0 $ 511.3 $ — $ — 2027 Notes 300.0 303.8 — — 2022 Notes — — 477.3 502.1 Revolving Credit Facility and Term Loans 955.0 955.0 785.0 785.0 The fair values of our 2024 Notes and 2027 Notes as of March 31, 2017 and our 2022 Notes as of December 31, 2016 were based on the quoted market prices for these notes, which is considered Level 1 of the fair value hierarchy. The carrying value of the Revolving Credit Facility, the Initial Term Loan and the Additional Term Loan approximates estimated fair value as of March 31, 2017 and December 31, 2016, due to the variability of interest rates and the stability of our credit ratings. These fair value measurements are considered Level 3 of the fair value hierarchy.

Dividends

Dividends	3 Months Ended
	Mar. 31, 2017
Stockholders' Equity Note [Abstract]
Dividends	Dividends On February 22, 2017 , we announced a regular cash dividend of $0.42 per common share payable to stockholders of record at the close of business on March 31, 2017 . The dividends were paid on April 13, 2017 .

Stock-Based Compensation Plans

Stock-Based Compensation Plans	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans Stock-based compensation expense was as follows: IN MILLIONS Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Founders $ — $ 0.3 2013 Grants — 0.1 2014 Grants 0.1 0.3 2015 Grants 0.8 1.1 2016 Grants 1.9 1.2 2017 Grants 0.9 — Total $ 3.7 $ 3.0 The board of directors of CyrusOne Inc. adopted the 2012 Long-Term Incentive Plan (LTIP), which was amended and restated on May 2, 2016. The LTIP is administered by the compensation committee of the board of directors. Awards issuable under the LTIP include common stock, restricted stock, stock options and other incentive awards. CyrusOne Inc. has reserved a total of 8.9 million shares of CyrusOne Inc. common stock for issuance pursuant to the LTIP, which may be adjusted for changes in capitalization and certain corporate transactions. To the extent that an award, if forfeitable, expires, terminates or lapses, or an award is otherwise settled in cash without the delivery of shares of common stock to the participant, then any unpaid shares subject to the award will be available for future grant or issuance under the LTIP. 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 LTIP. The related stock compensation expense incurred by CyrusOne Inc. is allocated to the operating partnership. Shares available under the LTIP at March 31, 2017 , were approximately 5.9 million . Shares vest according to each agreement and as long as the employee remains employed with the Company. The Company uses the Black-Scholes option-pricing model for time and performance-based options and a Monte Carlo simulation for market-based awards. The fair values of these awards use assumptions such as volatility, risk-free interest rate, and expected term of the awards. Compensation expense is measured based on the estimated grant-date fair value. Expense for time-based grants is recognized under a straight-line method. For market-based grants, expense is recognized under a graded expense attribution method. For performance-based grants, expense is recognized under a graded expense attribution method if it is probable that the performance targets will be achieved. Any dividends declared with respect to the performance and market-based shares shall be accrued by the Company and distributed on the vesting date provided that the applicable performance goal has been attained. In March 2016, the FASB issued guidance which simplifies several aspects of the accounting for employee share-based payment transactions for both public and nonpublic entities, including the accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The Company adopted the guidance in the fourth quarter of 2016 and elected the actual forfeiture rate, which had an immaterial impact to our financial statements. Founders Grants On January 24, 2013, the Company granted 1.0 million shares of time-based restricted stock, which had an aggregate value of $19.0 million on the grant date. Holders of the restricted stock have all of the rights and privileges of stockholders including but not limited to the right to vote, receive dividends and distributions upon liquidation of CyrusOne. These shares vested on January 24, 2016 . 2013 Grants On April 17, 2013, the Company issued performance and market-based awards under the LTIP in the form of stock options and restricted stock. For these awards, vesting was tied 50% to the achievement of a non-GAAP performance measure (cumulative EBITDA targets, as defined in the agreement), over the 2013-2015 performance period, and 50% market-based performance measure (the total stockholder return (TSR), as defined in the agreement) at the end of the three -year period ending December 31, 2015. The portion of the awards tied to cumulative EBITDA vested annually over a three -year period based on the Company attaining predetermined cumulative EBITDA targets. The portion of the awards tied to TSR vested at the end of three years based on TSR, during the three -year measurement period following the grant date, meeting or exceeding the return of the MSCI US REIT Index (REIT Index) over the same period. The stock option awards have a contractual life of 10 years from the award date and were granted with an exercise price equal to $23.58 . The holders of restricted stock have all of the rights and privileges of shareholders including the right to vote. As of March 31, 2017 , there was no unearned compensation as all awards are fully vested. 2014 Grants On February 7, 2014, the Company issued performance and market-based awards under the LTIP in the form of restricted stock units. For these awards, vesting was tied 50% to the achievement of a non-GAAP performance measure (cumulative Adjusted EBITDA targets, as defined in the agreement) over the 2014-2016 performance period, and 50% to a market-based performance measure TSR, as defined in the agreement, as of the end of the three -year period ending December 31, 2016. The portion of the awards tied to cumulative Adjusted EBITDA vested annually over a three -year period based on the Company attaining predetermined cumulative Adjusted EBITDA targets and as long as the employee remained employed with the Company. The portion of the award tied to TSR vested at the end of three years based on the cumulative TSR over a three -year performance period. The market and performance-based awards vested based on the same scales as the awards granted during 2013. The holders of restricted stock have all of the rights and privileges of shareholders including the right to vote. As of March 31, 2017 , there was no unearned compensation as all awards are fully vested. 2015 Grants On February 10, 2015, the Company issued awards under the LTIP in the form of options and restricted stock. The stock options are time-based and vest annually on a pro-rata basis over three years. Twenty percent of the restricted stock awards are subject to time-based vesting and eighty percent of the restricted stock awards are equally split between performance-based and market-based vesting. The performance-based metric is return on assets, which is a non-GAAP measure that is defined in the award agreement. The time-based restricted stock will vest pro-rata annually over three years. The performance and market-based restricted stock will vest annually based upon the achievement of certain criteria for each year of the three -year measurement period. The first two years are capped at 100% of the target with a cumulative true-up in year three. The market and performance-based awards will vest based on the same scales as the awards granted during 2014. The holders of restricted stock have all of the rights and privileges of shareholders including the right to vote. As of March 31, 2017 , the unearned compensation of the awards granted in 2015 totaled $1.8 million and the weighted average vesting period was 0.4 years. 2016 Grants On February 1, 2016, the Company issued shares of time, performance and market-based awards under the LTIP in the form of restricted stock. The grant date fair value of time and performance-based restricted shares was $36.99 . The grant date fair value of market-based restricted shares was $43.66 . The Company issued stock options on February 1, 2016. The stock option awards have a contractual life of 10 years from the award date and were granted with an exercise price equal to $36.99 . The Company issued options with a grant date fair value of $6.99 . The performance-based metric is return on assets, which is a non-GAAP measure and is defined in the award agreement. The time-based restricted stock awards generally vest pro-rata annually over a three -year period. The performance and market-based restricted stock awards vest annually based upon the achievement of certain criteria for each of the three -year measurement periods. The first two years are capped at 100% of the target with a cumulative true-up in year three. Certain employees were also awarded time-based restricted stock that cliff vest at the end of three years. The stock options are time-based and vest annually on a pro-rata basis over three years. The market and performance-based awards will vest based on the same scales as the awards granted during 2015. The holders of restricted stock have all of the rights and privileges of shareholders including the right to vote. As of March 31, 2017 , unearned compensation representing the unvested portion of the awards granted in 2016 totaled $12.7 million , with a weighted average vesting period of 1.4 years. 2017 Grants On February 13, 2017, the Company issued time and market-based awards under the LTIP in the form of restricted stock units and restricted stock, with a grant date fair value of $14.8 million . The Company granted 119,218 time-based restricted stock units and 18,179 shares of time-based restricted stock with a grant date fair value of $48.13 , and 129,146 market-based restricted stock units with a grant date fair value of $63.23 . The market-based metric is TSR, which is a non-GAAP measure and is the shareholder return compared to the REIT Index and is defined in the award agreement. The time-based restricted stock units generally vest pro-rata annually over a three -year period. The time-based restricted stock generally vests over a one -year period. The market-based restricted stock units generally vest annually based upon the achievement of certain criteria for each of the three -year measurement periods. The first two years are capped at 100% of the target. If at the end of the third year total performance over the three -year period exceeds the REIT Index by more than 2% , up to 200% of these awards may vest. The market-based awards will vest based on the same scales as the awards granted during 2016. The holders of restricted stock have all the rights and privileges of shareholders including the right to vote. The holders of restricted stock units do not have all of the rights and privileges of shareholders and do not have the right to vote. These rights will be acquired upon the settlement of the restricted stock units and the issuance of shares. The time-based restricted stock units have the right to receive dividends that are payable within ten days following the date the dividends are payable to shareholders. Market-based restricted stock units accrue dividends which are paid upon the settlement of the units. As of March 31, 2017 , unearned compensation representing the unvested portion of the awards granted in 2017 totaled $13.9 million , with a weighted average vesting period of 2.3 years.

(Loss) Income per Share

(Loss) Income per Share	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
(Loss) Income per Share	(Loss) Income per Share Basic (loss) income per share is calculated using the weighted average number of shares of common stock outstanding during the period. In addition, net (loss) income applicable to participating securities and the participating securities are both excluded from the computation of basic (loss) income per share. Diluted (loss) income per share is calculated using the weighted average number of shares of common stock outstanding during the period, including restricted stock outstanding. If there is net income during the period, the dilutive impact of common stock equivalents outstanding would also be reflected. The following table reflects the computation of basic and diluted net (loss) income per share for the three months ended March 31, 2017 and 2016 : IN MILLIONS, except per share amounts Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Basic Diluted Basic Diluted Numerator: Net (loss) income attributed to common stockholders $ (30.4 ) $ (30.4 ) $ 5.6 $ 5.6 Less: Restricted stock dividends (0.2 ) (0.2 ) (0.2 ) (0.2 ) Net (loss) income available to stockholders $ (30.6 ) $ (30.6 ) $ 5.4 $ 5.4 Denominator: Weighted average common outstanding-basic 84.0 84.0 72.1 72.1 Performance-based restricted stock and units — 0.6 Convertible securities — 0.1 Weighted average shares outstanding-diluted 84.0 72.8 EPS: Net (loss) income per share-basic $ (0.36 ) $ 0.07 Effect of dilutive shares: Net (loss) income per share-diluted $ (0.36 ) $ 0.07

Related Party Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions CBI Prior to November 20, 2012, CyrusOne Inc., CyrusOne GP, CyrusOne LP and its subsidiaries were operated by CBI. The condensed consolidated financial statements reflect the following transactions with CBI and its affiliated entities, including Cincinnati Bell Telephone (CBT) and Cincinnati Bell Technology Solutions (CBTS). Since December 31, 2016 , CBI has owned less than 5.0% of the outstanding common stock of CyrusOne Inc. and no operating partnership units. Revenues —The Company records revenues from CBI under contractual service arrangements. These services include leasing of data center space, power and cooling in certain of our data center facilities, network interface services and office space. Operating Expenses —The Company records expenses from CBI incurred in relation to network support, services calls, monitoring and management, storage and backup, IT systems support, and connectivity services. Total revenues were $5.3 million for the three months ended March 31, 2016 . Total operating costs and expenses were $0.5 million for the three ended March 31, 2016 .

Income Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes CyrusOne Inc. elected to be taxed as a REIT under the Code, commencing with our taxable year ended December 31, 2013. To remain qualified 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 continue to qualify for taxation as a REIT, we are generally not subject to corporate level federal income tax on the earnings distributed currently to our stockholders. 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 financial statements for federal income taxes with regards to activities of CyrusOne Inc. and its subsidiary pass-through entities. We have elected to designate two subsidiaries as taxable REIT subsidiaries (each a TRS). A TRS may perform services for our tenants that would otherwise be considered impermissible for REITs. The income generated from these services is taxed at federal and state corporate rates. While CyrusOne Inc. and the operating partnership do not pay federal income taxes, we are still subject to foreign, state, and local income taxes in the locations in which we conduct business. Income tax expense was $0.4 million for the three months ended March 31, 2017 and $0.2 million for the three months ended March 31, 2016 . For certain entities we calculate deferred tax assets and liabilities for temporary differences in the basis between financial statement and income tax assets and liabilities. Deferred income taxes are recalculated annually at rates then in effect. Valuation allowances are recorded to reduce deferred tax assets to amounts that are more likely than not to be realized. The ultimate realization of the deferred tax assets depends upon our ability to generate future taxable income during the periods in which basis differences and other deductions become deductible and prior to the expiration of the net operating loss carryforwards. Deferred tax assets (net of valuation allowance) and liabilities were accrued, as necessary, for the periods ended March 31, 2017 and December 31, 2016 . Historically, we have recorded a full valuation allowance on our foreign net deferred tax assets related to our foreign generated net operating losses due to the uncertainty of their realization. In 2013 and 2014, management determined it was necessary to record a full valuation allowance on all of our domestic and foreign net deferred tax assets due to the uncertainty of their realization. Accordingly, at March 31, 2017 and December 31, 2016 , the net domestic and foreign deferred tax assets were zero .

