CyrusOne (CONE) 10-K 22 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2018	Feb. 14, 2019	Jun. 30, 2018
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Trading Symbol	CONE
Entity Registrant Name	CyrusOne Inc.
Entity Central Index Key	1,553,023
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		108,257,818
Entity Public Float			$ 5.8

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Investment in real estate:
Land	$ 118.5	$ 104.6
Buildings and improvements	1,677.5	1,371.4
Equipment	2,630.2	1,813.9
Gross operating real estate	4,426.2	3,289.9
Less accumulated depreciation	(1,054.5)	(782.4)
Net operating real estate	3,371.7	2,507.5
Construction in progress, including land under development	744.9	487.1
Land held for future development	176.4	63.8
Total investment in real estate, net	4,293	3,058.4
Cash and cash equivalents	64.4	151.9
Rent and other receivables (net of allowance for doubtful accounts of $1.7 and $2.1 as of December 31, 2018 and December 31, 2017, respectively)	106.2	87.2
Equity investments	198.1	175.6
Goodwill	455.1	455.1
Intangible assets (net of accumulated amortization of $166.9 and $136.1 as of December 31, 2018 and December 31, 2017, respectively)	235.7	203
Other assets	240	180.9
Total assets	5,592.5	4,312.1
Liabilities and equity
Debt, net	2,624.7	2,089.4
Capital lease obligations and lease financing arrangements	156.7	142
Construction costs payable	195.3	115.5
Accounts payable and accrued expenses	121.3	97.9
Dividends payable	51	41.8
Deferred revenue and prepaid rents	148.6	111.6
Deferred tax liability	68.9	0
Total liabilities	3,366.5	2,598.2
Commitment and contingencies
Stockholders' 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 108,329,314 and 96,137,874 shares issued and outstanding at December 31, 2018 and December 31, 2017, respectively	1.1	1
Additional paid in capital	2,837.4	2,125.6
Accumulated deficit	(600.2)	(486.9)
Accumulated other comprehensive income (loss)	(12.3)	74.2
Total stockholders’ equity	2,226	1,713.9
Noncontrolling interest	0	0
Total equity	2,226	1,713.9
Total liabilities and equity	$ 5,592.5	$ 4,312.1

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 1.7	$ 2.1
Accumulated amortization of intangible assets	$ 166.9	$ 136.1
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)	108,329,314	96,137,874
Common stock outstanding (in shares)	108,329,314	96,137,874

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue:
Revenue	$ 821,400,000	$ 672,000,000	$ 529,100,000
Operating expenses:
Property operating expenses	292,400,000	235,100,000	187,500,000
Sales and marketing	19,600,000	17,000,000	16,900,000
General and administrative	80,600,000	67,000,000	60,700,000
Depreciation and amortization	334,100,000	258,900,000	183,900,000
Transaction, acquisition, integration and other related expenses	5,000,000	11,900,000	4,600,000
Impairment losses	0	58,000,000	5,000,000
Total operating expenses	731,700,000	647,900,000	458,600,000
Operating income	89,700,000	24,100,000	70,500,000
Interest expense	(94,700,000)	(68,100,000)	(48,800,000)
Unrealized gain on marketable equity investment	9,900,000	0	0
Loss on early extinguishment of debt	(3,100,000)	(36,500,000)	0
Net income (loss) before income taxes	1,800,000	(80,500,000)	21,700,000
Income tax expense	(600,000)	(3,000,000)	(1,800,000)
Net income (loss)	$ 1,200,000	$ (83,500,000)	$ 19,900,000
Weighted average number of common shares outstanding - basic (in shares)	99.8	88.9	78.3
Weighted average number of common shares outstanding - diluted (in shares)	100.4	88.9	79
Income (loss) per share - basic (in dollars per share)	$ 0	$ (0.95)	$ 0.24
Income (loss) per share - diluted (in dollars per share)	$ 0	$ (0.95)	$ 0.24

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (105.8)	$ (42.4)	$ 105.9	$ 43.5	$ 2.8	$ (55.1)	$ (0.8)	$ (30.4)	$ 1.2	$ (83.5)	$ 19.9
Other comprehensive income (loss):
Foreign currency translation adjustment									(10.9)	(0.1)	(0.9)
Unrealized gain on equity investment									0	75.6	0
Comprehensive income (loss)									$ (9.7)	$ (8)	$ 19

Consolidated Statements of Equi

Consolidated Statements of Equity - USD ($) shares in Millions, $ in Millions	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income (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)	$ 19.9			19.9		19.9
Foreign currency translation adjustment	(0.9)				(0.9)	(0.9)
Stock-based compensation expense (in shares)		0.6
Stock-based compensation expense			12.3			12.3
Tax payment upon exercise of equity awards (in shares)		(0.5)
Tax payment upon exercise of equity awards			(14.2)			(14.2)
Issuance of common stock, net (in shares)		10.8
Issuance of common stock, net		$ 0.1	447			447.1
Unrealized gain on equity investment	0
Dividends declared				(123.8)		(123.8)
Ending Balance (in shares) at Dec. 31, 2016		83.5
Ending 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)	(83.5)			(83.5)		(83.5)
Foreign currency translation adjustment	$ (0.1)				(0.1)	(0.1)
Stock-based compensation expense (in shares)		(0.1)
Stock-based compensation expense			14.7			14.7
Tax payment upon exercise of equity awards (in shares)		(0.1)
Tax payment upon exercise of equity awards			(6.9)			(6.9)
Issuance of common stock, net (in shares)	12.8	12.8
Issuance of common stock, net		$ 0.2	705.5			705.7
Unrealized gain on equity investment	$ 75.6				75.6	75.6
Dividends declared				(153.6)		(153.6)
Ending Balance (in shares) at Dec. 31, 2017		96.1
Ending Balance at Dec. 31, 2017	1,713.9	$ 1	2,125.6	(486.9)	74.2	1,713.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1.2			1.2		1.2
Foreign currency translation adjustment	$ (10.9)				(10.9)	(10.9)
Stock-based compensation expense (in shares)		0
Stock-based compensation expense			17.5			17.5
Tax payment upon exercise of equity awards (in shares)		(0.1)
Tax payment upon exercise of equity awards			(5.2)			(5.2)
Issuance of common stock, net (in shares)	12.2	12.3
Issuance of common stock, net		$ 0.1	699.5			699.6
Unrealized gain on equity investment	$ 0
Dividends declared				(190.4)		(190.4)
Ending Balance (in shares) at Dec. 31, 2018		108.3
Ending Balance at Dec. 31, 2018	$ 2,226	$ 1.1	$ 2,837.4	$ (600.2)	$ (12.3)	$ 2,226

Consolidated Statements of Eq_2

Consolidated Statements of Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Dividends declared per share (in dollars per share)	$ 1.84	$ 1.68	$ 1.52

Consolidated Statements of Cash

Consolidated Statements of Cash Flows	12 Months Ended
	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Statement of Cash Flows [Abstract]
Net income (loss)	$ 1,200,000	$ (83,500,000)	$ 19,900,000
Adjustments to reconcile net income (loss)to net cash provided by operating activities:
Depreciation and amortization	334,100,000	258,900,000	183,900,000
Provision for bad debt expense	2,600,000	200,000	1,600,000
Impairment losses	0	58,000,000	5,000,000
Unrealized gain on marketable equity investment	(9,900,000)	0	0
Loss on early extinguishment of debt	3,100,000	36,500,000	0
Interest expense amortization, net	4,000,000	4,200,000	4,900,000
Stock-based compensation expense	17,500,000	14,700,000	12,300,000
Other	(600,000)	1,500,000	300,000
Change in operating assets and liabilities:
Rent and other receivables, net and other assets	(80,200,000)	(64,300,000)	(51,700,000)
Accounts payable and accrued expenses	3,000,000	29,300,000	6,900,000
Deferred revenue and prepaid rents	34,500,000	34,000,000	(2,500,000)
Net cash provided by operating activities	309,300,000	289,500,000	180,600,000
Cash flows from investing activities:
Asset acquisitions, primarily real estate, net of cash acquired	(462,800,000)	(492,300,000)	(131,100,000)
Investment in real estate	(865,700,000)	(914,500,000)	(600,000,000)
Equity investments	(12,600,000)	(100,000,000)	0
Net cash used in investing activities	(1,341,100,000)	(1,506,800,000)	(731,100,000)
Cash flows from financing activities:
Issuance of common stock, net	699,600,000	705,700,000	447,100,000
Dividends paid	(181,100,000)	(145,700,000)	(114,300,000)
Proceeds from debt, net	1,988,300,000	2,558,400,000	701,300,000
Payments on debt	(1,547,400,000)	(1,749,800,000)	(461,500,000)
Payments on capital lease obligations and lease financing arrangements	(9,500,000)	(9,800,000)	(9,100,000)
Interest paid by lenders on issuance of the senior notes	0	2,700,000	0
Tax payment upon exercise of equity awards	(5,200,000)	(6,900,000)	(14,200,000)
Net cash provided by financing activities	944,700,000	1,354,600,000	549,300,000
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(400,000)	0	0
Net increase (decrease) in cash, cash equivalents and restricted cash	(87,500,000)	137,300,000	(1,200,000)
Cash, cash equivalents and restricted cash at beginning of period	151,900,000	14,600,000	15,800,000
Cash, cash equivalents and restricted cash at end of period	64,400,000	151,900,000	14,600,000
Supplemental disclosure of cash flow information:
Cash paid for interest, including amounts capitalized of $24.4 million, $17.0 million and $10.6 million in 2018, 2017 and 2016, respectively	115,400,000	68,800,000	55,000,000
Cash paid for income taxes	3,400,000	2,200,000	1,200,000
Non-cash investing and financing activities:
Construction costs and other payables	195,300,000	115,500,000	132,700,000
Dividends payable	51,000,000	41,800,000	33,900,000
Debt assumed in asset acquisition	86,300,000	0	0
Capital lease obligation assumed	$ 25,000,000	$ 2,200,000	$ 0

Consolidated Statements of Ca_2

Consolidated Statements of Cash Flows (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Cash Flows [Abstract]
Capitalized interest	$ 24.4	$ 17	$ 10.6

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements are prepared on a consolidated basis. In addition, the accompanying financial statements have been prepared in accordance with generally accepted accounting principles in the U.S. (GAAP) and include the accounts of the Company, as well as all wholly-owned subsidiaries and any consolidated variable interest entities. All intercompany transactions and balances have been eliminated in consolidation.

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business CyrusOne Inc., together with CyrusOne GP (the "General Partner"), 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 and single-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 48 data centers and two recovery centers located in the United States, United Kingdom, Germany and Singapore. On January 24, 2013 , the Company completed its initial public offering (the "IPO") of common stock and its common stock currently trades on the NASDAQ Exchange under the ticker symbol "CONE". As of December 31, 2018 , all of the issued and outstanding Operating Partnership units of CyrusOne LP are owned, directly or indirectly, by the Company.