Guarantors

Guarantors	3 Months Ended
	Mar. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Guarantors	Guarantors CyrusOne LP and CyrusOne Finance Corp., as “LP Co-issuer” and “Finance Co-issuer,” respectively, had $500.0 million aggregate principal amount of their 2024 Notes and $300.0 million aggregate principal amount of their 2027 Notes outstanding at March 31, 2017 . As of March 31, 2017 , the New Notes are fully and unconditionally and jointly and severally guaranteed on a senior basis by CyrusOne Inc. (Parent Guarantor), CyrusOne GP (General Partner), and CyrusOne LP’s wholly owned domestic subsidiaries, CyrusOne LLC, CyrusOne TRS Inc., CyrusOne Foreign Holdings LLC, Cervalis Holdings LLC, Cervalis LLC, CyrusOne-NJ LLC and CyrusOne-NC LLC (such subsidiaries, together the Guarantor Subsidiaries). Non-Guarantor Subsidiaries consist of wholly owned subsidiaries organized outside of the United States, as well as CyrusOne Government Services LLC, a Delaware limited liability company and a wholly owned subsidiary of CyrusOne LP, and the Finance Co-Issuer. None of the Non-Guarantor Subsidiaries guarantee the New Notes. Subject to the provisions of the indentures governing the New Notes, in certain circumstances, a Guarantor may be released from its guarantee obligation, including: • upon the sale or other disposition (including by way of consolidation or merger) of such Guarantor or of all of the capital stock of such Guarantor such that such Guarantor is no longer a restricted subsidiary under the indentures, • upon the sale or disposition of all or substantially all of the assets of the Guarantor, • upon the LP Co-issuer designating such Guarantor as an unrestricted subsidiary under the terms of the indentures, • if such Guarantor is no longer a guarantor or other obligor of any other indebtedness of the LP Co-issuer or the Parent Guarantor, and • upon the defeasance or discharge of the New Notes in accordance with the terms of the indentures. The entity structure of each Issuer and guarantor of the New Notes is described below. CyrusOne Inc. – CyrusOne Inc. is the Parent Guarantor and became a registrant with the SEC upon completion of its IPO on January 24, 2013. CyrusOne GP – CyrusOne GP is the general partner and 1% owner of CyrusOne LP and has no other assets or operations. Issuers – The Issuers are CyrusOne LP and CyrusOne Finance Corp. CyrusOne Finance Corp., a wholly owned subsidiary of CyrusOne LP, was formed for the sole purpose of acting as co-issuer of the notes and has no other assets or operations. CyrusOne LP, in addition to being the co-issuer of the New Notes, is also the 100% owner, either directly or indirectly, of the Guarantor Subsidiaries and Non-Guarantor Subsidiaries. Guarantor Subsidiaries – The guarantors of the New Notes include CyrusOne LLC, CyrusOne TRS Inc., CyrusOne Foreign Holdings LLC, Cervalis Holdings LLC, Cervalis LLC, CyrusOne-NJ LLC and CyrusOne-NC LLC (the Guarantor Subsidiaries), which agreed to provide unconditional guarantees of the issuers’ obligations under the New Notes. The guarantee of each Guarantor Subsidiary is (i) a senior unsecured obligation of such Guarantor Subsidiary, (ii) pari passu in right of payment with any existing and future unsecured senior indebtedness of such Guarantor Subsidiary, (iii) senior in right of payment to any future subordinated indebtedness of such Guarantor Subsidiary and (iv) effectively subordinated in right of payment to all existing and future secured indebtedness of such Guarantor Subsidiary, to the extent of the value of the collateral securing that indebtedness. CyrusOne LLC, together with CyrusOne Foreign Holdings LLC, directly or indirectly owns 100% of the Non-Guarantor Subsidiaries. Non-Guarantor Subsidiaries consist of wholly owned subsidiaries which conduct operations in the United Kingdom and Singapore, as well as CyrusOne Government Services LLC, a Delaware limited liability company and wholly owned subsidiary of CyrusOne LP, and the Finance Co-Issuer. The following schedules present the balance sheets as of March 31, 2017 and December 31, 2016 , and the statements of operations and comprehensive (loss) income for the three months ended March 31, 2017 and March 31, 2016 , and the statements of cash flows for the three months ended March 31, 2017 and March 31, 2016 for the Parent Guarantor, General Partner, LP Co-issuer, Finance Co-issuer, Guarantor Subsidiaries and Non-Guarantor Subsidiaries. The consolidating statements of cash flows for the three months ended March 31, 2016 includes the purchase of CME in March 2016. The consolidating statements of cash flows for the three months ended March 31, 2017 includes the purchase of the Sentinel Properties on February 28, 2017. The results for the CME and Sentinel Properties purchases are included in the Guarantor Subsidiaries financial statements subsequent to the respective acquisitions. Consolidating Balance Sheets IN MILLIONS As of March 31, 2017 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Land $ — $ — $ — $ — $ 156.9 $ — $ — $ 156.9 Buildings and improvements — — — — 1,234.8 34.8 1.3 1,270.9 Equipment — — — — 1,431.6 1.0 5.4 1,438.0 Construction in progress — — — — 369.4 — 2.3 371.7 Subtotal — — — — 3,192.7 35.8 9.0 3,237.5 Accumulated depreciation — — — — (618.1 ) (7.8 ) — (625.9 ) Net investment in real estate — — — — 2,574.6 28.0 9.0 2,611.6 Cash and cash equivalents — — — — 18.1 2.3 — 20.4 Investment in subsidiaries 1,316.1 13.2 1,609.3 — 1.6 — (2,940.2 ) — Restricted cash — — — — 0.6 — — 0.6 Rent and other receivables, net — — — — 88.0 1.4 — 89.4 Intercompany receivable 16.2 — 1,459.1 — — 0.5 (1,475.8 ) — Goodwill — — — — 455.1 — — 455.1 Intangible assets, net — — — — 223.1 — — 223.1 Other assets — — — — 141.1 2.5 — 143.6 Total assets $ 1,332.3 $ 13.2 $ 3,068.4 $ — $ 3,502.2 $ 34.7 $ (4,407.0 ) $ 3,543.8 Accounts payable and accrued expenses $ 37.7 $ — $ 4.3 $ — $ 224.5 $ 1.7 $ — $ 268.2 Deferred revenue — — — — 92.6 0.7 — 93.3 Intercompany payable — — 16.2 — 1,459.6 — (1,475.8 ) — Capital lease obligations — — — — 7.2 5.2 — 12.4 Long-term debt, net — — 1,731.8 — — — — 1,731.8 Lease financing arrangements — — — — 109.0 25.5 — 134.5 Total liabilities 37.7 — 1,752.3 — 1,892.9 33.1 (1,475.8 ) 2,240.2 Total stockholders' equity 1,294.6 13.2 1,316.1 — 1,609.3 1.6 (2,931.2 ) 1,303.6 Total liabilities and equity $ 1,332.3 $ 13.2 $ 3,068.4 $ — $ 3,502.2 $ 34.7 $ (4,407.0 ) $ 3,543.8 IN MILLIONS As of December 31, 2016 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Land $ — $ — $ — $ — $ 142.7 $ — $ — $ 142.7 Buildings and improvements — — — — 973.6 34.1 1.2 1,008.9 Equipment — — — — 1,036.8 1.0 5.1 1,042.9 Construction in progress — — — — 406.4 — 0.7 407.1 Subtotal — — — — 2,559.5 35.1 7.0 2,601.6 Accumulated depreciation — — — — (571.3 ) (7.2 ) — (578.5 ) Net investment in real estate — — — — 1,988.2 27.9 7.0 2,023.1 Cash and cash equivalents — — — — 13.4 1.2 — 14.6 Investment in subsidiaries 1,170.3 11.7 1,376.1 — 2.0 — (2,560.1 ) — Rent and other receivables, net — — — — 81.8 1.5 — 83.3 Intercompany receivable 18.6 — 1,057.7 — — 0.5 (1,076.8 ) — Goodwill — — — — 455.1 — — 455.1 Intangible assets, net — — — — 150.2 — — 150.2 Other assets — — — — 123.4 2.7 — 126.1 Total assets $ 1,188.9 $ 11.7 $ 2,433.8 $ — $ 2,814.1 $ 33.8 $ (3,629.9 ) $ 2,852.4 Accounts payable and accrued expenses $ 33.9 $ — $ 4.8 $ — $ 187.7 $ 0.7 $ — $ 227.1 Deferred revenue — — — — 76.0 0.7 — 76.7 Intercompany payable — — 18.6 — 1,058.2 — (1,076.8 ) — Capital lease obligations — — — — 5.6 5.2 — 10.8 Long-term debt, net — — 1,240.1 — — — — 1,240.1 Lease financing arrangements — — — — 110.5 25.2 — 135.7 Total liabilities 33.9 — 1,263.5 — 1,438.0 31.8 (1,076.8 ) 1,690.4 Total stockholders' equity 1,155.0 11.7 1,170.3 — 1,376.1 2.0 (2,553.1 ) 1,162.0 Total liabilities and equity $ 1,188.9 $ 11.7 $ 2,433.8 $ — $ 2,814.1 $ 33.8 $ (3,629.9 ) $ 2,852.4 Consolidating Statements of Operations and Comprehensive Income (Loss) IN MILLIONS Three Months Ended March 31, 2017 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/ Consolidations Total Revenue: Base revenue and other $ — $ — $ — $ — $ 133.3 $ 0.9 $ — $ 134.2 Metered power reimbursements — — — — 14.8 0.3 — 15.1 Revenue — — — — 148.1 1.2 — 149.3 Costs and expenses: Property operating expenses — — — — 51.7 0.6 — 52.3 Sales and marketing — — — — 4.9 — — 4.9 General and administrative — — — — 15.8 — — 15.8 Depreciation and amortization — — — — 55.3 0.4 — 55.7 Transaction and acquisition integration costs — — — — 0.6 — — 0.6 Loss on disposal — — — — 0.2 — — 0.2 Total costs and expenses — — — — 128.5 1.0 — 129.5 Operating income — — — — 19.6 0.2 — 19.8 Interest expense — — 15.0 — — 0.6 (2.0 ) 13.6 Loss on extinguishment of debt — — 36.2 — — — — 36.2 (Loss) income before income taxes — — (51.2 ) — 19.6 (0.4 ) 2.0 (30.0 ) Income tax expense — — — — (0.4 ) — — (0.4 ) Equity (loss) earnings related to investment in subsidiaries (32.4 ) (0.3 ) 18.8 — (0.4 ) — 14.3 — Net (loss) income (32.4 ) (0.3 ) (32.4 ) — 18.8 (0.4 ) 16.3 (30.4 ) Noncontrolling interest in net (loss) income — — — — — — — — Net (loss) income attributed to common stockholders (32.4 ) (0.3 ) (32.4 ) — 18.8 (0.4 ) 16.3 (30.4 ) Other comprehensive loss — — — — — — — — Comprehensive (loss) income attributable to common stockholders $ (32.4 ) $ (0.3 ) $ (32.4 ) $ — $ 18.8 $ (0.4 ) $ 16.3 $ (30.4 ) IN MILLIONS Three Months Ended March 31, 2016 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Revenue: Base revenue and other $ — $ — $ — $ — $ 105.4 $ 1.1 $ — $ 106.5 Metered power reimbursements — — — — 11.0 0.3 — 11.3 Revenue — — — — 116.4 1.4 — 117.8 Costs and expenses: Property operating expenses — — — — 39.7 0.6 — 40.3 Sales and marketing — — — — 4.0 — — 4.0 General and administrative — — — — 14.0 — — 14.0 Depreciation and amortization — — — — 38.6 0.7 — 39.3 Transaction and acquisition integration costs — — — — 2.3 — — 2.3 Total costs and expenses — — — — 98.6 1.3 — 99.9 Operating income — — — — 17.8 0.1 — 17.9 Interest expense — — 11.7 — — 0.8 (0.4 ) 12.1 Income (loss) before income taxes — — (11.7 ) — 17.8 (0.7 ) 0.4 5.8 Income tax expense — — — — (0.2 ) — — (0.2 ) Equity earnings (loss) related to investment in subsidiaries 5.2 0.1 16.9 — (0.7 ) — (21.5 ) — Net income (loss) 5.2 0.1 5.2 — 16.9 (0.7 ) (21.1 ) 5.6 Net income (loss) attributed to common stockholders 5.2 0.1 5.2 — 16.9 (0.7 ) (21.1 ) 5.6 Other comprehensive loss — — — — — — — — Comprehensive income (loss) attributable to common stockholders $ 5.2 $ 0.1 $ 5.2 $ — $ 16.9 $ (0.7 ) $ (21.1 ) $ 5.6 Consolidating Statements of Cash Flows IN MILLIONS Three Months Ended March 31, 2017 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Cash flows from operating activities: Net (loss) income $ (32.4 ) $ (0.3 ) (32.4 ) $ — $ 18.8 $ (0.4 ) $ 16.3 $ (30.4 ) Equity (loss) earnings related to investment in subsidiaries 32.4 0.3 (18.8 ) — 0.4 — (14.3 ) — Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities: Depreciation and amortization — — — — 55.3 0.4 — 55.7 Non-cash interest expense and change in interest accrual — — (1.0 ) — — — — (1.0 ) Stock-based compensation expense — — — — 3.7 — — 3.7 Provision for bad debt — — — — — — — — Loss on extinguishment of debt — — 36.2 — — — — 36.2 Loss on disposal — — — — 0.2 — — 0.2 Change in operating assets and liabilities: Rent receivables and other assets — — — — (20.3 ) 0.3 — (20.0 ) Accounts payable and accrued expenses — — — — (5.9 ) 1.0 — (4.9 ) Deferred revenues — — — — 15.7 — — 15.7 Net cash provided by (used in) operating activities — — (16.0 ) — 67.9 1.3 2.0 55.2 Cash flows from investing activities: Capital expenditures - asset acquisitions, net of cash acquired — — — — (492.3 ) — — (492.3 ) Capital expenditures - other development — — — — (180.5 ) — (2.0 ) (182.5 ) Investment in subsidiaries (210.8 ) (2.1 ) (210.8 ) — — — 423.7 — Changes in restricted cash — — — — (0.6 ) — — (0.6 ) Return of investment 32.4 — — — — — (32.4 ) — Intercompany borrowings 6.2 — (401.5 ) — — — 395.3 — Net cash provided by (used in) investing activities (172.2 ) (2.1 ) (612.3 ) — (673.4 ) — 784.6 (675.4 ) Cash flows from financing activities: Issuance of common stock 211.0 — — — — — — 211.0 Dividends paid (32.4 ) — (32.4 ) — — — 32.4 (32.4 ) Intercompany borrowings — — (6.2 ) — 401.5 — (395.3 ) — Borrowings from credit facility — — 440.0 — — — — 440.0 Proceeds from issuance of debt — — 800.0 — — — — 800.0 Payments on credit facility — — (270.0 ) — — — — (270.0 ) Payments on senior notes — — (474.8 ) — — — — (474.8 ) Payments on capital leases and lease financing arrangements — — — — (2.1 ) (0.2 ) — (2.3 ) Tax payment upon exercise of equity awards (6.4 ) — — — — — — (6.4 ) Contributions/distributions from parent — 2.1 210.8 — 210.8 — (423.7 ) — Debt issuance costs — — (8.8 ) — — — — (8.8 ) Payment of debt extinguishment costs — — (30.3 ) — — — — (30.3 ) Net cash provided by (used in) financing activities 172.2 2.1 628.3 — 610.2 (0.2 ) (786.6 ) 626.0 Net increase in cash and cash equivalents — — — — 4.7 1.1 — 5.8 Cash and cash equivalents at beginning of period — — — — 13.4 1.2 — 14.6 Cash and cash equivalents at end of period $ — $ — $ — $ — $ 18.1 $ 2.3 $ — $ 20.4 IN MILLIONS Three Months Ended March 31, 2016 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Cash flows from operating activities: Net income (loss) $ 5.2 $ 0.1 $ 5.2 $ — $ 16.9 $ (0.7 ) $ (21.1 ) $ 5.6 Equity earnings (loss) related to investment in subsidiaries (5.2 ) (0.1 ) (16.9 ) — 0.7 — 21.5 — Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities: Depreciation and amortization — — — — 38.6 0.7 — 39.3 Non-cash interest expense and change in interest accrual — — 0.9 — — — — 0.9 Stock-based compensation expense — — — — 3.0 — — 3.0 Provision for bad debt — — — — 0.1 — — 0.1 Change in operating assets and liabilities: Rent receivables and other assets — — — — 6.0 0.2 — 6.2 Accounts payable and accrued expenses — — 7.1 — (7.1 ) — — — Deferred revenues — — — — (2.2 ) (0.1 ) — (2.3 ) Net cash provided by (used in) operating activities — — (3.7 ) — 56.0 0.1 0.4 52.8 Cash flows from investing activities: Capital expenditures - asset acquisitions, net of cash acquired — — — — (131.1 ) — — (131.1 ) Capital expenditures - other development — — — — (78.5 ) — — (78.5 ) Investment in subsidiaries (255.7 ) (2.6 ) (255.7 ) — — — 514.0 — Changes in restricted cash — — — — 0.8 — — 0.8 Return of investment 20.8 — — — — — (20.8 ) — Intercompany borrowings 13.5 — 27.1 — — — (40.6 ) — Net cash provided by (used in) investing activities (221.4 ) (2.6 ) (228.6 ) — (208.8 ) — 452.6 (208.8 ) Cash flows from financing activities: Issuance of common stock 256.0 — — — — — — 256.0 Dividends paid (20.8 ) — (22.8 ) — — — 20.8 (22.8 ) Intercompany borrowings — — (13.5 ) — (26.7 ) — 40.2 — Borrowings from credit facility — — 320.0 — — — — 320.0 Payments on credit facility — — (305.0 ) — — — — (305.0 ) Payments on capital leases and lease financing arrangements — — — — (2.0 ) (1.1 ) — (3.1 ) Tax payment upon exercise of equity awards (13.6 ) — — — — — — (13.6 ) Debt issuance costs — — (2.1 ) — — — — (2.1 ) Contributions/distributions from parent — 2.6 255.7 — 255.7 — (514.0 ) — Net cash provided by (used in) financing activities 221.6 2.6 232.3 — 227.0 (1.1 ) (453.0 ) 229.4 Net increase (decrease) in cash and cash equivalents 0.2 — — — 74.2 (1.0 ) — 73.4 Cash and cash equivalents at beginning of period — — — — 10.4 3.9 — 14.3 Cash and cash equivalents at end of period $ 0.2 $ — $ — $ — $ 84.6 $ 2.9 $ — $ 87.7

Subsequent Events

Subsequent Events	3 Months Ended
	Mar. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Subsequent to the end of the first quarter of 2017, CyrusOne exercised its option to purchase 48 acres of land in Quincy, Washington. The purchase positions the Company to offer what it believes to be one of the lowest cost data center solutions in the country and extends its geographic presence to the Pacific Northwest.

Significant Accounting Polici23

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	The accompanying financial statements as of March 31, 2017 and December 31, 2016 , and for the three months ended March 31, 2017 and March 31, 2016 , are prepared on a consolidated basis. In addition, the accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and should be read in conjunction with the financial statements and notes thereto included in our Annual Report on Form 10-K/A for the year ended December 31, 2016 , which was filed with the SEC on February 27, 2017. Certain information and footnote disclosures normally included in the condensed consolidated financial statements prepared in accordance with GAAP have been omitted from this report on Form 10-Q pursuant to the rules and regulations of the SEC. Results for the interim periods in this report are not necessarily indicative of future financial results and have not been audited by our independent registered public accounting firm. In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all adjustments necessary to present fairly our condensed consolidated financial statements as of March 31, 2017 , and for the three months ended March 31, 2017 and 2016 . These adjustments are of a normal recurring nature and consistent with the adjustments recorded to prepare the annual audited financial statements as of December 31, 2016 . All amounts reflected are in millions except share and per share data. Base revenue and other and metered power reimbursements for the three months ended March 31, 2016 have been presented separately to conform with the presentation for the three months ended March 31, 2017. There is no change to total revenue as a result of this change in presentation.
Use of Estimates	Use of Estimates —Preparation of the condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the condensed consolidated financial statements and accompanying notes. These estimates and assumptions are based on management’s knowledge of current events and actions that we may undertake in the future. Estimates are used in determining the fair value of leased real estate, including purchase price allocations for business combinations and asset acquisitions, the useful lives of real estate and other long-lived assets, future cash flows associated with goodwill and other long-lived asset impairment testing, deferred tax assets and liabilities and loss contingencies. Actual results may differ from these estimates and assumptions.
Investments in Real Estate	Investments in Real Estate —Investment in real estate consist of land, buildings, improvements and integral equipment utilized in our data center operations. Real estate acquired from third parties has been recorded at its acquisition cost. Additions and improvements which extend an asset’s useful life or increase its functionality are capitalized and depreciated over the asset’s remaining life. Maintenance and repairs are expensed as incurred. When we are involved in the construction of structural improvements to leased property, we are deemed the accounting owner of the leased real estate. In these instances, we bear substantially all the construction period risk, including managing or funding construction. As we have substantially all of the construction risks, we are deemed the “owner” of the asset under construction for accounting purposes during the construction period, and are therefore required to capitalize the construction costs on the accompanying consolidated balance sheets. At inception, the fair value of the building (excluding land) is recorded as an asset, and the construction and modification costs to the building that are not funded by us would be recorded as a liability. As construction progresses, the value of the asset and obligation increases by the fair value of the structural improvements. At completion of the construction, Sales-Leaseback Accounting under ASC 840-40-25 is also evaluated. Due to our continuing involvement with the lessor, Sales-Leaseback Accounting is precluded and the liability is not derecognized. When the asset is placed in service, depreciation commences, and the leased real estate is depreciated to the lesser of (i) its estimated fair value at the end of the term or (ii) the expected amount of the unamortized obligation at the end of the term. The associated obligation is presented as Lease financing arrangements in the accompanying consolidated balance sheets. When we are not deemed the accounting owner of leased real estate, we further evaluate the lease to determine whether the lease should be classified as a capital or operating lease. One of the following four characteristics must be present to classify a lease as a capital lease: (i) the lease transfers ownership of the property to the lessee by the end of the lease term, (ii) the lease contains a bargain purchase option, (iii) the lease term is equal to 75% or more of the estimated economic life of the leased property or (iv) the net present value of the lease payments is at least 90% of the fair value of the leased property. Construction in progress includes direct and indirect expenditures for the construction and expansion of our data centers and is stated at its acquisition cost. Independent contractors perform substantially all of the construction and expansion efforts of our data centers. Construction in progress includes costs incurred under construction contracts including project management services, engineering and schematic design services, design development, construction services and other construction-related fees and services. Interest, property taxes and certain labor costs are also capitalized during the construction of an asset. These costs are depreciated over the estimated useful life of the related assets. Depreciation is calculated using the straight-line method over the estimated useful life of the asset. Useful lives range from nine to thirty years for buildings, three to thirty years for building improvements, and two to twenty years for equipment. Leasehold improvements are amortized over the shorter of the asset’s useful life or the remaining lease term, including renewal options which are reasonably assured. Management reviews the carrying value of long-lived assets, including intangible assets with finite lives, when events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. Examples of such indicators may include a significant adverse change in the extent to which or manner in which the property is being used, an accumulation of costs significantly in excess of the amount originally expected for acquisition or development, or a history of operating or cash flow losses. When such indicators exist, we review an estimate of the undiscounted future cash flows expected to result from the use of an asset (or group of assets) and its eventual disposition and compare such amount to its carrying amount. We consider factors such as future operating income, leasing demand, competition and other factors. If our undiscounted net cash flows indicate that we are unable to recover the carrying value of the asset, an impairment loss is recognized. An impairment loss is measured as the amount by which the asset’s carrying value exceeds its estimated fair value.
Business Combinations and Asset Acquisitions	Business Combinations and Asset Acquisitions —The Company applies the purchase method for business combinations, where all tangible and identifiable intangible assets acquired and all liabilities assumed are recorded at fair value. Any excess purchase price is recorded as goodwill. Transaction costs associated with business combinations are expensed as incurred. Revenues and the results of operations of the acquired business are included in the accompanying condensed consolidated financial statements commencing on the date of acquisition. The Company applies a screen test to determine when a set is not a business. When substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. Purchase price paid for assets acquired is allocated between identified tangible and intangible assets acquired. Transaction costs associated with asset acquisitions are capitalized. Revenues and the results of operations of the acquired assets are included in the accompanying condensed consolidated financial statements commencing on the date of the asset acquisition.
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.
Restricted Cash	Restricted Cash —Restricted cash includes cash equivalents held to collateralize standby letters of credit and/or deposited in escrow to fund construction or pending potential acquisition transactions. In addition, we may have other cash that is not immediately available for use in current operations.
Rent and Other Receivables	Rent and Other Receivables —Receivables consist principally of trade receivables from customers and are generally unsecured and due within 30 to 120 days . Unbilled receivables arise from services rendered but not yet billed. Expected credit losses associated with trade receivables are recorded as an allowance for doubtful accounts. The allowance for doubtful accounts is estimated based upon historic patterns of credit losses for aged receivables as well as specific provisions for certain identifiable, potentially uncollectible balances. When internal collection efforts on accounts have been exhausted, the accounts are written-off and the associated allowance for doubtful accounts is reduced.
Deferred Leasing and Financing Costs	Deferred Leasing Costs —Deferred leasing costs are presented with Other assets in the accompanying consolidated balance sheets. Leasing commissions incurred at the commencement of a new lease are capitalized and amortized over the term of the customer lease. Amortization of deferred leasing costs is presented with Depreciation and amortization in the accompanying consolidated statements of operations. If a lease terminates prior to the expiration of the lease, the remaining unamortized cost is written off to amortization expense. As of March 31, 2017 and December 31, 2016 , deferred leasing costs were $24.7 million and $23.3 million , respectively. Deferred Financing Costs —Deferred financing costs include costs incurred in connection with issuance of debt, including our senior notes, term loans and revolving credit facilities. These costs include deferred financing costs associated with our revolving line of credit and are presented in the balance sheet as a direct reduction from the carrying amount of the debt liability. These financing costs are deferred and amortized to expense over the term of the instrument and are included as a component of Interest expense.
Revenue Recognition	Revenue Recognition —Colocation rentals are generally billed monthly in advance, and some contracts have escalating payments over the term of the contract. If rents escalate without the lessee gaining access to or control over additional leased space or power, and the lessee takes possession of, or controls the physical use of the property (including all contractually committed power) at the beginning of the lease term, the rental payments by the lessee are recognized as revenue on a straight-line basis over the term of the lease. If rents escalate because the lessee gains access to and control over additional leased space or power, revenue is recognized in proportion to the additional space or power in the periods that the lessee has control over the use of the additional space or power. The excess of revenue recognized over amounts contractually due is recognized in Other assets in the accompanying consolidated balance sheets. As of March 31, 2017 and December 31, 2016 , straight-line rent receivable was $77.3 million and $67.6 million , respectively. Revenue is recognized for services or products that are deemed separate units of accounting. When a customer makes an advance payment or they are contractually obligated to pay any amounts in advance, which is not deemed a separate unit of accounting, Deferred revenue liability is recorded. This revenue is recognized ratably over the expected term of the lease, unless the pattern of service suggests otherwise. As of March 31, 2017 and December 31, 2016, Deferred revenue was $93.3 million and $76.7 million , respectively. Some of our leases are structured on a full-service gross basis in which the customer pays a fixed amount for both colocation rent and power. Other leases provide that the customer will be billed for power based upon actual usage which is separately metered. In both cases, this revenue is presented as Revenue in the accompanying consolidated statements of operations. Power is generally billed one month in arrears, and an estimate of this revenue is accrued in the month that the associated costs are incurred. We generally are not entitled to reimbursements for real estate taxes, insurance or other operating expenses. In certain leases, we receive an administrative fee when we manage the meters for our customers. Certain customer leases require specified levels of service or performance. If we fail to meet these service levels, our customers may be eligible to receive credits on their contractual billings. These credits are recognized against revenue when an event occurs that gives rise to such credits. Customer credits were immaterial for each of the periods presented. A provision for doubtful accounts is recognized when the collection of contractual rent, straight-line rent or customer reimbursements are deemed to be uncollectible.
Depreciation and Amortization Expense	Depreciation and Amortization Expense —Depreciation expense is recognized over the estimated useful lives of real estate applying the straight-line method. The useful life of leased real estate and leasehold improvements is the lesser of the economic useful life of the asset or the term of the lease, including optional renewal periods if renewal of the lease is reasonably assured. The residual value of leased real estate is estimated as the lesser of (i) the expected fair value of the asset at the end of the lease term or (ii) the expected amount of the unamortized liability at the end of the lease term. Estimated useful lives are periodically reviewed. Depreciation expense was $48.9 million and $33.0 million for the three months ended March 31, 2017 and 2016, respectively. Amortization expense is recognized over the estimated useful lives of finite-lived intangibles. Finite-lived intangibles include trademarks, customer relationships, favorable leasehold interests, trade names and deferred leasing costs. As of March 31, 2017 , the estimated remaining weighted average useful life of trademarks and customer relationships was 9 and 12 years, respectively. In addition, we have a favorable leasehold interest related to a land lease that is being amortized over the lease term of 51 years. The trade name is being amortized over three years. Deferred leasing costs are amortized over 3 to 5 years.
Transaction and Acquisition Integration Costs	Transaction and Acquisition Integration Costs —Transaction costs represent incremental legal, accounting and professional fees incurred in connection with consummated and potential business combinations and integration costs post an asset acquisition. Transaction costs are expensed as incurred and do not include any recurring costs from our ongoing operations. Integration costs represent incremental costs to integrate a consummated acquisition.
Income Taxes	Income Taxes —The income tax provision consists of an amount for taxes currently payable and an amount for tax consequences deferred to future periods. CyrusOne Inc. has elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (the Code), commencing with our initial taxable year ending December 31, 2013. Provided we continue to meet the various qualification tests mandated under the Code, we are generally 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, our taxable income will be subject to federal income tax at regular corporate rates and any applicable alternative minimum tax, and we may not be able to qualify as a REIT for four subsequent taxable years. While CyrusOne Inc. and the operating partnership do not pay federal income taxes, we are still subject to foreign, state and local income taxes in the locations in which we conduct business. Our taxable REIT subsidiaries (each a TRS) are also subject to federal and state income taxes to the extent they earn taxable income. Deferred income taxes are recognized in certain entities. Deferred income taxes are provided for temporary differences in the basis between financial statement and income tax assets and liabilities. Deferred income taxes are recalculated annually at rates then in effect. Valuation allowances are recorded to reduce deferred tax assets to amounts that are more likely than not to be realized. The ultimate realization of the deferred tax assets depends upon our ability to generate future taxable income during the periods in which basis differences and other deductions become deductible and prior to the expiration of the net operating loss carryforwards. The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction as well as various foreign, state and local jurisdictions. The Company's previous tax filings are subject to normal reviews by regulatory agencies until the related statute of limitations expires. With a few exceptions, the Company is no longer subject to U.S. federal, state or local examinations for years prior to 2012, and we have no liabilities for uncertain tax positions as of March 31, 2017 .
Foreign Currency Translation and Transactions	Foreign Currency Translation and Transactions —The financial position of foreign subsidiaries is translated at the exchange rates in effect at the end of the period, while revenues and expenses are translated at average rates of exchange during the period. Gains or losses from translation of foreign operations where the local currency is the functional currency are included as components of other comprehensive (loss) income. Gains or losses from foreign currency transactions are included in determining net income.
Comprehensive Income (Loss)	Comprehensive Income (Loss) —Comprehensive income (loss) represents the change in net assets of a company from transactions and other events from nonowner sources. Comprehensive income (loss) comprises all components of net income (loss) and all components of other comprehensive income (loss).
Earnings Per Share	Earnings Per Share —Basic EPS includes only the weighted average number of common shares outstanding during the period. Diluted EPS includes the weighted average number of common shares and the dilutive effect of stock options, restricted stock and share unit awards outstanding during the period, when such instruments are dilutive. All outstanding unvested share-based payment awards that contain rights to nonforfeitable dividends are treated as participating in undistributed earnings with common shareholders. Awards of this nature are considered participating securities and the two-class method of computing basic and diluted EPS is applied.
Stock-Based Compensation	Stock-Based Compensation —Our board of directors adopted the 2012 Long-Term Incentive Plan (LTIP), which was amended and restated by our stockholders on May 2, 2016. The LTIP is administered by the compensation committee of the board of directors. Awards issuable under the LTIP include common stock, restricted stock, stock options and other incentive awards. See Note 9 for additional details relating to these awards. Share-based compensation expense is based on the estimated grant-date fair value. CyrusOne Inc. recognizes share-based compensation expense on a straight-line basis over the requisite service period for time-based awards and on a graded vesting basis for performance-based awards. We adopted ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting (Subtopic 718) in the fourth quarter of 2016 and elected to account for forfeitures as they occur. Prior to the adoption of this ASU, CyrusOne estimated forfeitures based on historical activity, expected employee turnover, and other qualitative factors which were adjusted for changes in estimates and award vesting. Expenses for an award are recognized by the time they become fully vested. CyrusOne Inc. uses the Black-Scholes-Merton option pricing model to calculate the fair value of stock options. This option valuation model requires the use of subjective assumptions, including the estimated fair value of the underlying common stock, the expected stock price volatility, and the expected term of the option. The estimated fair value of the underlying common stock is based on third-party valuations. Our volatility estimates are based on a peer group of companies. We estimate the expected term of the awards to be the weighted average mid-point between the vesting date and the end of the contractual term. For interim and annual periods, we use our year-to-date actual results, financial forecasts, and other available information to estimate the probability of the award vesting based on the performance metrics.
Fair Value Measurements	Fair Value Measurements —Fair value measurements are utilized in accounting for business combinations and testing of goodwill and other long-lived assets for impairment and disclosures. Fair value of financial and non-financial assets and liabilities is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. The three-tier hierarchy for inputs used in measuring fair value, which prioritizes the inputs used in the methodologies of measuring fair value for asset and liabilities, is as follows: Level 1—Observable inputs for identical instruments such as quoted market prices; Level 2—Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs); and Level 3—Unobservable inputs that reflect our determination of assumptions that market participants would use in pricing the asset or liability. These inputs are developed based on the best information available, including our own data.
Business Segments	Business Segments —Business segments are components of an enterprise for which separate financial information is available and regularly viewed by the chief operating decision maker to assess performance and allocate resources. Our chief operating decision maker, the Company's Chief Executive Officer, reviews our financial information on an aggregate basis. Furthermore, our data centers have similar economic characteristics and customers across all geographic locations, and our service offerings have similar production processes, deliver services in a similar manner and use the same types of facilities and similar technologies. As a result, we have concluded that we have one reportable business segment.
Recently Issued Accounting Standards	Recently Issued Accounting Standards — Accounting Standards Update (ASU) No. 2014-09 (ASU 2014-09), Revenue from Contracts with Customers (Topic 606) On May 28, 2014, the Financial Accounting Standards Board (FASB) issued ASU 2014-09, which supersedes the revenue recognition requirements in Topic 605, "Revenue Recognition" and most industry-specific guidance. The core principle of ASU 2014-09 is that a company will recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. On July 9, 2015, the FASB deferred the effective date of ASU 2014-09. The new revenue standard is effective for fiscal years, and interim periods within those years, beginning after December 15, 2017 (January 1, 2018 for CyrusOne) and allows either a full retrospective adoption to all periods presented or a modified retrospective adoption approach with the cumulative effect of initial application of the revised guidance recognized at the date of initial application. We are beginning to evaluate the adoption alternatives and the impact of ASU 2014-09 on our consolidated financial statements. Our initial evaluation is that revenue from base colocation services, which is a majority of our revenues, would not be impacted by the adoption of this standard and therefore, we are inclined to adopt the modified retrospective approach. Our initial conclusion may change when we complete our evaluation. ASU No. 2016-01 (ASU 2016-01), Financial Instruments-Overall (Subtopic 825-10) In January 2016, the FASB amended its standards related to the accounting of certain financial instruments. This amendment addresses certain aspects of recognition, measurement, presentation and disclosure. The new rules will become effective for annual and interim periods beginning after December 15, 2017. Early adoption is not permitted. We are in the process of evaluating the impact the amendment will have on the consolidated financial statements. ASU No. 2016-02 (ASU 2016-02), Leases (Topic 842) On February 25, 2016, the FASB issued ASU 2016-02. Lessees will need to recognize on their balance sheet a right-of-use asset and a lease liability for virtually all of their leases (other than leases that meet the definition of a short-term lease). The liability will be equal to the present value of lease payments. The asset will be based on the liability, subject to adjustment, such as for initial direct costs. For income statement purposes, the FASB retained a dual model, requiring leases to be classified as either operating or finance. Operating leases will result in straight-line expense (similar to current operating leases) while finance leases will result in a front-loaded expense pattern (similar to current capital leases). Classification will be based on criteria that are largely similar to those applied in current lease accounting. The standard is effective for CyrusOne beginning January 1, 2019. Early adoption is permitted. The new standard must be adopted using a modified retrospective transition, and provides for certain practical expedients. Transition will require application of the new guidance at the beginning of the earliest comparative period presented. We are beginning to evaluate the impact of ASU 2016-02 on our consolidated financial statements and timing of adoption. ASU No. 2016-10 (ASU 2016-10), Revenue from Contracts with Customers (Topic 606): Identifying Performance Obligations and Licensing (Topic 606) In April 2016, the FASB issued ASU 2016-10 in response to an issue communicated by the Transition Resource Group for Revenue Recognition (the TRG), a group which was formed by the FASB and the International Accounting Standards Board (IASB) (collectively, the Boards), whose objective is to inform the Boards of any issues that could arise with the implementation of a converged standard on recognition of revenue from contracts with customers. ASU 2016-10 does not change the core principal of the guidance in Topic 606, but adds clarification around identifying performance obligations and licensing. The amendments in this update affect the guidance in ASU 2014-09, Contracts with Customers (Topic 606), which is not yet effective, and therefore follow the same effective date and transition requirements. ASU 2014-09 is effective for CyrusOne on January 1, 2018 and allows either a full retrospective adoption to all periods presented or a modified retrospective adoption approach with the cumulative effect of initial application of the revised guidance recognized at the date of the initial application. We are currently evaluating the impact of ASU 2016-10 and ASU 2014-09 on the Company's consolidated financial statements. ASU No. 2016-12 (ASU 2016-12), Revenue from Contracts with Customers (Subtopic 606) In May 2016, the FASB issued guidance which amends certain aspects of the Board's new revenue standard, ASU 2014-09. The amendments include the collectibility of revenue, presentation of sales tax and other similar taxes collected from customers, contracts containing noncash considerations, and contract modifications and completed contracts at transition. The effective date and transition provisions are aligned with the requirements of ASU 2014-09 (as described above). We are currently evaluating the full impact of the new standard. ASU No. 2016-13 (ASU 2016-13), Measurement of Credit Losses on Financial Instruments (Subtopic 326) In June 2016, the FASB issued guidance which requires a financial asset measured at amortized cost basis to be presented at the net amount expected to be collected. The amendments affect entities holding financial assets and net investment in leases that are not accounted for at fair value through net income. The amendments affect loans, debt securities, trade receivables, net investments in leases, off-balance-sheet credit exposures, reinsurance receivables, and any other financial assets not excluded from the scope that have the contractual right to receive cash. The guidance is effective for annual periods beginning after December 15, 2019. Early adoption is permitted. We are currently evaluating the full impact of the new standard. ASU No. 2016-18 (ASU 2016-18), Restricted Cash (Subtopic 230) In November 2016, the FASB issued guidance which addresses the diversity in the classification and presentation of changes in restricted cash on the statement of cash flows. The amendment requires that a statement of cash flows explain the change during the period in the total of cash. The guidance is effective for annual periods beginning after December 15, 2017. Early adoption is permitted. We are currently evaluating the full impact of the new standard. ASU No. 2017-01 (ASU 2017-01), Business Combinations (Topic 805) In January 2017, the FASB issued guidance which clarifies the definition of a business with the objective of adding guidance to assist entities with evaluating whether transactions should be accounted for as acquisitions (or disposals) of assets or businesses. The definition of a business affects many areas of accounting including acquisitions, disposals, goodwill and consolidation. Under this new guidance, the Company expects most acquisitions of investment property will meet the definition of an asset and, thus, be accounted for as asset acquisitions. Consistent with existing guidance, transaction costs associated with asset acquisitions are capitalized while transaction costs associated with business combinations are expensed as incurred. The guidance is effective for annual periods beginning after December 15, 2017. Early adoption is permitted. We adopted this standard on January 1, 2017, and applied the new guidance for the acquisition of the Sentinel Properties. ASU No. 2017-04 (ASU 2017-04), Goodwill and Other (Topic 350) In January 2017, the FASB issued ASU 2017-04 in order to simplify the test for goodwill impairment by eliminating Step 2, which measures a goodwill impairment loss by comparing the implied fair value of a reporting unit's goodwill with the carrying amount of that goodwill. Under the amendments in this Update, an entity should perform its annual goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit's fair value. However, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. The guidance is effective for CyrusOne beginning on January 1, 2020 and early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We adopted this standard on January 1, 2017. The adoption of this standard will not have a material impact on our consolidated financial statements. ASU No. 2017-05 (ASU 2017-05), Other Income—Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20)—Clarifying the Scope of Asset Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets In February 2017, the FASB issued ASU 2017-05, Other Income – Gains and Losses from the Derecognition of Nonfinancial Assets (Topic 610-20), which requires that all entities account for the derecognition of a business in accordance with ASC 810, Consolidations, including instances in which the business is considered in substance real estate. The ASU is effective for annual periods, and interim periods therein, beginning after December 15, 2017. Early application is permitted. We are currently evaluating the full impact of the new standard.