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	Summary of Significant Accounting Policies Investment in Real Estate Acquisition of Properties Investment in real estate consist of land, buildings, improvements and integral equipment utilized in our data center operations. We expect most acquisitions to be an acquisition of assets rather than a business combination as our typical acquisitions consist of properties whereby substantially all the fair value of gross assets acquired is concentrated in a single asset set (land, building and in-place leases), which are treated as asset acquisitions. See Business Combinations and Asset Acquisitions herein. Business Combinations and Asset Acquisitions We evaluate whether an acquisition is a business combination or an asset acquisition by determining whether the set of assets is a business. Asset Acquisitions When substantially all of the fair value of gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, the transaction is accounted for as an asset acquisition. Asset acquisitions are recorded at the cumulative acquisition costs and allocated to the assets acquired and liabilities assumed on a relative fair value basis. The Company allocates the purchase price of real estate to identifiable tangible assets such as land, building, land improvements and tenant improvements acquired based on their fair value. In estimating the fair value of each component management considers appraisals, replacement cost, its own analysis of recently acquired and existing comparable properties, market rental data and other related information. Transaction costs associated with asset acquisitions are capitalized. Business Combinations When substantially all of the fair value is not concentrated in a group of similar identifiable assets, the set of assets will generally be considered a business and 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. The following discussion applies to our initial determination of fair value and the resulting subsequent accounting which is generally applicable to both asset acquisitions and business combinations. The fair value of any tangible real estate assets acquired is determined by valuing the building as if it were vacant, and the fair value is then allocated to land, buildings, equipment and improvements. Land values are derived from appraisals, and building and equipment values are calculated as replacement cost less depreciation or estimates of the relative fair value of these assets using net operating income capitalization rates, discounted cash flow analysis or similar methods. We determine in-place lease values based on our evaluation of the specific characteristics of each tenant’s lease agreement and by applying a fair value model. The estimates of fair value of in-place leases include an estimate of carrying costs during the expected lease up periods for the respective leasable area considering current market conditions. In estimating fair value of in-place leases, we consider items such as real estate taxes, insurance, leasing commissions, tenant improvements and other operating expenses to execute similar leases as well as projected rental revenue and carrying costs during the expected lease up period. We amortize the value of in-place leases acquired to expense over the approximate weighted average remaining term of the leases, adjusted for projected tenant turnover, on a composite basis. We determine the value of above-market and below-market in-place leases for acquired properties based on the present value (using an interest rate that reflects the risks associated with the leases acquired) of the difference between (1) the contractual amounts to be paid pursuant to the in-place leases and (2) estimates of current market lease rates for the corresponding in-place leases, measured over a period equal to (i) the remaining non-cancellable lease term for above-market leases, or (ii) the remaining non-cancellable lease term plus any fixed rate renewal options for below-market leases. We record the fair value of above-market and below-market leases as intangible assets or liabilities, and amortize them as an adjustment to revenue over the lease term. We determine the fair value of assumed debt by calculating the net present value of the scheduled debt service payments using current market-based terms for interest rates for debt with similar terms that management believes we could obtain on similar maturities. Any difference between the fair value and stated value of the assumed debt is recorded as a discount or premium and amortized over the remaining life of the loan. Capitalization of Costs We capitalize costs directly related to the development, pre-development or improvement of our investment in real estate, referred to as capital projects and other activities included within this paragraph. Costs associated with our capital projects are capitalized as incurred. If the project is abandoned, these costs are expensed during the period in which the project is abandoned. Costs considered for capitalization include, but are not limited to, construction costs, interest, real estate taxes, insurance, utilities and lease expense, if appropriate. We capitalize indirect costs such as personnel, office and administrative expenses that are directly related to our development projects based on an estimate of the time spent on the construction and development activities. These costs are capitalized only during the period in which activities necessary to ready an asset for its intended use are in progress and such costs are incremental and identifiable to a specific activity to get the asset ready for its intended use. We determine when the capitalization period begins and ends through communication with project and other managers responsible for the tracking and oversight of individual projects. In the event that the activities to ready the asset for its intended use are suspended, the capitalization period will cease until such activities are resumed. In addition, we capitalize initial direct costs incurred for successful origination of new leases. Costs incurred for maintaining and repairing our properties, which do not extend their useful lives, are expensed as incurred. Interest expense is capitalized based on actual qualifying capital expenditures from the period when development commences until the asset is ready for its intended use, at the weighted average borrowing rate during the period. These costs are included in investment in real estate and depreciated over the estimated useful life of the related assets. Impairment Losses When events or circumstances indicate that the carrying amount of a real estate investment may not be recoverable, we review the carrying value of the asset. When such impairment indicators exist, we review an estimate of the undiscounted future cash flows expected to result from the use of the asset and its eventual disposition and compare such amount to its carrying amount. If our undiscounted cash flows indicate that we are unable to recover the carrying value of the real estate investment, an impairment loss is recognized. An impairment loss is measured as the amount by which the real estate investment's carrying value exceeds its estimated fair value. We did not record any impairment losses for the year ended December 31, 2018 and recorded impairment losses of $58.0 million for the year ended December 31, 2017 related to our leased data center facilities in the Connecticut markets and our leased data center facility in Singapore. For the year ended December 31, 2016, we recorded impairment losses of $5.0 million related primarily to two properties, South Bend - Crescent, a leased facility, and Cincinnati - Goldcoast, an owned facility. Cash and Cash Equivalents and Restricted Cash 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 of three months or less. Restricted cash includes cash equivalents held in our name to collateralize standby letters of credit or its use is restricted by contract or regulation. Equity Investment We hold investments in various joint ventures where the Company evaluates its ability to influence the operating or financial decisions of the investee in applying the appropriate method of accounting for such investments. Influence tends to be more effective as the investor's percent of ownership in the voting rights of the investee increases. Our equity investments represent less than 20% of the voting rights of the investees and we do not exercise influence over the operating and financial decisions. Accordingly, we do not account for our equity investments using the equity method accounting. For further information about our equity investments, see Note 9. Equity Investments. Our investment in GDS Holdings Limited (“GDS”) is classified as “available for sale” and is carried at fair value. Effective beginning January 1, 2018, changes in the fair value are reported as a component of net income (loss). Prior to January 1, 2018, such changes in fair value were reported as a component of comprehensive income (loss). See “ Recently Adopted Accounting Pronouncements ” section below. Our other equity investment is carried at cost because we do not exercise influence over the operating and financial decisions of the venture and there is no readily determinable fair value and our investment is recorded at cost less impairment, if any. Dividends paid from operating profits are reported as a component of net income (loss), while other dividends are reported as a return of capital. Goodwill We evaluate goodwill for possible impairment at least annually or upon the occurrence of events or circumstances that indicate that they would more likely than not reduce the fair value of a reporting unit below its carrying amount. For our annual impairment evaluation, we have the option of performing a qualitative or quantitative goodwill impairment analysis. A qualitative analysis, step zero, analyzes the macro-economic environment in which we operate for any significant changes such as deterioration in the market that the Company operates or overall financial performance such as declining cash flows. Also, entity specific changes are analyzed such as change in management, strategy or composition of reporting unit. This assessment of qualitative factors serves as a basis for determining whether it is necessary to perform the step one test. A quantitative analysis, step one, requires the Company to estimate the fair value of the reporting unit and compare the fair value to the carrying value to identify whether the value of the recorded goodwill is impaired. Changes in certain assumptions could have a significant impact on the impairment test for goodwill under step one. The most critical assumptions are projected future growth rates, operating margins, capital expenditures, tax rates, terminal values and discount rates. These assumptions are subject to change as our long-term plans and strategies are updated each year. During the fourth quarters of 2018, 2017 and 2016, we applied step zero and determined that the fair value of the reporting unit is substantially in excess of the carrying amount and therefore determined that incremental goodwill impairment testing was not necessary. Rent and Other Receivables Receivables consist principally of trade receivables from customers with expected credit losses 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. Deferred Revenue and Prepaid Rents Deferred revenue is recorded when a customer makes a contractual payment in excess of revenues recognized in accordance with GAAP. Prepaid rent liability is recorded when a customer makes an advance payment or they are contractually obligated to pay any amounts in advance of the associated lease or service period. Lease Financing Arrangements Lease financing arrangements represent leases of real estate where 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 consolidated balance sheets. These transactions generally do not qualify for sale-leaseback accounting due to our continued involvement in these data center operations. Revenue Recognition Our leasing revenue primarily consists of colocation rent, metered power reimbursements and interconnection revenue. We generally are not entitled to reimbursements for rental expenses including real estate taxes, insurance or other common area operating expenses. The revenues from colocation rent revenue, metered power reimbursements and interconnection are recognized under the lease accounting standard and managed services, equipment sales, installations and other services are recognized under the revenue accounting standard. An allowance for doubtful accounts is recognized when the collection of trade receivables is deemed to be unlikely. Colocation Rent Revenue and Metered Power Reimbursements Revenue Colocation rent revenues are generally billed monthly in advance based on the contracted power or leased space. Some contracts may provide initial free rent periods and rents that escalate over the term of the contract. If rents escalate without the lessee gaining access to or control over additional leased power or space, at the beginning of the lease term, the rental payments 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 power and or leased space, revenue is recognized in proportion to the additional power or space 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 as a straight-line receivable, which is included in other assets in our consolidated balance sheet. When customers make an advance payment in connection with a lease period or contractual obligation, deferred revenue is recorded. 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. The revenue for these types of leases is recorded in colocation lease revenue. Other leases provide that the customer is separately billed for power based upon actual or estimated metered usage. Metered power reimbursement revenue is generally billed one month in arrears, and an estimate of this revenue is accrued in the month that the associated power is provided and recorded in Metered power reimbursements on the Consolidated Statement of Operations. Revenue from Contracts with Customers We adopted the new revenue recognition standard effective January 1, 2018. The information in this section describes our current revenue recognition policies. See Note 4, Recently Adopted Accounting Pronouncements, for additional information related to the adoption. Service Revenue Managed services include the provisioning of a full-service managed data center, monitoring customer computer equipment, managing backups and storage, utilization reporting and other related ancillary information technology services. Management service contracts generally range from one to five years. Other services generally include installation of customer equipment, performing customer system re-boots, server cabinet and cage management, power monitoring, shipping and receiving, resolving technical issues, and other services requested by the customer. Installation services include mounting, wiring, and testing of customer owned equipment. The installation period is typically short term in duration, and accordingly, revenue from the installation of customer equipment is recognized at a point-in-time once the installation is complete and the performance obligation is satisfied. Service revenue is measured based on the consideration specified in the contract and recognized over time as we satisfy the performance obligation. As allowed under GAAP, we have adopted the practical expedient that allows us not to disclose information about remaining performance obligations that have original expected durations of one year or less, the amount of the transaction price allocated to the remaining performance obligations and when we expect to recognize that amount as revenue for the year. We have also adopted the “as invoiced” practical expedient, whereby the Company recognizes revenue in the amount that directly corresponds to the amount of value transferred to the customer. 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. Amortization expense is recognized over the estimated useful lives of finite-lived intangibles. Finite-lived intangibles include trademarks, customer relationships, favorable leasehold interests, in-place leases, trade names and deferred leasing costs. See Note 10, Goodwill, Intangible and Other Long-Lived Assets, for details. Foreign Currency Translation and Transactions Gains or losses from translation of foreign operations where the local currency is the functional currency are included as components of other comprehensive income (loss). 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 exchange rates during the period. Gains or losses from foreign currency transactions are included in determining net income (loss). Stock-Based Compensation We have a stock-based incentive award plan for our employees and directors. Stock-based compensation expense associated with these awards is recognized in general and administrative expenses, property operating expenses and sales and marketing in our consolidated statements of operations. We measure stock-based compensation at the estimated fair value on the grant date and recognize the amortization of stock-based compensation expense over the requisite service period. Fair value is determined based on assumptions related to volatility, interest rates and our market and company performance. Fair Value Measurements Fair value measurements are utilized in accounting for business combinations, asset acquisitions, testing of goodwill and other long-lived assets for impairment, recording unrealized gain/loss on available-for-sale securities 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. Segment Information Our data centers have similar revenues and operating expenses across all geographic locations. The service offerings and delivery of services are provided in a similar manner, using the same types of facilities and similar technologies. Our chief operating decision maker, the Company's Chief Executive Officer, reviews our financial information on an aggregate basis and as a result, we have one reportable business segment. One customer represented approximately 18% of our revenue for the years ended December 31, 2018 and 2017 . Revenues from properties were $821.4 million , $672.0 million and $529.1 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. We had net investment in real estate of $4.3 billion and $3.1 billion , at December 31, 2018 and 2017 , respectively. Use of Estimates Preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the 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. Significant estimates include and are related to determining lease terms and revenue recognition, the fair value for purchase price allocations for business combinations and asset acquisitions, and the useful lives of real estate and other long-lived assets. Actual results may differ from these estimates and assumptions. Reclassifications Certain financial information has been revised to conform to the current year presentation due to changes in the significance of the particular activity. The following items have been reclassified: Balance Sheet as of December 31, 2017 • Land related to construction in progress ( $8.7 million ) and land held for future development ( $63.8 million ) were previously included in investment in real estate - land ( $72.5 million ). • Notes receivable and long-term installment contracts are classified within other assets. These items were previously included in rent and other receivables ( $3.3 million ). • Construction costs payable are classified in a separate liability and were previously included in accounts payable and accrued expenses ( $115.5 million ). • Dividends payable are classified in a separate liability and were previously included in accounts payable and accrued expenses ( $41.8 million ). • Lease finance arrangements are classified in capital lease obligations and lease financing arrangements. These items were previously included in a separate line for lease finance arrangements ( $131.9 million ). • Equity investment is classified in a separate asset account and was previously included in other assets ( $175.6 million ). Statement of Cash Flows for the year ended December 31, 2017 • The cash flow effect of the change in interest accrual is classified within accounts payable and accrued expenses. These items were previously combined with non-cash interest expense, net in the comparable prior year period ( $12.3 million ). • Debt issuance and debt extinguishment costs are classified within proceeds from debt, net. These items were previously included in separate lines, debt issuance costs ( $19.0 million ) and payment of debt extinguishment costs ( $30.4 million ), in the comparable prior year period. Statement of Cash Flows for the year ended December 31, 2016 • The cash flow effect of the change in interest accrual is classified within accounts payable and accrued expenses. These items were previously combined with non-cash interest expense, net in the comparable prior year period ( $1.3 million ). • Debt issuance costs are classified within proceeds from debt, net. This item was previously included in a separate line, debt issuance costs ( $8.7 million ) in the comparable prior year period. • The note payment is classified within payments on debt. This item was previously included in a separate line, payment of note payable ( $8.7 million ) in the comparable prior year period.