Asset Acquisitions (Tables)

Asset Acquisitions (Tables)	3 Months Ended
	Mar. 31, 2017
Business Combinations [Abstract]
Schedule of Estimated Fair Values of All Assets Acquired	The following table summarizes the estimated fair values of all assets acquired at the date of acquisition: IN MILLIONS Net investment in real estate $ 420.3 Cash and cash equivalents 3.2 Intangible assets: Above/Below market leases 2.3 In-place leases 75.8 Other assets 2.4 Payables (5.4 ) Deferred revenue (0.9 ) Capital lease obligation (2.2 ) Net assets acquired attributable to CyrusOne Inc. 495.5 Cash acquired (3.2 ) Net cash paid at acquisition $ 492.3

Long-Term Debt, Capital Lease25

Long-Term Debt, Capital Lease Obligations and Lease Financing Arrangements (Tables)	3 Months Ended
	Mar. 31, 2017
Debt Disclosure [Abstract]
Long-Term Debt and Capital Lease Obligations	Long-term debt, Capital lease obligations and Lease financing arrangements presented in the accompanying condensed consolidated financial statements consist of the following: IN MILLIONS As of March 31, 2017 December 31, 2016 Credit facilities: Revolving Credit Facility $ 405.0 $ 235.0 Term Loans 550.0 550.0 2024 Notes 500.0 — 2027 Notes 300.0 — 2022 Notes, including bond premium — 477.3 Deferred financing costs (23.2 ) (22.2 ) Long-term debt 1,731.8 1,240.1 Capital lease obligations 12.4 10.8 Lease financing arrangements 134.5 135.7 Total $ 1,878.7 $ 1,386.6

Fair Value of Financial Instr26

Fair Value of Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2017
Fair Value Disclosures [Abstract]
Carrying Value and Fair Value of Other Financial Instruments	The carrying value and fair value of other financial instruments are as follows: IN MILLIONS As of March 31, 2017 December 31, 2016 Carrying Value Fair Value Carrying Value Fair Value 2024 Notes $ 500.0 $ 511.3 $ — $ — 2027 Notes 300.0 303.8 — — 2022 Notes — — 477.3 502.1 Revolving Credit Facility and Term Loans 955.0 955.0 785.0 785.0

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	3 Months Ended
	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Compensation Expense	Stock-based compensation expense was as follows: IN MILLIONS Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Founders $ — $ 0.3 2013 Grants — 0.1 2014 Grants 0.1 0.3 2015 Grants 0.8 1.1 2016 Grants 1.9 1.2 2017 Grants 0.9 — Total $ 3.7 $ 3.0

(Loss) Income per Share (Tables

(Loss) Income per Share (Tables)	3 Months Ended
	Mar. 31, 2017
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net (Loss) Income per Share	The following table reflects the computation of basic and diluted net (loss) income per share for the three months ended March 31, 2017 and 2016 : IN MILLIONS, except per share amounts Three Months Ended March 31, 2017 Three Months Ended March 31, 2016 Basic Diluted Basic Diluted Numerator: Net (loss) income attributed to common stockholders $ (30.4 ) $ (30.4 ) $ 5.6 $ 5.6 Less: Restricted stock dividends (0.2 ) (0.2 ) (0.2 ) (0.2 ) Net (loss) income available to stockholders $ (30.6 ) $ (30.6 ) $ 5.4 $ 5.4 Denominator: Weighted average common outstanding-basic 84.0 84.0 72.1 72.1 Performance-based restricted stock and units — 0.6 Convertible securities — 0.1 Weighted average shares outstanding-diluted 84.0 72.8 EPS: Net (loss) income per share-basic $ (0.36 ) $ 0.07 Effect of dilutive shares: Net (loss) income per share-diluted $ (0.36 ) $ 0.07

Guarantors (Tables)