Recently Issued Accounting Stan

Recently Issued Accounting Standards	12 Months Ended
	Dec. 31, 2018
Accounting Changes and Error Corrections [Abstract]
Recently Issued Accounting Standards	Recently Issued Accounting Standards Recently Adopted Accounting Pronouncements On January 1, 2018, we adopted the Financial Accounting Standards Board ("FASB") pronouncement Accounting Standards Update ("ASU") 2014-09 with respect to revenue recognition. The revised guidance outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and superseded prior revenue recognition guidance, including industry-specific revenue guidance. The revised guidance replaced most existing revenue and real estate sale recognition guidance in GAAP. The standard specifically excludes lease contracts, which is our primary recurring revenue source; however, our revenue accounting for managed services and sales of real estate and equipment will follow the revised guidance. We adopted the new standard using the modified retrospective transition method, where financial statement presentations prior to the date of adoption are not adjusted. Transactions that were not closed as of the adoption date were adjusted to reflect the new standard and we recorded an adjustment to beginning retained earnings of $0.3 million . See Note 5 "Revenue Recognition" for further information regarding the adoption of the new accounting standard, including expanded quantitative and qualitative disclosures regarding revenue recognition. On January 1, 2018, we adopted ASU 2017-05, which requires the derecognition of a business in accordance with Accounting Standards Codification ("ASC") 810, Consolidations, including instances in which the business is considered in substance real estate. In cases where a controlling interest in real estate was sold but a noncontrolling interest is retained, we may record a gain or loss related to both the sold and retained interests. The adoption of this standard did not have an impact on our condensed consolidated financial statements, but depending on future transactions, may in the future. On January 1, 2018, we adopted ASU 2016-01 related to equity investments. Equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) are to be measured at fair value with changes in fair value now recognized in net income. Previously changes in fair value for available for sale equity investments were recorded in other comprehensive income (loss). The adoption of the new standard was made through a cumulative-effect adjustment to beginning retained earnings of $75.6 million . Prior financial statement amounts were not adjusted. For the year ended December 31, 2018 , the unrealized gain on investment was $9.9 million . New Accounting Pronouncements In August 2018, the Securities and Exchange Commission ("SEC") issued Securities Act Release No. 33-10532, Disclosure Update and Simplification, which amends certain of its disclosure requirements and is intended to facilitate the disclosure of information to investors and simplify compliance without significantly altering the total mix of information provided to investors. The amendments became effective on November 5, 2018. Among the amendments is the requirement to present the changes in shareholders’ equity in the interim financial statements (either in a separate statement or footnote) in quarterly reports on Form 10-Q. Based on the effective date of the amendments and Exchange Act Forms Compliance and Disclosure Interpretation Question 105.09 issued by the staff of the SEC’s Division of Corporation Finance on September 25, 2018 and updated on October 4, 2018, the Company’s first presentation of changes in shareholders’ equity will be in its Form 10-Q for the quarter ending March 31, 2019. In August 2018, the FASB issued ASU 2018-15, which clarifies the accounting for implementation costs incurred in a hosting arrangement that is a service contract. Capitalization of these implementation costs are accounted for under the same guidance as implementation costs incurred to develop or obtain internal-use software and recorded as a prepaid asset. These capitalized costs are to be expensed ratably over the hosting arrangement term as operating expense, along with the service fees. The guidance is effective for periods beginning after December 15, 2019. Early adoption is allowed. The Company does not plan to early adopt this guidance and is evaluating the impact of the new standard. In August 2018, the FASB issued ASU 2018-13, which changes the fair value measurement disclosure requirements of ASC 820. Under this ASU, key provisions include new, eliminated and modified disclosure requirements. The guidance is effective for periods beginning after December 15, 2019. Early adoption is allowed. The Company does not plan to early adopt this guidance and is evaluating the impact of the new standard. In June 2018, the FASB issued ASU 2018-07, which simplifies the accounting for share-based payments granted to nonemployees for goods and services. Under this ASU, most of the guidance on such payments to nonemployees would be aligned with the requirements for share-based payments granted to employees. The Company accounts for its share-based payments to our board of director members in the same manner as employees. Other than to our board of director members, the Company does not award share-based payments to any other nonemployees. Therefore, we do not expect this accounting pronouncement to significantly impact our financial statements. The guidance is effective for periods beginning after December 15, 2018. Early adoption is allowed. In February 2016, the FASB issued ASU 2016-02, regarding the accounting for leases for both lessees and lessors. In July 2018, ASU 2016-02 was amended, providing another transition method by allowing companies to initially apply the new lease standard in the year of adoption and not the earliest comparative period. The lease standard amendment also provided a practical expedient for an accounting policy election for lessors, by class of underlying asset, to not separate nonlease components from the associated lease components as long as the timing and pattern of transfer are the same for the nonlease and lease components. Lessees will recognize a right-of-use asset and a lease liability for 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 adjusted for any initial direct costs of the lease, lease incentives or early lease payments. For income statement purposes, the FASB retained a dual classification model, requiring lessees to classify leases as either operating or finance. Operating leases will result in straight-line rent expense (similar to current operating leases) while finance leases will result in interest and amortization expense (similar to current capital leases). Classification will be based on criteria that are largely similar to those applied in current lease accounting. The new standard may be adopted using a modified retrospective transition and provides for certain practical expedients. We are evaluating the impact of ASU 2016-02 on our consolidated financial statements, where we believe the primary impact as a lessee will relate to leases in which we are deemed to be the accounting owner due to our involvement in the construction of the assets. Previously, under the old standard, these assets were capitalized as investments in real estate and a related financing obligation was recorded. Under the new standard, these assets and liabilities will be removed from the Company’s balance sheet and we will record a right-of-use asset and a corresponding lease liability. Additionally, under the new standard, a right-of-use asset and corresponding lease liability will be recorded for leases currently treated as operating leases. The accounting for lessors will remain largely unchanged from current GAAP; however, the new lease standard requires that lessors expense, on an as-incurred basis, certain initial direct costs that are not incremental in negotiating a lease. Under existing standards, these costs are capitalizable and therefore the new lease standard will result in certain of these costs being expensed as incurred after adoption. During the twelve months ended December 31, 2018 and 2017, we capitalized $1.7 million and $0.9 million , respectively, of internal costs related to our leasing activities. Further under current lessor accounting, a real estate lease could only be a sales-type lease if ownership of the real estate was transferred to the lessee. With the adoption of ASU 2016-02, there will no longer be an exclusion for real estate leases, where the same classification guidance applies to all leases. If, as lessor, our real estate leases would be classified as sales-type leases, the real estate asset would be eliminated, a net investment asset would be recognized generally equal to the present value of the minimum lease payments plus the unguaranteed residual value and a selling profit or loss. We are required to adopt ASU 2016-02 January 1, 2019, and plan to use the modified retrospective approach. In January 2018, the FASB issued ASU 2018-01, which permits an entity to elect a practical expedient to not evaluate land easements that were not previously accounted for as leases prior to the entity’s adoption of the new lease accounting standard. Once the new lease standard is adopted, it should be applied prospectively to all new or modified land easements. The Company expects to adopt this new guidance effective January 1, 2019, along with the new lease standard, and will continue to evaluate the impact of this new guidance until it becomes effective. In June 2016, the FASB issued ASU 2016-13 providing guidance which requires certain financial assets to be presented at the net amount expected to be collected. The guidance affects entities holding financial assets and net investment in leases that are not accounted for at fair value through net income. The guidance will apply to our trade receivables, notes receivable, net investments in leases and any other future financial assets that have the contractual right to receive cash that we may acquire in the future. The guidance is effective for periods beginning for us January 1, 2020. Early adoption is permitted. We are currently evaluating the impact of the new standard.

Revenue Recognition

Revenue Recognition	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue Recognition	Revenue Recognition We have consistently applied our revenue accounting policies to all periods presented in these consolidated financial statements except for customer equipment installation services. Beginning with our adoption of revenue recognition in ASU 2014-09 on January 1, 2018 (see Note 3, Summary of Significant Accounting Policies, and Note 4, Recently Issued Accounting Standards), revenue from the installation of customer equipment is recognized at a point-in-time. The asset being enhanced or installed belongs to the customer, and the benefits of the installation service are being consumed at the completion of the service. Prior to the adoption of the new revenue recognition standard, the revenue from these transactions was deferred over the contract term. The deferred revenue liability balance related to completed installations, less any associated deferred costs, as of the date of adoption, calculated on a cumulative modified retrospective basis was $0.3 million and has been included in the cumulative effective adjustment to opening retained earnings. Disaggregation of Revenue For the year ended December 31, 2018 , revenue disaggregated by primary revenue stream is as follows (in millions). Year Ended December 31, 2018 Year Ended December 31, 2017 Colocation rent $ 644.6 $ 539.8 Metered power 104.0 70.2 Interconnection revenue 40.0 34.1 Equipment sales 11.9 7.3 Other revenue 20.9 20.6 Revenue $ 821.4 $ 672.0 Total revenue from contracts with customers was $34.1 million and $29.1 million for the year ended December 31, 2018 and 2017, respectively. Lease revenue was $787.3 million and $642.9 million for the year ended December 31, 2018 and 2017, respectively. Total other revenues from customers generated from operations outside of the United States were insignificant for the year ended December 31, 2018 . For further information see Recently Adopted Accounting Pronouncements, ASU 2014-09.

Acquisitions and Purchase of Fi

Acquisitions and Purchase of Fixed Assets	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Acquisitions and Purchase of Fixed Assets	Acquisitions and Purchases of Fixed Assets Acquisitions of Data Centers On August 24, 2018, the Company completed its previously announced acquisition of Zenium Topco Ltd. and certain other affiliated entities ("Zenium"). Zenium is a hyperscale data center provider in Europe with four operating data centers in London and Frankfurt, and land sites available for development in London and Frankfurt. In connection with the acquisition, and after giving effect to a post-closing working capital adjustment, the Company paid aggregate cash consideration of approximately $462.8 million , net of approximately $12.7 million of cash acquired, and assumed outstanding indebtedness of approximately $86.3 million . In the fourth quarter of 2018, the Company paid approximately $1.0 million related to the post-closing working capital adjustment which is included above in the aggregate cash consideration. The Company financed the acquisition with proceeds from the $300.0 million delayed draw term loan included in the 2023 Term Loan and $174.5 million of borrowings under the $1.7 Billion Revolving Credit Facility (each as defined below). As a result of the acquisition, the Company recognized a $72.7 million deferred tax liability associated with temporary differences between the book basis of the assets acquired in the transaction. The Company evaluated the acquisition and determined that substantially all of the fair value of the gross assets was concentrated in a group of similar identifiable assets and accounted for the transaction as an acquisition of assets. The consolidated financial statements of CyrusOne Inc. include the operating results of Zenium since the acquisition date, which was August 24, 2018. The following table summarizes the estimated fair values of all assets acquired at the date of acquisition: IN MILLIONS Investment in real estate $ 597.3 Cash and cash equivalents 12.7 Rent and other receivables 9.0 Intangible assets: Trade name 1.8 Leasehold interest 1.7 In-place leases 61.5 Other assets 1.1 Accounts payable (22.3 ) Deferred revenue (3.3 ) Capital lease obligations (25.0 ) Deferred tax liability (72.7 ) Debt (86.3 ) Net assets acquired attributable to CyrusOne Inc. 475.5 Cash acquired (12.7 ) Net cash paid at acquisition $ 462.8 On February 28, 2017 , the Company acquired two data centers located in Raleigh-Durham, North Carolina and Somerset, New Jersey (the "Sentinel Properties") which was accounted for as an asset acquisition. The Company's aggregate cash consideration paid totaled approximately $492.3 million , including related acquisition and closing costs. The two properties consist of approximately 160,000 colocation square feet and approximately 21 megawatts of power capacity. The following table summarizes the estimated fair values of all assets acquired at the date of acquisition: IN MILLIONS 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 Accounts payable (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 Land for future development During the years ended December 31, 2018 and 2017 , the Company purchased approximately 182 acres of land for $182.3 million , and 209 acres of land for $35.3 million , respectively. Real Estate Investments and Intangibles and Related Depreciation and Amortization As of December 31, 2018 and 2017, major components of our real estate investments and intangibles and related accumulated depreciation and amortization are as follows (in millions): December 31, 2018 December 31, 2017 Investment in Real Estate Intangibles Investment in Real Estate Intangibles Buildings and Improvements Equipment Customer Relationships In Place Leases Other Contractual Buildings and Improvements Equipment Customer Relationships In Place Leases Other Contractual Cost $ 1,677.5 $ 2,630.2 $ 247.1 $ 136.0 19.5 $ 1,371.4 $ 1,813.9 $ 247.1 $ 75.9 $ 16.1 Less: accumulated depreciation and amortization (481.8 ) (572.7 ) (137.9 ) (21.1 ) (7.9 ) (418.2 ) (364.2 ) (123.0 ) (7.1 ) (6.0 ) Net $ 1,195.7 $ 2,057.5 $ 109.2 $ 114.9 $ 11.6 $ 953.2 $ 1,449.7 $ 124.1 $ 68.8 $ 10.1

Investment in Real Estate

Investment in Real Estate	12 Months Ended
	Dec. 31, 2018
Real Estate [Abstract]
Investment in Real Estate	Investment in Real Estate A schedule of our gross investment in real estate follows: IN MILLIONS As of December 31, 2018 2017 Land Building and Equipment Land Building and Equipment Dallas - Carrollton $ 16.1 $ 62.2 $ 272.5 $ 16.1 $ 61.8 $ 210.7 Houston - Houston West I 1.4 85.2 51.1 1.4 85.2 49.8 Northern Virginia - Sterling II — 28.8 112.4 — 28.8 112.3 San Antonio III — 40.2 99.0 — 40.3 96.8 Cincinnati - 7th Street 0.9 114.1 37.4 0.9 110.6 33.1 Northern Virginia - Sterling V 14.5 80.8 295.8 14.5 35.7 108.8 Somerset I 12.1 125.8 91.0 9.3 124.8 83.7 Dallas - Lewisville — 76.8 39.6 — 76.7 37.4 Totowa - Madison — 28.5 57.7 — 28.5 55.1 Chicago - Aurora I 2.4 32.4 132.9 2.4 32.4 125.0 Cincinnati - North Cincinnati 0.9 77.9 12.4 0.9 77.4 9.9 Phoenix - Chandler II — 16.2 39.4 — 16.2 38.9 Wappingers Falls I — 11.3 22.0 — 11.3 18.0 San Antonio I 4.6 31.7 35.3 4.6 31.7 34.8 Houston - Houston West II 2.7 22.9 50.9 2.7 22.8 50.1 Phoenix - Chandler I 10.5 58.3 68.7 10.5 58.2 65.9 Phoenix - Chandler III — 11.4 50.8 — 11.4 50.0 Northern Virginia - Sterling I 6.9 20.2 60.4 7.0 20.0 59.4 Raleigh-Durham I 2.1 79.8 75.4 2.1 78.0 76.0 Houston - Galleria — 71.0 20.2 — 68.6 17.6 Phoenix - Chandler VI 2.4 23.3 100.3 2.4 15.7 49.2 Northern Virginia - Sterling III — 22.2 61.3 — 22.2 61.3 Frankfurt I 11.2 125.5 178.8 — — — Austin II 2.0 23.4 8.7 2.0 23.4 7.2 San Antonio II 7.0 30.3 60.8 7.0 29.0 60.4 Florence 2.2 42.0 8.4 2.2 42.0 5.3 Austin III 3.3 11.7 47.0 3.3 10.6 33.9 Phoenix - Chandler IV — 18.4 43.3 — 18.3 40.9 San Antonio IV — 42.1 48.2 — — 17.9 Cincinnati - Hamilton — 43.7 7.9 — 50.2 6.0 Northern Virginia - Sterling IV 4.6 20.0 76.0 4.6 20.0 73.7 Phoenix - Chandler V — 10.7 53.4 — 5.9 20.5 London II — 25.2 74.8 — — — London I — 34.1 26.3 — — — London - Great Bridgewater — 26.8 1.2 — 28.4 1.1 Cincinnati - Mason — 20.3 1.7 — 20.3 1.6 Stamford - Riverbend — 2.9 7.8 — 2.9 6.9 Houston - Houston West III 7.2 18.0 31.4 7.2 17.9 30.7 Norwalk I* — 13.6 10.1 — 13.5 9.4 Chicago - Lombard 0.7 4.7 8.1 0.7 4.7 7.7 Stamford - Omega* — 2.6 0.7 — 2.6 0.7 Cincinnati - Blue Ash — 0.7 0.2 — 0.7 0.2 Totowa - Commerce — 4.1 1.7 — 4.1 1.6 South Bend - Crescent — 1.7 0.2 — 1.7 0.1 IN MILLIONS As of December 31, 2018 2017 Land Building and Equipment Land Building and Equipment South Bend - Monroe — 2.5 0.4 — 2.5 0.3 Chicago - Aurora II 2.6 22.6 68.6 2.6 8.3 42.9 Chicago - Aurora Tower — 4.9 0.4 — — — Dallas - Midway — — — — 2.0 0.4 Dallas - Marsh — — — — 0.1 0.6 Cincinnati - Goldcoast 0.2 4.0 0.1 0.2 4.0 0.1 Northern Virginia - Sterling VI — — 77.5 — — — Total $ 118.5 $ 1,677.5 $ 2,630.2 $ 104.6 $ 1,371.4 $ 1,813.9 Land held for future development $ 176.4 $ — $ — $ 63.8 $ — $ — As of December 31, 2018 and December 31, 2017 , construction in progress includes $69.1 million and $8.7 million of land which is under active development, respectively. In addition, construction in progress was $744.9 million and $487.1 million as of December 31, 2018 and December 31, 2017 , respectively, as we continue to build data center facilities. For the year ended December 31, 2018 , our capital expenditures were $1,328.5 million , as shown on the statement of cash flows. This included the purchase price of the properties acquired in the Zenium acquisition on August 24, 2018 for $462.8 million and $865.7 million for other developments primarily in Chicago, Cincinnati, Dallas, Northern Virginia, Phoenix and San Antonio; and the purchase of parcels of land in Phoenix, Northern Virginia, Allen, Amsterdam, Santa Clara and Frankfurt for future development. For the year ended December 31, 2017, our capital expenditures were $1,406.8 million , as shown on the statement of cash flows. This included the purchase price of the Sentinel Properties on February 28, 2017 for $492.3 million and $914.5 million for other developments primarily in Chicago, Cincinnati, Dallas, Northern Virginia, Phoenix and San Antonio; and the purchase of parcels of land in Allen, Texas, Atlanta, Georgia and Quincy, Washington for future development. No impairment charges were recognized during the year ended December 31, 2018 . For the year ended December 31, 2017, we recognized impairment losses of $58.0 million which includes the impairment loss of $54.4 million as mentioned below and an impairment of $3.6 million related to our leased facility in Singapore. During the year ended December 31, 2017, we incurred an impairment loss of $54.4 million for our Norwalk I, Stamford - Riverbend and Stamford - Omega facilities, which are in the Connecticut market and were acquired as part of the acquisition of Cervalis, a privately-held owner and operator of data centers, in July 2015. These are leased facilities and Cervalis was deemed to be the accounting owner of the buildings, excluding land, due to their involvement in the construction of structural improvements to these facilities and continuing involvement once construction was completed. Upon acquisition of Cervalis, all assets acquired and liabilities assumed were recorded at their estimated fair values. For new leases, our sales cycle is typically up to two years, and our revenue and profit expectations were revised as compared to the assumptions contained at the time of the acquisition. Due to lack of demand we have experienced for data centers in the Connecticut market, we revised our expectations for operations of these facilities through the end of their lease terms. The amount of impairment recognized was the excess of the carrying value over the fair value of the assets. Fair value was determined by the discounted cash flow method based on management's best estimates of a market participant using available information.