Guarantors (Tables)	3 Months Ended
	Mar. 31, 2017
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Consolidating Balance Sheets	Consolidating Balance Sheets IN MILLIONS As of March 31, 2017 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Land $ — $ — $ — $ — $ 156.9 $ — $ — $ 156.9 Buildings and improvements — — — — 1,234.8 34.8 1.3 1,270.9 Equipment — — — — 1,431.6 1.0 5.4 1,438.0 Construction in progress — — — — 369.4 — 2.3 371.7 Subtotal — — — — 3,192.7 35.8 9.0 3,237.5 Accumulated depreciation — — — — (618.1 ) (7.8 ) — (625.9 ) Net investment in real estate — — — — 2,574.6 28.0 9.0 2,611.6 Cash and cash equivalents — — — — 18.1 2.3 — 20.4 Investment in subsidiaries 1,316.1 13.2 1,609.3 — 1.6 — (2,940.2 ) — Restricted cash — — — — 0.6 — — 0.6 Rent and other receivables, net — — — — 88.0 1.4 — 89.4 Intercompany receivable 16.2 — 1,459.1 — — 0.5 (1,475.8 ) — Goodwill — — — — 455.1 — — 455.1 Intangible assets, net — — — — 223.1 — — 223.1 Other assets — — — — 141.1 2.5 — 143.6 Total assets $ 1,332.3 $ 13.2 $ 3,068.4 $ — $ 3,502.2 $ 34.7 $ (4,407.0 ) $ 3,543.8 Accounts payable and accrued expenses $ 37.7 $ — $ 4.3 $ — $ 224.5 $ 1.7 $ — $ 268.2 Deferred revenue — — — — 92.6 0.7 — 93.3 Intercompany payable — — 16.2 — 1,459.6 — (1,475.8 ) — Capital lease obligations — — — — 7.2 5.2 — 12.4 Long-term debt, net — — 1,731.8 — — — — 1,731.8 Lease financing arrangements — — — — 109.0 25.5 — 134.5 Total liabilities 37.7 — 1,752.3 — 1,892.9 33.1 (1,475.8 ) 2,240.2 Total stockholders' equity 1,294.6 13.2 1,316.1 — 1,609.3 1.6 (2,931.2 ) 1,303.6 Total liabilities and equity $ 1,332.3 $ 13.2 $ 3,068.4 $ — $ 3,502.2 $ 34.7 $ (4,407.0 ) $ 3,543.8 IN MILLIONS As of December 31, 2016 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Land $ — $ — $ — $ — $ 142.7 $ — $ — $ 142.7 Buildings and improvements — — — — 973.6 34.1 1.2 1,008.9 Equipment — — — — 1,036.8 1.0 5.1 1,042.9 Construction in progress — — — — 406.4 — 0.7 407.1 Subtotal — — — — 2,559.5 35.1 7.0 2,601.6 Accumulated depreciation — — — — (571.3 ) (7.2 ) — (578.5 ) Net investment in real estate — — — — 1,988.2 27.9 7.0 2,023.1 Cash and cash equivalents — — — — 13.4 1.2 — 14.6 Investment in subsidiaries 1,170.3 11.7 1,376.1 — 2.0 — (2,560.1 ) — Rent and other receivables, net — — — — 81.8 1.5 — 83.3 Intercompany receivable 18.6 — 1,057.7 — — 0.5 (1,076.8 ) — Goodwill — — — — 455.1 — — 455.1 Intangible assets, net — — — — 150.2 — — 150.2 Other assets — — — — 123.4 2.7 — 126.1 Total assets $ 1,188.9 $ 11.7 $ 2,433.8 $ — $ 2,814.1 $ 33.8 $ (3,629.9 ) $ 2,852.4 Accounts payable and accrued expenses $ 33.9 $ — $ 4.8 $ — $ 187.7 $ 0.7 $ — $ 227.1 Deferred revenue — — — — 76.0 0.7 — 76.7 Intercompany payable — — 18.6 — 1,058.2 — (1,076.8 ) — Capital lease obligations — — — — 5.6 5.2 — 10.8 Long-term debt, net — — 1,240.1 — — — — 1,240.1 Lease financing arrangements — — — — 110.5 25.2 — 135.7 Total liabilities 33.9 — 1,263.5 — 1,438.0 31.8 (1,076.8 ) 1,690.4 Total stockholders' equity 1,155.0 11.7 1,170.3 — 1,376.1 2.0 (2,553.1 ) 1,162.0 Total liabilities and equity $ 1,188.9 $ 11.7 $ 2,433.8 $ — $ 2,814.1 $ 33.8 $ (3,629.9 ) $ 2,852.4
Consolidating Statements of Operations and Comprehensive Income (Loss)	Consolidating Statements of Operations and Comprehensive Income (Loss) IN MILLIONS Three Months Ended March 31, 2017 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/ Consolidations Total Revenue: Base revenue and other $ — $ — $ — $ — $ 133.3 $ 0.9 $ — $ 134.2 Metered power reimbursements — — — — 14.8 0.3 — 15.1 Revenue — — — — 148.1 1.2 — 149.3 Costs and expenses: Property operating expenses — — — — 51.7 0.6 — 52.3 Sales and marketing — — — — 4.9 — — 4.9 General and administrative — — — — 15.8 — — 15.8 Depreciation and amortization — — — — 55.3 0.4 — 55.7 Transaction and acquisition integration costs — — — — 0.6 — — 0.6 Loss on disposal — — — — 0.2 — — 0.2 Total costs and expenses — — — — 128.5 1.0 — 129.5 Operating income — — — — 19.6 0.2 — 19.8 Interest expense — — 15.0 — — 0.6 (2.0 ) 13.6 Loss on extinguishment of debt — — 36.2 — — — — 36.2 (Loss) income before income taxes — — (51.2 ) — 19.6 (0.4 ) 2.0 (30.0 ) Income tax expense — — — — (0.4 ) — — (0.4 ) Equity (loss) earnings related to investment in subsidiaries (32.4 ) (0.3 ) 18.8 — (0.4 ) — 14.3 — Net (loss) income (32.4 ) (0.3 ) (32.4 ) — 18.8 (0.4 ) 16.3 (30.4 ) Noncontrolling interest in net (loss) income — — — — — — — — Net (loss) income attributed to common stockholders (32.4 ) (0.3 ) (32.4 ) — 18.8 (0.4 ) 16.3 (30.4 ) Other comprehensive loss — — — — — — — — Comprehensive (loss) income attributable to common stockholders $ (32.4 ) $ (0.3 ) $ (32.4 ) $ — $ 18.8 $ (0.4 ) $ 16.3 $ (30.4 ) IN MILLIONS Three Months Ended March 31, 2016 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Revenue: Base revenue and other $ — $ — $ — $ — $ 105.4 $ 1.1 $ — $ 106.5 Metered power reimbursements — — — — 11.0 0.3 — 11.3 Revenue — — — — 116.4 1.4 — 117.8 Costs and expenses: Property operating expenses — — — — 39.7 0.6 — 40.3 Sales and marketing — — — — 4.0 — — 4.0 General and administrative — — — — 14.0 — — 14.0 Depreciation and amortization — — — — 38.6 0.7 — 39.3 Transaction and acquisition integration costs — — — — 2.3 — — 2.3 Total costs and expenses — — — — 98.6 1.3 — 99.9 Operating income — — — — 17.8 0.1 — 17.9 Interest expense — — 11.7 — — 0.8 (0.4 ) 12.1 Income (loss) before income taxes — — (11.7 ) — 17.8 (0.7 ) 0.4 5.8 Income tax expense — — — — (0.2 ) — — (0.2 ) Equity earnings (loss) related to investment in subsidiaries 5.2 0.1 16.9 — (0.7 ) — (21.5 ) — Net income (loss) 5.2 0.1 5.2 — 16.9 (0.7 ) (21.1 ) 5.6 Net income (loss) attributed to common stockholders 5.2 0.1 5.2 — 16.9 (0.7 ) (21.1 ) 5.6 Other comprehensive loss — — — — — — — — Comprehensive income (loss) attributable to common stockholders $ 5.2 $ 0.1 $ 5.2 $ — $ 16.9 $ (0.7 ) $ (21.1 ) $ 5.6
Consolidating Statements of Cash Flows	Consolidating Statements of Cash Flows IN MILLIONS Three Months Ended March 31, 2017 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Cash flows from operating activities: Net (loss) income $ (32.4 ) $ (0.3 ) (32.4 ) $ — $ 18.8 $ (0.4 ) $ 16.3 $ (30.4 ) Equity (loss) earnings related to investment in subsidiaries 32.4 0.3 (18.8 ) — 0.4 — (14.3 ) — Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities: Depreciation and amortization — — — — 55.3 0.4 — 55.7 Non-cash interest expense and change in interest accrual — — (1.0 ) — — — — (1.0 ) Stock-based compensation expense — — — — 3.7 — — 3.7 Provision for bad debt — — — — — — — — Loss on extinguishment of debt — — 36.2 — — — — 36.2 Loss on disposal — — — — 0.2 — — 0.2 Change in operating assets and liabilities: Rent receivables and other assets — — — — (20.3 ) 0.3 — (20.0 ) Accounts payable and accrued expenses — — — — (5.9 ) 1.0 — (4.9 ) Deferred revenues — — — — 15.7 — — 15.7 Net cash provided by (used in) operating activities — — (16.0 ) — 67.9 1.3 2.0 55.2 Cash flows from investing activities: Capital expenditures - asset acquisitions, net of cash acquired — — — — (492.3 ) — — (492.3 ) Capital expenditures - other development — — — — (180.5 ) — (2.0 ) (182.5 ) Investment in subsidiaries (210.8 ) (2.1 ) (210.8 ) — — — 423.7 — Changes in restricted cash — — — — (0.6 ) — — (0.6 ) Return of investment 32.4 — — — — — (32.4 ) — Intercompany borrowings 6.2 — (401.5 ) — — — 395.3 — Net cash provided by (used in) investing activities (172.2 ) (2.1 ) (612.3 ) — (673.4 ) — 784.6 (675.4 ) Cash flows from financing activities: Issuance of common stock 211.0 — — — — — — 211.0 Dividends paid (32.4 ) — (32.4 ) — — — 32.4 (32.4 ) Intercompany borrowings — — (6.2 ) — 401.5 — (395.3 ) — Borrowings from credit facility — — 440.0 — — — — 440.0 Proceeds from issuance of debt — — 800.0 — — — — 800.0 Payments on credit facility — — (270.0 ) — — — — (270.0 ) Payments on senior notes — — (474.8 ) — — — — (474.8 ) Payments on capital leases and lease financing arrangements — — — — (2.1 ) (0.2 ) — (2.3 ) Tax payment upon exercise of equity awards (6.4 ) — — — — — — (6.4 ) Contributions/distributions from parent — 2.1 210.8 — 210.8 — (423.7 ) — Debt issuance costs — — (8.8 ) — — — — (8.8 ) Payment of debt extinguishment costs — — (30.3 ) — — — — (30.3 ) Net cash provided by (used in) financing activities 172.2 2.1 628.3 — 610.2 (0.2 ) (786.6 ) 626.0 Net increase in cash and cash equivalents — — — — 4.7 1.1 — 5.8 Cash and cash equivalents at beginning of period — — — — 13.4 1.2 — 14.6 Cash and cash equivalents at end of period $ — $ — $ — $ — $ 18.1 $ 2.3 $ — $ 20.4 IN MILLIONS Three Months Ended March 31, 2016 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Cash flows from operating activities: Net income (loss) $ 5.2 $ 0.1 $ 5.2 $ — $ 16.9 $ (0.7 ) $ (21.1 ) $ 5.6 Equity earnings (loss) related to investment in subsidiaries (5.2 ) (0.1 ) (16.9 ) — 0.7 — 21.5 — Adjustments to reconcile net income (loss) to net cash (used in) provided by operating activities: Depreciation and amortization — — — — 38.6 0.7 — 39.3 Non-cash interest expense and change in interest accrual — — 0.9 — — — — 0.9 Stock-based compensation expense — — — — 3.0 — — 3.0 Provision for bad debt — — — — 0.1 — — 0.1 Change in operating assets and liabilities: Rent receivables and other assets — — — — 6.0 0.2 — 6.2 Accounts payable and accrued expenses — — 7.1 — (7.1 ) — — — Deferred revenues — — — — (2.2 ) (0.1 ) — (2.3 ) Net cash provided by (used in) operating activities — — (3.7 ) — 56.0 0.1 0.4 52.8 Cash flows from investing activities: Capital expenditures - asset acquisitions, net of cash acquired — — — — (131.1 ) — — (131.1 ) Capital expenditures - other development — — — — (78.5 ) — — (78.5 ) Investment in subsidiaries (255.7 ) (2.6 ) (255.7 ) — — — 514.0 — Changes in restricted cash — — — — 0.8 — — 0.8 Return of investment 20.8 — — — — — (20.8 ) — Intercompany borrowings 13.5 — 27.1 — — — (40.6 ) — Net cash provided by (used in) investing activities (221.4 ) (2.6 ) (228.6 ) — (208.8 ) — 452.6 (208.8 ) Cash flows from financing activities: Issuance of common stock 256.0 — — — — — — 256.0 Dividends paid (20.8 ) — (22.8 ) — — — 20.8 (22.8 ) Intercompany borrowings — — (13.5 ) — (26.7 ) — 40.2 — Borrowings from credit facility — — 320.0 — — — — 320.0 Payments on credit facility — — (305.0 ) — — — — (305.0 ) Payments on capital leases and lease financing arrangements — — — — (2.0 ) (1.1 ) — (3.1 ) Tax payment upon exercise of equity awards (13.6 ) — — — — — — (13.6 ) Debt issuance costs — — (2.1 ) — — — — (2.1 ) Contributions/distributions from parent — 2.6 255.7 — 255.7 — (514.0 ) — Net cash provided by (used in) financing activities 221.6 2.6 232.3 — 227.0 (1.1 ) (453.0 ) 229.4 Net increase (decrease) in cash and cash equivalents 0.2 — — — 74.2 (1.0 ) — 73.4 Cash and cash equivalents at beginning of period — — — — 10.4 3.9 — 14.3 Cash and cash equivalents at end of period $ 0.2 $ — $ — $ — $ 84.6 $ 2.9 $ — $ 87.7

Description of Business - Narra

Description of Business - Narrative (Details)	3 Months Ended
	Mar. 31, 2017recovery_centerdata_center
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of data operating centers | data_center	39
Number of recovery centers | recovery_center	2

Recent Developments - Narrative

Recent Developments - Narrative (Details) shares in Millions	Mar. 17, 2017USD ($)	Feb. 28, 2017USD ($)data_center	Feb. 27, 2017USD ($)shares	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)	Nov. 20, 2012
Business Formation [Line Items]
Proceeds from public stock offerings				$ 211,000,000	$ 256,000,000
Debt proceeds, net of underwriting costs	$ 791,200,000
Debt underwriting costs	8,800,000
Debt other costs	1,500,000
Sentinel Properties
Business Formation [Line Items]
Number of data center facilities acquired | data_center		2
Consideration for acquisition		$ 492,300,000
Transaction related costs		$ 1,500,000
Senior notes | 6.375% senior notes due 2022
Business Formation [Line Items]
Repurchased face amount				474,800,000
Cyrus One LP And Cyrus One Finance Corp | Senior notes | 5.000% senior notes due 2024
Business Formation [Line Items]
Debt principal amount	$ 500,000,000			500,000,000
Stated interest rate	5.00%
Cyrus One LP And Cyrus One Finance Corp | Senior notes | 5.375% senior notes due 2027
Business Formation [Line Items]
Debt principal amount	$ 300,000,000			300,000,000
Stated interest rate	5.375%
Cyrus One LP And Cyrus One Finance Corp | Senior notes | 6.375% senior notes due 2022
Business Formation [Line Items]
Stated interest rate						6.375%
Public stock offering | Goldman, Sachs & Co.
Business Formation [Line Items]
Issuance of common stock (in shares) | shares			4.4
Proceeds from public stock offerings			$ 210,800,000
Employee stock purchase plans
Business Formation [Line Items]
Proceeds from public stock offerings				$ 200,000