Notes Receivable

Notes Receivable	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Notes Receivable	Notes Receivable The carrying amount of notes receivable was $2.1 million and $3.3 million as of December 31, 2018 and 2017 , respectively, and consisted of the following: IN MILLIONS For the year ended December 31, 2018 2017 Note 1 $ 1.4 $ 1.8 Note 2 0.3 0.6 Note 3 — 0.5 Note 4 0.3 0.4 Note 5 0.1 — Total $ 2.1 $ 3.3 Each of the above notes is from a different customer. Note 1 matures in September 2021 , and the payments are approximately $50,000 per month. Note 2 matures in November 2019 , and the payments are approximately $26,000 per month. Note 3 matured in February 2018, and the payments were approximately $30,000 per month. Note 4 matures in October 2020 , and the payments are approximately $12,000 per month. Note 5 matures in June 2021 , and the payments are approximately $4,000 per month. These notes are included in rent and other receivables on the consolidated balance sheets.

Equity Investment

Equity Investment	12 Months Ended
	Dec. 31, 2018
Investments, Debt and Equity Securities [Abstract]
Equity Investment	Equity Investments The Company has an equity investment, accounted for using the fair value method in GDS, a developer and operator of high-performance, large-scale data centers in China. On October 18, 2017, the Company purchased newly issued unregistered ordinary shares equivalent to 8.0 million American depository shares (ADS) at a price per Class A ordinary share equivalent to $12.45 per ADS, a 4% discount to the October 17, 2017 closing price, for a total investment of $100 million . Each ADS is equivalent to eight ordinary shares. As of December 31, 2018 the ADS Class A ordinary share equivalent was $23.09 per ADS for a total fair value of $185.5 million . For the year ended December 31, 2018 , the unrealized gain on investment of 9.9 million was recognized in the Consolidated Statement of Operations in Unrealized gain on marketable equity investment. For further information see Recently Adopted Accounting Pronouncements, adoption of ASU 2016-01. On October 8, 2018, the Company made an $11.9 million investment in exchange for a 10% equity interest in ODATA Brasil S.A. and ODATA Colombia S.A.S. (collectively "ODATA"). ODATA, a Brazilian headquartered company, specializes in providing colocation services to wholesale customers, such as hyperscale cloud providers, financial services and telecommunications companies, and also to enterprises across multiple industries. On October 30, 2018, the Company made an additional $0.7 million investment in ODATA Colombia S.A.S. In connection with these investments, CyrusOne and ODATA entered a commercial agreement covering leasing activity with CyrusOne customers in the ODATA portfolio. In addition, our Chief Technology Officer joined the ODATA board of directors in October 2018. In evaluating the appropriate accounting method for its investment in ODATA, the Company considered its right to appoint a director to the ODATA board of directors, as well as other relevant factors, in evaluating the Company’s ability to exercise significant influence over the operating and financial policies of ODATA as provided in ASC 323-10-15-6 and concluded that the investment should be accounted for under the cost method.