Significant Accounting Polici32

Significant Accounting Policies - Narrative (Details)	3 Months Ended		12 Months Ended
	Mar. 31, 2017USD ($)segment	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)
Summary Of Significant Accounting Policies [Line Items]
Percentage of lease term	75.00%
Percentage of lease payment	90.00%
Asset impairments	$ 0	$ 0
Deferred leasing costs	24,700,000		$ 23,300,000
Straight-line rent receivable	77,300,000		67,600,000
Deferred revenue	93,300,000		$ 76,700,000
Depreciation expense	48,900,000	33,000,000
Amortization expense	6,800,000	$ 6,300,000
Unrecognized tax benefits	$ 0
Number of segments | segment	1
Leasehold improvement
Summary Of Significant Accounting Policies [Line Items]
Weighted-average remaining life (in years)	51 years
Trade name
Summary Of Significant Accounting Policies [Line Items]
Weighted-average remaining life (in years)	3 years
Minimum
Summary Of Significant Accounting Policies [Line Items]
Receivables due term	30 days
Minimum | Customer relationships and trademarks
Summary Of Significant Accounting Policies [Line Items]
Weighted-average remaining life (in years)	9 years
Minimum | Deferred leasing costs
Summary Of Significant Accounting Policies [Line Items]
Weighted-average remaining life (in years)	3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Receivables due term	120 days
Maximum | Customer relationships and trademarks
Summary Of Significant Accounting Policies [Line Items]
Weighted-average remaining life (in years)	12 years
Maximum | Deferred leasing costs
Summary Of Significant Accounting Policies [Line Items]
Weighted-average remaining life (in years)	5 years
Buildings | Minimum
Summary Of Significant Accounting Policies [Line Items]
Useful life	9 years
Buildings | Maximum
Summary Of Significant Accounting Policies [Line Items]
Useful life	30 years
Building Improvements | Minimum
Summary Of Significant Accounting Policies [Line Items]
Useful life	3 years
Building Improvements | Maximum
Summary Of Significant Accounting Policies [Line Items]
Useful life	30 years
Equipment | Minimum
Summary Of Significant Accounting Policies [Line Items]
Useful life	2 years
Equipment | Maximum
Summary Of Significant Accounting Policies [Line Items]
Useful life	20 years
Customer Concentration Risk | One customer | Revenue
Summary Of Significant Accounting Policies [Line Items]
Concentration risk, percentage	17.00%

Asset Acquisitions - Narrative

Asset Acquisitions - Narrative (Details) ft² in Thousands, $ in Millions	Feb. 28, 2017USD ($)ft²data_centerMW	Feb. 27, 2017USD ($)	Apr. 01, 2016	Mar. 31, 2016USD ($)ft²	Mar. 31, 2017USD ($)	Mar. 31, 2016USD ($)ft²	Mar. 31, 2016a
Business Acquisition [Line Items]
Issuance of common stock					$ 211	$ 256
CME Group's Data Center
Business Acquisition [Line Items]
Area acquired (in sqft or acre)				428		428	15
Payments for properties				$ 131.1
Lease term of favorable leasehold interest which being amortized			15 years
Public stock offering | Goldman, Sachs & Co.
Business Acquisition [Line Items]
Issuance of common stock		$ 210.8
Sentinel Properties
Business Acquisition [Line Items]
Number of data center facilities acquired | data_center	2
Consideration for acquisition	$ 492.3
Transaction related costs	$ 1.5
Sentinel Properties | Data center
Business Acquisition [Line Items]
Area acquired (in sqft or acre) | ft²	160
Amount of power capacity acquired | MW	21
Amount of leased power capacity	85.00%

Asset Acquisitions - Schedule o

Asset Acquisitions - Schedule of estimated fair values of all assets acquired (Details) - Sentinel Properties $ in Millions	Feb. 28, 2017USD ($)
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Net investment in real estate	$ 420.3
Cash and cash equivalents	3.2
Intangible assets:
Other assets	2.4
Payables	(5.4)
Deferred revenue	(0.9)
Capital lease obligation	(2.2)
Net assets acquired attributable to CyrusOne Inc.	495.5
Cash acquired	(3.2)
Net cash paid at acquisition	492.3
Above/Below market leases
Intangible assets:
Intangible assets	2.3
In-place leases
Intangible assets:
Intangible assets	$ 75.8

Long-Term Debt, Capital Lease35

Long-Term Debt, Capital Lease Obligations and Lease Financing Arrangements - Long-Term Debt and Capital Lease Obligations (Details) - USD ($) $ in Millions	Mar. 31, 2017	Mar. 30, 2017	Dec. 31, 2016	Mar. 17, 2016
Debt Instrument [Line Items]
Long-term debt, net	$ 1,731.8		$ 1,240.1
Deferred financing costs	(23.2)		(22.2)
Capital lease obligations	12.4		10.8
Lease financing arrangements	134.5		135.7
Total	1,878.7		1,386.6
Senior Notes | 2024 Notes
Debt Instrument [Line Items]
Long-term debt, net	500		0
Senior Notes | 2027 Notes
Debt Instrument [Line Items]
Long-term debt, net	300		0
Senior Notes | 2022 Notes, including bond premium
Debt Instrument [Line Items]
Long-term debt, net	0	$ 474.8	477.3
Revolving Credit Facility
Debt Instrument [Line Items]
Revolving Credit Facility	405		235
Revolving Credit Facility | Term Loan
Debt Instrument [Line Items]
Revolving Credit Facility	$ 550		$ 550
Deferred financing costs				$ (2.1)

Long-Term Debt, Capital Lease36

Long-Term Debt, Capital Lease Obligations and Lease Financing Arrangements - Narrative (Details)	Mar. 17, 2017USD ($)	Mar. 17, 2016USD ($)	Mar. 31, 2017USD ($)	Mar. 31, 2017USD ($)data_center	Mar. 31, 2016USD ($)	Mar. 30, 2017USD ($)	Dec. 31, 2016USD ($)	Nov. 21, 2016USD ($)	Dec. 31, 2015USD ($)	Nov. 20, 2012USD ($)
Debt Instrument [Line Items]
Deferred financing costs			$ 23,200,000	$ 23,200,000			$ 22,200,000
Letters of credit			8,500,000	8,500,000
Total liquidity			606,900,000	606,900,000
Cash equivalents			20,400,000	20,400,000	$ 87,700,000		14,600,000		$ 14,300,000
Debt proceeds, net of underwriting costs	$ 791,200,000
Debt financing and underwriting costs	8,800,000
Debt other costs	1,500,000
Long-term debt, net			$ 1,731,800,000	$ 1,731,800,000			1,240,100,000
Total unencumbered assets				150.00%
Amortization of deferred financing costs				$ 1,000,000	900,000
Number of data center facilities under capital leases | data_center				8
Interest expense on capital lease obligations				$ 2,300,000	2,400,000
Term Loan
Debt Instrument [Line Items]
Effective interest rate			2.48%	2.48%
Term Loan | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.50%
Term Loan | Credit Agreement
Debt Instrument [Line Items]
Credit agreement amount		$ 300,000,000
Term Loan | First Amended and Restated Credit Agreement
Debt Instrument [Line Items]
Optional additional borrowing capacity		$ 250,000,000
Senior Notes | 5.000% senior notes due 2024 and 5.375% senior notes due 2027 | Cyrus One LP And Cyrus One Finance Corp
Debt Instrument [Line Items]
Debt financing and underwriting costs	$ 10,300,000
Senior Notes | 5.000% senior notes due 2024
Debt Instrument [Line Items]
Long-term debt, net			$ 500,000,000	$ 500,000,000			0
Senior Notes | 5.000% senior notes due 2024 | Redemption period one
Debt Instrument [Line Items]
Debt redemption percentage	100.00%
Senior Notes | 5.000% senior notes due 2024 | Redemption period two
Debt Instrument [Line Items]
Debt redemption percentage	102.50%
Senior Notes | 5.000% senior notes due 2024 | Redemption period three
Debt Instrument [Line Items]
Debt redemption percentage	101.25%
Senior Notes | 5.000% senior notes due 2024 | Redemption period four
Debt Instrument [Line Items]
Debt redemption percentage	100.00%
Senior Notes | 5.000% senior notes due 2024 | Redemption period six
Debt Instrument [Line Items]
Debt redemption percentage	40.00%
Debt redemption, percentage of certain equity offerings	105.00%
Debt redemption, percentage to remain outstanding	55.00%
Debt redemption period after equity offering closing	90 days
Senior Notes | 5.000% senior notes due 2024 | Cyrus One LP And Cyrus One Finance Corp
Debt Instrument [Line Items]
Stated interest rate	5.00%
Debt principal amount	$ 500,000,000		500,000,000	500,000,000
Senior Notes | 5.375% senior notes due 2027
Debt Instrument [Line Items]
Long-term debt, net			300,000,000	300,000,000			0
Senior Notes | 5.375% senior notes due 2027 | Redemption period one
Debt Instrument [Line Items]
Debt redemption percentage	100.00%
Senior Notes | 5.375% senior notes due 2027 | Redemption period two
Debt Instrument [Line Items]
Debt redemption percentage	102.688%
Senior Notes | 5.375% senior notes due 2027 | Redemption period three
Debt Instrument [Line Items]
Debt redemption percentage	101.792%
Senior Notes | 5.375% senior notes due 2027 | Redemption period four
Debt Instrument [Line Items]
Debt redemption percentage	100.896%
Senior Notes | 5.375% senior notes due 2027 | Redemption period five
Debt Instrument [Line Items]
Debt redemption percentage	100.00%
Senior Notes | 5.375% senior notes due 2027 | Redemption period six
Debt Instrument [Line Items]
Debt redemption percentage	40.00%
Debt redemption, percentage of certain equity offerings	105.375%
Debt redemption, percentage to remain outstanding	55.00%
Debt redemption period after equity offering closing	90 days
Senior Notes | 5.375% senior notes due 2027 | Cyrus One LP And Cyrus One Finance Corp
Debt Instrument [Line Items]
Stated interest rate	5.375%
Debt principal amount	$ 300,000,000		300,000,000	300,000,000
Senior Notes | 6.375% senior notes due 2022
Debt Instrument [Line Items]
Long-term debt, net			0	0		$ 474,800,000	477,300,000
Repurchased amount			515,100,000	515,100,000
Repurchased amount, accrued and unpaid interest			10,300,000	10,300,000
Deferred financing costs, bond premium and legal fees write off			6,200,000
Loss on extinguishment of debt			36,200,000
Senior Notes | 6.375% senior notes due 2022 | Cyrus One LP And Cyrus One Finance Corp
Debt Instrument [Line Items]
Stated interest rate										6.375%
Long-term debt, net										$ 525,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Credit agreement amount			$ 1,000,000,000	$ 1,000,000,000
Term of extension option		1 year
Effective interest rate			2.53%	2.53%
Outstanding borrowings credit facility			$ 405,000,000	$ 405,000,000			235,000,000
Commitment fee percent				0.25%
Commitment fee amount				$ 400,000	$ 300,000
Credit facility, available capacity			$ 586,500,000	$ 586,500,000
Maximum percentage of dividends allowed to be distributed			95.00%	95.00%
Revolving Credit Facility | LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate		1.55%
Revolving Credit Facility | Credit Agreement
Debt Instrument [Line Items]
Credit agreement amount		$ 650,000,000
Revolving Credit Facility | First Amended and Restated Credit Agreement
Debt Instrument [Line Items]
Optional additional borrowing capacity		250,000,000
Revolving Credit Facility | Second Amended and Restated Credit Agreement
Debt Instrument [Line Items]
Optional additional borrowing capacity								$ 300,000,000
Credit agreement amount								1,000,000,000
Revolving Credit Facility | Term Loan
Debt Instrument [Line Items]
Deferred financing costs		$ 2,100,000
Outstanding borrowings credit facility			$ 550,000,000	$ 550,000,000			$ 550,000,000
Revolving Credit Facility | Term Loan | Second Amended and Restated Credit Agreement
Debt Instrument [Line Items]
Deferred financing costs								$ 6,600,000

Fair Value of Financial Instr37

Fair Value of Financial Instruments - Carrying Value and Fair Value of Other Financial Instruments (Details) - USD ($) $ in Millions	Mar. 31, 2017	Mar. 30, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	$ 1,731.8		$ 1,240.1
Revolving Credit Facility and Term Loans
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revolving Credit Facility	405		235
Revolving Credit Facility and Term Loans | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revolving Credit Facility	955		785
Revolving Credit Facility and Term Loans | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Revolving Credit Facility	955		785
Senior Notes | 2024 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	500		0
Senior Notes | 2024 Notes | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	500		0
Senior Notes | 2024 Notes | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	511.3		0
Senior Notes | 2027 Notes
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	300		0
Senior Notes | 2027 Notes | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	300		0
Senior Notes | 2027 Notes | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	303.8		0
Senior Notes | 2022 Notes, including bond premium
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	0	$ 474.8	477.3
Senior Notes | 2022 Notes, including bond premium | Carrying Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	0		477.3
Senior Notes | 2022 Notes, including bond premium | Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long-term debt, net	$ 0		$ 502.1

Dividends - Narrative (Details)

Dividends - Narrative (Details)	Feb. 22, 2017$ / shares
Stockholders' Equity Note [Abstract]
Cash dividend payable to stockholders (in dollars per share)	$ 0.42

Stock-Based Compensation Plan39

Stock-Based Compensation Plans - Allocated Share-based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	$ 3.7	$ 3
2013 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	0	0.1
2014 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	0.1	0.3
2015 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	0.8	1.1
2016 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	1.9	1.2
2017 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	0.9	0
Founders
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	$ 0	$ 0.3

Stock-Based Compensation Plan40

Stock-Based Compensation Plans - Narrative (Details) - USD ($)	Feb. 13, 2017	Feb. 01, 2016	Feb. 10, 2015	Feb. 07, 2014	Apr. 17, 2013	Jan. 24, 2013	Mar. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)							8,900,000
Founders | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)						1,000,000
Other than options grant date value						$ 19,000,000
2013 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, other than options							$ 0
2013 Grants | Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage					50.00%
Award vesting period					3 years
2013 Grants | Market based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage					50.00%
Award vesting period					3 years
Measurement period					3 years
2013 Grants | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period for award					10 years
Weighted average exercise price for grants (in dollars per share)					$ 23.58
2014 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, other than options							0
2014 Grants | Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage				50.00%
Award vesting period				3 years
Performance period				3 years
2014 Grants | Market based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage				50.00%
Award vesting period				3 years
2015 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, other than options							$ 1,800,000
Unrecognized compensation expense, period for recognition							5 months 6 days
2015 Grants | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			20.00%
Award vesting period			3 years
2015 Grants | Performance and market based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			80.00%
2015 Grants | Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Measurement period			3 years
Cap on award vesting for first two years			100.00%
2015 Grants | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
2016 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, other than options							$ 12,700,000
Unrecognized compensation expense, period for recognition							1 year 4 months 18 days
2016 Grants | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
2016 Grants | Restricted Stock | Cliff vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
2016 Grants | Performance and market based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Cap on award vesting for first two years		100.00%
2016 Grants | Time and performance based, restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)		$ 36.99
2016 Grants | Market based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)		$ 43.66
2016 Grants | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Expiration period for award		10 years
Option grant date fair value (in dollars per share)		$ 6.99
Weighted average grant date fair value (in dollars per share)		$ 36.99
2017 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, other than options							$ 13,900,000
Cap on award vesting for first two years	100.00%
Unrecognized compensation expense, period for recognition							2 years 3 months 18 days
2017 Grants | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)	18,179
Award vesting period	1 year
2017 Grants | Market based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)	129,146
Award vesting period	3 years
Weighted average grant date fair value (in dollars per share)	$ 63.23
2017 Grants | Time-based restricted stock and units and market-based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options grant date value	$ 14,800,000
2017 Grants | Time-based restricted stock units and restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)	$ 48.13
2017 Grants | Time-based restricted units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Grants in period (in shares)	119,218
Award vesting period	3 years
Term of dividends payable							10 days
LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares available for grant (in shares)							5,900,000
Minimum | 2017 Grants | Market based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance percentage exceeding REIT index causing awards to vest	2.00%
Maximum | 2017 Grants | Market based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance percentage exceeding REIT index causing awards to vest	200.00%

(Loss) Income per Share - Compu

(Loss) Income per Share - Computation of Basic and Diluted Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Numerator:
Net (loss) income attributed to common stockholders	$ (30.4)	$ 5.6
Less: Restricted stock dividends, Basic	(0.2)	(0.2)
Less: Restricted stock dividends, Diluted	(0.2)	(0.2)
Net (loss) income available to stockholders, Basic	(30.6)	5.4
Net (loss) income available to stockholders, Diluted	$ (30.6)	$ 5.4
Denominator:
Weighted average common outstanding - basic (in shares)	84	72.1
Performance-based restricted stock and units (in shares)	0	0.6
Convertible securities (in shares)	0	0.1
Weighted average shares outstanding- diluted (in shares)	84	72.8
EPS:
Net (loss) income per share-basic (in dollars per share)	$ (0.36)	$ 0.07
Net (loss) income per share-diluted (in dollars per share)	$ (0.36)	$ 0.07

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Dec. 31, 2016
Cincinnati Bell Inc.
Related Party Transaction [Line Items]
Ownership %		5.00%
Operating partnership units owned (in shares)		0
Affiliated entity
Related Party Transaction [Line Items]
Revenue from related party	$ 5.3
Expenses to related party	$ 0.5

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details)	3 Months Ended
	Mar. 31, 2017USD ($)Subsidiary	Mar. 31, 2016USD ($)	Dec. 31, 2016USD ($)
Income Taxes [Line Items]
Number of subsidiaries as taxable REIT | Subsidiary	2
Income tax expense	$ (400,000)	$ (200,000)
Deferred tax assets	$ 0		$ 0
Minimum
Income Taxes [Line Items]
Percentage of taxable income to qualify as REIT	90.00%
Maximum
Income Taxes [Line Items]
Percentage of taxable income to qualify as REIT	100.00%

Guarantors - Narrative (Details

Guarantors - Narrative (Details) - USD ($)	Mar. 31, 2017	Mar. 17, 2017
CyrusOne GP
Condensed Financial Statements, Captions [Line Items]
Combined interest held on completion of transactions	1.00%
Ownership percent of senior notes	100.00%
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Parent ownership percentage	100.00%
Senior Notes | 2024 Notes | Cyrus One LP And Cyrus One Finance Corp
Condensed Financial Statements, Captions [Line Items]
Debt principal amount	$ 500,000,000	$ 500,000,000
Senior Notes | 2027 Notes | Cyrus One LP And Cyrus One Finance Corp
Condensed Financial Statements, Captions [Line Items]
Debt principal amount	$ 300,000,000	$ 300,000,000

Guarantors - Consolidating Bala

Guarantors - Consolidating Balance Sheets (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Condensed Consolidating Balance Sheets
Land	$ 156.9	$ 142.7
Buildings and improvements	1,270.9	1,008.9
Equipment	1,438	1,042.9
Construction in progress	371.7	407.1
Subtotal	3,237.5	2,601.6
Accumulated depreciation	(625.9)	(578.5)
Net investment in real estate	2,611.6	2,023.1
Cash and cash equivalents	20.4	14.6	$ 87.7	$ 14.3
Investment in subsidiaries	0	0
Restricted cash	0.6	0
Rent and other receivables, net	89.4	83.3
Intercompany receivable	0	0
Goodwill	455.1	455.1
Intangible assets, net	223.1	150.2
Other assets	143.6	126.1
Total assets	3,543.8	2,852.4
Accounts payable and accrued expenses	268.2	227.1
Deferred revenue	93.3	76.7
Intercompany payable	0	0
Capital lease obligations	12.4	10.8
Long-term debt, net	1,731.8	1,240.1
Lease financing arrangements	134.5	135.7
Total liabilities	2,240.2	1,690.4
Total stockholders’ equity	1,303.6	1,162
Total liabilities and equity	3,543.8	2,852.4
Eliminations/Consolidations
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	1.3	1.2
Equipment	5.4	5.1
Construction in progress	2.3	0.7
Subtotal	9	7
Accumulated depreciation	0	0
Net investment in real estate	9	7
Cash and cash equivalents	0	0	0	0
Investment in subsidiaries	(2,940.2)	(2,560.1)
Restricted cash	0
Rent and other receivables, net	0	0
Intercompany receivable	(1,475.8)	(1,076.8)
Goodwill	0	0
Intangible assets, net	0	0
Other assets	0	0
Total assets	(4,407)	(3,629.9)
Accounts payable and accrued expenses	0	0
Deferred revenue	0	0
Intercompany payable	(1,475.8)	(1,076.8)
Capital lease obligations	0	0
Long-term debt, net	0	0
Lease financing arrangements	0	0
Total liabilities	(1,475.8)	(1,076.8)
Total stockholders’ equity	(2,931.2)	(2,553.1)
Total liabilities and equity	(4,407)	(3,629.9)
General Partner
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	0	0
Equipment	0	0
Construction in progress	0	0
Subtotal	0	0
Accumulated depreciation	0	0
Net investment in real estate	0	0
Cash and cash equivalents	0	0	0	0
Investment in subsidiaries	13.2	11.7
Restricted cash	0
Rent and other receivables, net	0	0
Intercompany receivable	0	0
Goodwill	0	0
Intangible assets, net	0	0
Other assets	0	0
Total assets	13.2	11.7
Accounts payable and accrued expenses	0	0
Deferred revenue	0	0
Intercompany payable	0	0
Capital lease obligations	0	0
Long-term debt, net	0	0
Lease financing arrangements	0	0
Total liabilities	0	0
Total stockholders’ equity	13.2	11.7
Total liabilities and equity	13.2	11.7
Parent Guarantor
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	0	0
Equipment	0	0
Construction in progress	0	0
Subtotal	0	0
Accumulated depreciation	0	0
Net investment in real estate	0	0
Cash and cash equivalents	0	0	0.2	0
Investment in subsidiaries	1,316.1	1,170.3
Restricted cash	0
Rent and other receivables, net	0	0
Intercompany receivable	16.2	18.6
Goodwill	0	0
Intangible assets, net	0	0
Other assets	0	0
Total assets	1,332.3	1,188.9
Accounts payable and accrued expenses	37.7	33.9
Deferred revenue	0	0
Intercompany payable	0	0
Capital lease obligations	0	0
Long-term debt, net	0	0
Lease financing arrangements	0	0
Total liabilities	37.7	33.9
Total stockholders’ equity	1,294.6	1,155
Total liabilities and equity	1,332.3	1,188.9
LP Co-issuer
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	0	0
Equipment	0	0
Construction in progress	0	0
Subtotal	0	0
Accumulated depreciation	0	0
Net investment in real estate	0	0
Cash and cash equivalents	0	0	0	0
Investment in subsidiaries	1,609.3	1,376.1
Restricted cash	0
Rent and other receivables, net	0	0
Intercompany receivable	1,459.1	1,057.7
Goodwill	0	0
Intangible assets, net	0	0
Other assets	0	0
Total assets	3,068.4	2,433.8
Accounts payable and accrued expenses	4.3	4.8
Deferred revenue	0	0
Intercompany payable	16.2	18.6
Capital lease obligations	0	0
Long-term debt, net	1,731.8	1,240.1
Lease financing arrangements	0	0
Total liabilities	1,752.3	1,263.5
Total stockholders’ equity	1,316.1	1,170.3
Total liabilities and equity	3,068.4	2,433.8
Finance Co-issuer
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	0	0
Equipment	0	0
Construction in progress	0	0
Subtotal	0	0
Accumulated depreciation	0	0
Net investment in real estate	0	0
Cash and cash equivalents	0	0	0	0
Investment in subsidiaries	0	0
Restricted cash	0
Rent and other receivables, net	0	0
Intercompany receivable	0	0
Goodwill	0	0
Intangible assets, net	0	0
Other assets	0	0
Total assets	0	0
Accounts payable and accrued expenses	0	0
Deferred revenue	0	0
Intercompany payable	0	0
Capital lease obligations	0	0
Long-term debt, net	0	0
Lease financing arrangements	0	0
Total liabilities	0	0
Total stockholders’ equity	0	0
Total liabilities and equity	0	0
Guarantor Subsidiaries
Condensed Consolidating Balance Sheets
Land	156.9	142.7
Buildings and improvements	1,234.8	973.6
Equipment	1,431.6	1,036.8
Construction in progress	369.4	406.4
Subtotal	3,192.7	2,559.5
Accumulated depreciation	(618.1)	(571.3)
Net investment in real estate	2,574.6	1,988.2
Cash and cash equivalents	18.1	13.4	84.6	10.4
Investment in subsidiaries	1.6	2
Restricted cash	0.6
Rent and other receivables, net	88	81.8
Intercompany receivable	0	0
Goodwill	455.1	455.1
Intangible assets, net	223.1	150.2
Other assets	141.1	123.4
Total assets	3,502.2	2,814.1
Accounts payable and accrued expenses	224.5	187.7
Deferred revenue	92.6	76
Intercompany payable	1,459.6	1,058.2
Capital lease obligations	7.2	5.6
Long-term debt, net	0	0
Lease financing arrangements	109	110.5
Total liabilities	1,892.9	1,438
Total stockholders’ equity	1,609.3	1,376.1
Total liabilities and equity	3,502.2	2,814.1
Non- Guarantors
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	34.8	34.1
Equipment	1	1
Construction in progress	0	0
Subtotal	35.8	35.1
Accumulated depreciation	(7.8)	(7.2)
Net investment in real estate	28	27.9
Cash and cash equivalents	2.3	1.2	$ 2.9	$ 3.9
Investment in subsidiaries	0	0
Restricted cash	0
Rent and other receivables, net	1.4	1.5
Intercompany receivable	0.5	0.5
Goodwill	0	0
Intangible assets, net	0	0
Other assets	2.5	2.7
Total assets	34.7	33.8
Accounts payable and accrued expenses	1.7	0.7
Deferred revenue	0.7	0.7
Intercompany payable	0	0
Capital lease obligations	5.2	5.2
Long-term debt, net	0	0
Lease financing arrangements	25.5	25.2
Total liabilities	33.1	31.8
Total stockholders’ equity	1.6	2
Total liabilities and equity	$ 34.7	$ 33.8

Guarantors - Consolidating Stat

Guarantors - Consolidating Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenue:
Base revenue and other	$ 134.2	$ 106.5
Metered power reimbursements	15.1	11.3
Revenue	149.3	117.8
Costs and expenses:
Property operating expenses	52.3	40.3
Sales and marketing	4.9	4
General and administrative	15.8	14
Depreciation and amortization	55.7	39.3
Transaction and acquisition integration costs	0.6	2.3
Loss on disposal	0.2	0
Total costs and expenses	129.5	99.9
Operating income	19.8	17.9
Interest expense	13.6	12.1
Loss on extinguishment of debt	36.2	0
Net (loss) income before income taxes	(30)	5.8
Income tax expense	(0.4)	(0.2)
Equity (loss) earnings related to investment in subsidiaries	0	0
Net (loss) income	(30.4)	5.6
Noncontrolling interest in net (loss) income	0
Net (loss) income attributed to common stockholders	(30.4)	5.6
Other comprehensive loss	0	0
Comprehensive (loss) income attributable to CyrusOne Inc.	(30.4)	5.6
Eliminations/Consolidations
Revenue:
Base revenue and other	0	0
Metered power reimbursements	0	0
Revenue	0	0
Costs and expenses:
Property operating expenses	0	0
Sales and marketing	0	0
General and administrative	0	0
Depreciation and amortization	0	0
Transaction and acquisition integration costs	0	0
Loss on disposal	0
Total costs and expenses	0	0
Operating income	0	0
Interest expense	(2)	(0.4)
Loss on extinguishment of debt	0
Net (loss) income before income taxes	2	0.4
Income tax expense	0	0
Equity (loss) earnings related to investment in subsidiaries	14.3	(21.5)
Net (loss) income	16.3	(21.1)
Noncontrolling interest in net (loss) income	0
Net (loss) income attributed to common stockholders	16.3	(21.1)
Other comprehensive loss	0	0
Comprehensive (loss) income attributable to CyrusOne Inc.	16.3	(21.1)
General Partner
Revenue:
Base revenue and other	0	0
Metered power reimbursements	0	0
Revenue	0	0
Costs and expenses:
Property operating expenses	0	0
Sales and marketing	0	0
General and administrative	0	0
Depreciation and amortization	0	0
Transaction and acquisition integration costs	0	0
Loss on disposal	0
Total costs and expenses	0	0
Operating income	0	0
Interest expense	0	0
Loss on extinguishment of debt	0
Net (loss) income before income taxes	0	0
Income tax expense	0	0
Equity (loss) earnings related to investment in subsidiaries	(0.3)	0.1
Net (loss) income	(0.3)	0.1
Noncontrolling interest in net (loss) income	0
Net (loss) income attributed to common stockholders	(0.3)	0.1
Other comprehensive loss	0	0
Comprehensive (loss) income attributable to CyrusOne Inc.	(0.3)	0.1
Parent Guarantor
Revenue:
Base revenue and other	0	0
Metered power reimbursements	0	0
Revenue	0	0
Costs and expenses:
Property operating expenses	0	0
Sales and marketing	0	0
General and administrative	0	0
Depreciation and amortization	0	0
Transaction and acquisition integration costs	0	0
Loss on disposal	0
Total costs and expenses	0	0
Operating income	0	0
Interest expense	0	0
Loss on extinguishment of debt	0
Net (loss) income before income taxes	0	0
Income tax expense	0	0
Equity (loss) earnings related to investment in subsidiaries	(32.4)	5.2
Net (loss) income	(32.4)	5.2
Noncontrolling interest in net (loss) income	0
Net (loss) income attributed to common stockholders	(32.4)	5.2
Other comprehensive loss	0	0
Comprehensive (loss) income attributable to CyrusOne Inc.	(32.4)	5.2
LP Co-issuer
Revenue:
Base revenue and other	0	0
Metered power reimbursements	0	0
Revenue	0	0
Costs and expenses:
Property operating expenses	0	0
Sales and marketing	0	0
General and administrative	0	0
Depreciation and amortization	0	0
Transaction and acquisition integration costs	0	0
Loss on disposal	0
Total costs and expenses	0	0
Operating income	0	0
Interest expense	15	11.7
Loss on extinguishment of debt	36.2
Net (loss) income before income taxes	(51.2)	(11.7)
Income tax expense	0	0
Equity (loss) earnings related to investment in subsidiaries	18.8	16.9
Net (loss) income	(32.4)	5.2
Noncontrolling interest in net (loss) income	0
Net (loss) income attributed to common stockholders	(32.4)	5.2
Other comprehensive loss	0	0
Comprehensive (loss) income attributable to CyrusOne Inc.	(32.4)	5.2
Finance Co-issuer
Revenue:
Base revenue and other	0	0
Metered power reimbursements	0	0
Revenue	0	0
Costs and expenses:
Property operating expenses	0	0
Sales and marketing	0	0
General and administrative	0	0
Depreciation and amortization	0	0
Transaction and acquisition integration costs	0	0
Loss on disposal	0
Total costs and expenses	0	0
Operating income	0	0
Interest expense	0	0
Loss on extinguishment of debt	0
Net (loss) income before income taxes	0	0
Income tax expense	0	0
Equity (loss) earnings related to investment in subsidiaries	0	0
Net (loss) income	0	0
Noncontrolling interest in net (loss) income	0
Net (loss) income attributed to common stockholders	0	0
Other comprehensive loss	0	0
Comprehensive (loss) income attributable to CyrusOne Inc.	0	0
Guarantor Subsidiaries
Revenue:
Base revenue and other	133.3	105.4
Metered power reimbursements	14.8	11
Revenue	148.1	116.4
Costs and expenses:
Property operating expenses	51.7	39.7
Sales and marketing	4.9	4
General and administrative	15.8	14
Depreciation and amortization	55.3	38.6
Transaction and acquisition integration costs	0.6	2.3
Loss on disposal	0.2
Total costs and expenses	128.5	98.6
Operating income	19.6	17.8
Interest expense	0	0
Loss on extinguishment of debt	0
Net (loss) income before income taxes	19.6	17.8
Income tax expense	(0.4)	(0.2)
Equity (loss) earnings related to investment in subsidiaries	(0.4)	(0.7)
Net (loss) income	18.8	16.9
Noncontrolling interest in net (loss) income	0
Net (loss) income attributed to common stockholders	18.8	16.9
Other comprehensive loss	0	0
Comprehensive (loss) income attributable to CyrusOne Inc.	18.8	16.9
Non- Guarantors
Revenue:
Base revenue and other	0.9	1.1
Metered power reimbursements	0.3	0.3
Revenue	1.2	1.4
Costs and expenses:
Property operating expenses	0.6	0.6
Sales and marketing	0	0
General and administrative	0	0
Depreciation and amortization	0.4	0.7
Transaction and acquisition integration costs	0	0
Loss on disposal	0
Total costs and expenses	1	1.3
Operating income	0.2	0.1
Interest expense	0.6	0.8
Loss on extinguishment of debt	0
Net (loss) income before income taxes	(0.4)	(0.7)
Income tax expense	0	0
Equity (loss) earnings related to investment in subsidiaries	0	0
Net (loss) income	(0.4)	(0.7)
Noncontrolling interest in net (loss) income	0
Net (loss) income attributed to common stockholders	(0.4)	(0.7)
Other comprehensive loss	0	0
Comprehensive (loss) income attributable to CyrusOne Inc.	$ (0.4)	$ (0.7)

Guarantors - Consolidating St47

Guarantors - Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed Consolidating Statements of Cash Flows
Net (loss) income	$ (30.4)	$ 5.6
Equity (loss) earnings related to investment in subsidiaries	0	0
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	55.7	39.3
Non-cash interest expense and change in interest accrual	(1)	0.9
Stock-based compensation expense	3.7	3
Provision for bad debt	0	0.1
Loss on extinguishment of debt	36.2	0
Loss on disposal	0.2	0
Change in operating assets and liabilities:
Rent receivables and other assets	(20)	6.2
Accounts payable and accrued expenses	(4.9)	0
Deferred revenues	15.7	(2.3)
Net cash provided by operating activities	55.2	52.8
Cash flows from investing activities:
Capital expenditures – asset acquisitions, net of cash acquired	(492.3)	(131.1)
Capital expenditures – other development	(182.5)	(78.5)
Investment in subsidiaries	0	0
Changes in restricted cash	(0.6)	0.8
Return of investment	0	0
Intercompany borrowings	0	0
Net cash used in investing activities	(675.4)	(208.8)
Cash flows from financing activities:
Issuance of common stock	211	256
Dividends paid	(32.4)	(22.8)
Intercompany borrowings	0	0
Borrowings from credit facility	440	320
Proceeds from issuance of debt	800	0
Payments on credit facility	(270)	(305)
Payments on senior notes	(474.8)	0
Payments on capital leases and lease financing arrangements	(2.3)	(3.1)
Tax payment upon exercise of equity awards	(6.4)	(13.6)
Contributions/distributions from parent	0	0
Debt issuance costs	(8.8)	(2.1)
Payment of debt extinguishment costs	(30.3)	0
Net cash provided by financing activities	626	229.4
Net increase in cash and cash equivalents	5.8	73.4
Cash and cash equivalents at beginning of period	14.6	14.3
Cash and cash equivalents at end of period	20.4	87.7
General Partner
Condensed Consolidating Statements of Cash Flows
Net (loss) income	(0.3)	0.1
Equity (loss) earnings related to investment in subsidiaries	0.3	(0.1)
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	0	0
Non-cash interest expense and change in interest accrual	0	0
Stock-based compensation expense	0	0
Provision for bad debt	0	0
Loss on extinguishment of debt	0
Loss on disposal	0
Change in operating assets and liabilities:
Rent receivables and other assets	0	0
Accounts payable and accrued expenses	0	0
Deferred revenues	0	0
Net cash provided by operating activities	0	0
Cash flows from investing activities:
Capital expenditures – asset acquisitions, net of cash acquired	0	0
Capital expenditures – other development	0	0
Investment in subsidiaries	(2.1)	(2.6)
Changes in restricted cash	0	0
Return of investment	0	0
Intercompany borrowings	0	0
Net cash used in investing activities	(2.1)	(2.6)
Cash flows from financing activities:
Issuance of common stock	0	0
Dividends paid	0	0
Intercompany borrowings	0	0
Borrowings from credit facility	0	0
Proceeds from issuance of debt	0
Payments on credit facility	0	0
Payments on senior notes	0
Payments on capital leases and lease financing arrangements	0	0
Tax payment upon exercise of equity awards	0	0
Contributions/distributions from parent	2.1	2.6
Debt issuance costs	0	0
Payment of debt extinguishment costs	0
Net cash provided by financing activities	2.1	2.6
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Eliminations/Consolidations
Condensed Consolidating Statements of Cash Flows
Net (loss) income	16.3	(21.1)
Equity (loss) earnings related to investment in subsidiaries	(14.3)	21.5
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	0	0
Non-cash interest expense and change in interest accrual	0	0
Stock-based compensation expense	0	0
Provision for bad debt	0	0
Loss on extinguishment of debt	0
Loss on disposal	0
Change in operating assets and liabilities:
Rent receivables and other assets	0	0
Accounts payable and accrued expenses	0	0
Deferred revenues	0	0
Net cash provided by operating activities	2	0.4
Cash flows from investing activities:
Capital expenditures – asset acquisitions, net of cash acquired	0	0
Capital expenditures – other development	(2)	0
Investment in subsidiaries	423.7	514
Changes in restricted cash	0	0
Return of investment	(32.4)	(20.8)
Intercompany borrowings	395.3	(40.6)
Net cash used in investing activities	784.6	452.6
Cash flows from financing activities:
Issuance of common stock	0	0
Dividends paid	32.4	20.8
Intercompany borrowings	(395.3)	40.2
Borrowings from credit facility	0	0
Proceeds from issuance of debt	0
Payments on credit facility	0	0
Payments on senior notes	0
Payments on capital leases and lease financing arrangements	0	0
Tax payment upon exercise of equity awards	0	0
Contributions/distributions from parent	(423.7)	(514)
Debt issuance costs	0	0
Payment of debt extinguishment costs	0
Net cash provided by financing activities	(786.6)	(453)
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Parent Guarantor
Condensed Consolidating Statements of Cash Flows
Net (loss) income	(32.4)	5.2
Equity (loss) earnings related to investment in subsidiaries	32.4	(5.2)
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	0	0
Non-cash interest expense and change in interest accrual	0	0
Stock-based compensation expense	0	0
Provision for bad debt	0	0
Loss on extinguishment of debt	0
Loss on disposal	0
Change in operating assets and liabilities:
Rent receivables and other assets	0	0
Accounts payable and accrued expenses	0	0
Deferred revenues	0	0
Net cash provided by operating activities	0	0
Cash flows from investing activities:
Capital expenditures – asset acquisitions, net of cash acquired	0	0
Capital expenditures – other development	0	0
Investment in subsidiaries	(210.8)	(255.7)
Changes in restricted cash	0	0
Return of investment	32.4	20.8
Intercompany borrowings	6.2	13.5
Net cash used in investing activities	(172.2)	(221.4)
Cash flows from financing activities:
Issuance of common stock	211	256
Dividends paid	(32.4)	(20.8)
Intercompany borrowings	0	0
Borrowings from credit facility	0	0
Proceeds from issuance of debt	0
Payments on credit facility	0	0
Payments on senior notes	0
Payments on capital leases and lease financing arrangements	0	0
Tax payment upon exercise of equity awards	(6.4)	(13.6)
Contributions/distributions from parent	0	0
Debt issuance costs	0	0
Payment of debt extinguishment costs	0
Net cash provided by financing activities	172.2	221.6
Net increase in cash and cash equivalents	0	0.2
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0.2
LP Co-issuer
Condensed Consolidating Statements of Cash Flows
Net (loss) income	(32.4)	5.2
Equity (loss) earnings related to investment in subsidiaries	(18.8)	(16.9)
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	0	0
Non-cash interest expense and change in interest accrual	(1)	0.9
Stock-based compensation expense	0	0
Provision for bad debt	0	0
Loss on extinguishment of debt	36.2
Loss on disposal	0
Change in operating assets and liabilities:
Rent receivables and other assets	0	0
Accounts payable and accrued expenses	0	7.1
Deferred revenues	0	0
Net cash provided by operating activities	(16)	(3.7)
Cash flows from investing activities:
Capital expenditures – asset acquisitions, net of cash acquired	0	0
Capital expenditures – other development	0	0
Investment in subsidiaries	(210.8)	(255.7)
Changes in restricted cash	0	0
Return of investment	0	0
Intercompany borrowings	(401.5)	27.1
Net cash used in investing activities	(612.3)	(228.6)
Cash flows from financing activities:
Issuance of common stock	0	0
Dividends paid	(32.4)	(22.8)
Intercompany borrowings	(6.2)	(13.5)
Borrowings from credit facility	440	320
Proceeds from issuance of debt	800
Payments on credit facility	(270)	(305)
Payments on senior notes	(474.8)
Payments on capital leases and lease financing arrangements	0	0
Tax payment upon exercise of equity awards	0	0
Contributions/distributions from parent	210.8	255.7
Debt issuance costs	(8.8)	(2.1)
Payment of debt extinguishment costs	(30.3)
Net cash provided by financing activities	628.3	232.3
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Finance Co-issuer
Condensed Consolidating Statements of Cash Flows
Net (loss) income	0	0
Equity (loss) earnings related to investment in subsidiaries	0	0
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	0	0
Non-cash interest expense and change in interest accrual	0	0
Stock-based compensation expense	0	0
Provision for bad debt	0	0
Loss on extinguishment of debt	0
Loss on disposal	0
Change in operating assets and liabilities:
Rent receivables and other assets	0	0
Accounts payable and accrued expenses	0	0
Deferred revenues	0	0
Net cash provided by operating activities	0	0
Cash flows from investing activities:
Capital expenditures – asset acquisitions, net of cash acquired	0	0
Capital expenditures – other development	0	0
Investment in subsidiaries	0	0
Changes in restricted cash	0	0
Return of investment	0	0
Intercompany borrowings	0	0
Net cash used in investing activities	0	0
Cash flows from financing activities:
Issuance of common stock	0	0
Dividends paid	0	0
Intercompany borrowings	0	0
Borrowings from credit facility	0	0
Proceeds from issuance of debt	0
Payments on credit facility	0	0
Payments on senior notes	0
Payments on capital leases and lease financing arrangements	0	0
Tax payment upon exercise of equity awards	0	0
Contributions/distributions from parent	0	0
Debt issuance costs	0	0
Payment of debt extinguishment costs	0
Net cash provided by financing activities	0	0
Net increase in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Guarantor Subsidiaries
Condensed Consolidating Statements of Cash Flows
Net (loss) income	18.8	16.9
Equity (loss) earnings related to investment in subsidiaries	0.4	0.7
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	55.3	38.6
Non-cash interest expense and change in interest accrual	0	0
Stock-based compensation expense	3.7	3
Provision for bad debt	0	0.1
Loss on extinguishment of debt	0
Loss on disposal	0.2
Change in operating assets and liabilities:
Rent receivables and other assets	(20.3)	6
Accounts payable and accrued expenses	(5.9)	(7.1)
Deferred revenues	15.7	(2.2)
Net cash provided by operating activities	67.9	56
Cash flows from investing activities:
Capital expenditures – asset acquisitions, net of cash acquired	(492.3)	(131.1)
Capital expenditures – other development	(180.5)	(78.5)
Investment in subsidiaries	0	0
Changes in restricted cash	(0.6)	0.8
Return of investment	0	0
Intercompany borrowings	0	0
Net cash used in investing activities	(673.4)	(208.8)
Cash flows from financing activities:
Issuance of common stock	0	0
Dividends paid	0	0
Intercompany borrowings	401.5	(26.7)
Borrowings from credit facility	0	0
Proceeds from issuance of debt	0
Payments on credit facility	0	0
Payments on senior notes	0
Payments on capital leases and lease financing arrangements	(2.1)	(2)
Tax payment upon exercise of equity awards	0	0
Contributions/distributions from parent	210.8	255.7
Debt issuance costs	0	0
Payment of debt extinguishment costs	0
Net cash provided by financing activities	610.2	227
Net increase in cash and cash equivalents	4.7	74.2
Cash and cash equivalents at beginning of period	13.4	10.4
Cash and cash equivalents at end of period	18.1	84.6
Non- Guarantors
Condensed Consolidating Statements of Cash Flows
Net (loss) income	(0.4)	(0.7)
Equity (loss) earnings related to investment in subsidiaries	0	0
Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities:
Depreciation and amortization	0.4	0.7
Non-cash interest expense and change in interest accrual	0	0
Stock-based compensation expense	0	0
Provision for bad debt	0	0
Loss on extinguishment of debt	0
Loss on disposal	0
Change in operating assets and liabilities:
Rent receivables and other assets	0.3	0.2
Accounts payable and accrued expenses	1	0
Deferred revenues	0	(0.1)
Net cash provided by operating activities	1.3	0.1
Cash flows from investing activities:
Capital expenditures – asset acquisitions, net of cash acquired	0	0
Capital expenditures – other development	0	0
Investment in subsidiaries	0	0
Changes in restricted cash	0	0
Return of investment	0	0
Intercompany borrowings	0	0
Net cash used in investing activities	0	0
Cash flows from financing activities:
Issuance of common stock	0	0
Dividends paid	0	0
Intercompany borrowings	0	0
Borrowings from credit facility	0	0
Proceeds from issuance of debt	0
Payments on credit facility	0	0
Payments on senior notes	0
Payments on capital leases and lease financing arrangements	(0.2)	(1.1)
Tax payment upon exercise of equity awards	0	0
Contributions/distributions from parent	0	0
Debt issuance costs	0	0
Payment of debt extinguishment costs	0
Net cash provided by financing activities	(0.2)	(1.1)
Net increase in cash and cash equivalents	1.1	(1)
Cash and cash equivalents at beginning of period	1.2	3.9
Cash and cash equivalents at end of period	$ 2.3	$ 2.9

Subsequent Events (Details)

Subsequent Events (Details)	May 09, 2017a
Subsequent event
Subsequent Event [Line Items]
Area of land (in acres)	48