Goodwill, Intangible and Other

Goodwill, Intangible and Other Long-Lived Assets	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill, Intangible and Other Long-Lived Assets	Goodwill, Intangible and Other Long-Lived Assets The carrying amount of goodwill was $455.1 million as of December 31, 2018 and 2017 . See Note 6 for the explanation of changes to intangible assets. Summarized below are the carrying values for the major classes of intangible assets: IN MILLIONS For the year ended December 31, 2018 2017 Weighted- Gross Carrying Amount Accumulated Amortization Total Gross Carrying Amount Accumulated Amortization Total Customer relationships 11 $ 247.1 $ (137.9 ) $ 109.2 $ 247.1 $ (123.0 ) $ 124.1 Trademark/tradename 6 11.5 (6.7 ) 4.8 9.7 (5.3 ) 4.4 Favorable leasehold interest 36 5.7 (0.7 ) 5.0 4.1 (0.5 ) 3.6 In place customer leases 6 136.0 (21.1 ) 114.9 75.9 (7.1 ) 68.8 Above and below market leases 7 2.3 (0.5 ) 1.8 2.3 (0.2 ) 2.1 Total $ 402.6 $ (166.9 ) $ 235.7 $ 339.1 $ (136.1 ) $ 203.0 There were no goodwill or intangible asset impairments for the years ended December 31, 2018 or 2017 . Amortization expense for acquired intangible assets was $30.6 million , $25.1 million and $20.1 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. The following table presents estimated amortization expense for each of the next five years and thereafter, commencing January 1, 2019 : IN MILLIONS Total 2019 $ 40.2 2020 39.0 2021 31.8 2022 28.5 2023 20.7 Thereafter 75.5 Total $ 235.7

Other Assets

Other Assets	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Other Assets	Other Assets As of December 31, 2018 and 2017 , the components of other assets are as follows (in millions): December 31, 2018 December 31, 2017 Straight line receivables, net $ 128.7 $ 100.0 Deferred leasing and other contract costs 43.6 33.7 Prepaid expenses 26.4 20.0 Non-real estate assets, net 18.4 16.7 Other 22.9 10.5 Total $ 240.0 $ 180.9 Non-real estate assets primarily include administrative related equipment and office leasehold improvements, depreciated or amortized over the shorter of the assets useful life or the related lease term.

Capital Lease Obligations and L

Capital Lease Obligations and Lease Financing Arrangements	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Capital Lease Obligations and Lease Financing Arrangements	Capital Lease Obligations and Lease Financing Arrangements As of December 31, 2018 and 2017 , capital lease obligations and lease financing arrangements are as follows (in millions): December 31, 2018 December 31, 2017 Capital lease obligations $ 33.4 $ 10.1 Lease financing arrangements 123.3 131.9 Total $ 156.7 $ 142.0 Capital lease obligations —We use leasing as a source of financing for certain data center facilities and related equipment. We currently operate five data center facilities subject to capital leases. The remaining terms of our capital leases range from 2021 to 2041. 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 the accounting owner and were involved in the construction of structural improvements to develop or improve buildings into data centers. The remaining terms of our lease financing arrangements range from 2020 to 2035. The following table summarizes aggregate minimum principal payments of the capital lease obligations for the five years subsequent to December 31, 2018 , and thereafter (in millions): Capital Leases 2019 $ 2.7 2020 2.8 2021 2.9 2022 2.0 2023 1.0 Thereafter 22.0 Total $ 33.4 Interest expense on capital lease obligations and lease financing arrangements was $9.0 million , $9.0 million and $10.6 million for the years ended December 31, 2018 , 2017 and 2016 respectively. The following table summarizes aggregate maturities of total future value and present value of the minimum payments associated with our lease financing arrangements for the five years subsequent to December 31, 2018 , and thereafter: IN MILLIONS Future Value of Payments Interest Present Value of Payments 2019 $ 15.0 $ 7.3 $ 7.7 2020 27.6 6.6 21.0 2021 11.4 5.7 5.7 2022 11.6 5.4 6.2 2023 10.0 4.1 5.9 Thereafter 89.1 12.3 76.8 Total lease financing arrangements $ 164.7 $ 41.4 $ 123.3 The payment of interest on capital leases over the next five years and thereafter will be $1.7 million , $1.5 million , $1.3 million , $1.1 million , $0.9 million and $9.3 million , respectively.

Debt

Debt	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Debt	Debt As of December 31, 2018 and 2017 , the components of debt are as follows (unless otherwise noted, interest rate and maturity date information are as of December 31, 2018 ) (in millions): December 31, 2018 December 31, 2017 Interest Rate (a) Maturity Date $3.0 Billion Credit Facility: $1.7 Billion Revolving Credit Facility $ 143.0 $ — Monthly EURIBOR + 1.45% March 2022 (b) 2023 Term Loan 1,000.0 — Monthly LIBOR + 1.40% March 2023 2025 Term Loan 300.0 — Monthly LIBOR + 1.70% March 2025 $2.0 Billion Credit Facility: $1.1 Billion Revolving Credit Facility — — Monthly LIBOR + 1.55% N/A 2021 Term Loan — 250.0 Monthly LIBOR + 1.50% N/A 2022 Term Loan — 650.0 Monthly LIBOR + 1.50% N/A 2024 Notes, including bond premium of $5.5 million 705.5 706.8 5.000 % March 2024 2027 Notes, including bond premium of $9.1 million 509.1 510.5 5.375 % March 2027 Deferred financing costs (32.9 ) (27.9 ) — — Total $ 2,624.7 $ 2,089.4 (a) - Monthly LIBOR at December 31, 2018 was 2.53% . (b) - The Company may exercise a one -year extension option, subject to certain conditions. On March 29, 2018, the Company entered into a new $3.0 billion unsecured credit facility. The new credit facility consists of a $1.7 billion revolving credit facility (" $1.7 Billion Revolving Credit Facility"), which includes a $750.0 million multicurrency borrowing sublimit, a 5 -year term loan with commitments totaling $1.0 billion ("2023 Term Loan") and a $300.0 million 7 -year term loan ("2025 Term Loan") (collectively, the " $3.0 Billion Credit Facility"). We borrowed $700.0 million under the 2023 Term Loan on March 31, 2018, and the 2023 Term Loan includes a delayed draw feature which allowed the Company to draw $300.0 million in up to three tranches over a six -month period in multiple currencies. The Company exercised the draw as a part of the Zenium acquisition. The $1.7 Billion Revolving Credit Facility has the option to borrow in non-USD currencies and includes a one -year option which, if exercised by the Company, would extend the final maturity to March 2023. The $3.0 Billion Credit Facility also includes an accordion feature providing for an aggregate increase in the revolving and term components to $4.0 billion , subject to certain conditions. The $1.7 Billion Revolving Credit Facility, and the 2023 and 2025 Term Loans, are prepayable at our option. On March 29, 2018, borrowings of $1.0 billion under the $3.0 Billion Credit Facility were used to fully retire a previous $2.0 billion credit facility. The previous $2.0 billion credit facility consisted of a $1.1 billion senior unsecured revolving credit facility (" $1.1 Billion Revolving Credit Facility"), a $250 million 5 -year term ("2021 Term Loan") and a $650 million 7 -year term loan ("2022 Term Loan") (collectively, the " $2.0 Billion Credit Facility"). The aggregate outstanding principal balance of the $2.0 Billion Credit Facility at the date of the prepayment was $900.0 million and we recognized a loss on early extinguishment of debt of $3.1 million . In August 2018, the Company financed the acquisition of Zenium with proceeds from its $300.0 million delayed draw term loan included in the 2023 Term Loan and $174.5 million of borrowings under the $1.7 Billion Revolving Credit Facility. In connection with the acquisition, the Company assumed a six -year, €100.0 million construction facility, which was paid off in December 2018. We pay commitment fees for the unused amount of borrowings on the $1.7 Billion Revolving Credit Facility and 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. The commitment fees decrease to 0.15% per annum upon 50% or greater utilization. We also paid commitment fees on the $1.1 Billion Revolving Credit Facility through its retirement in March 2018. Commitment fees were $3.8 million , $1.9 million and $1.6 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. As of December 31, 2018 , additional borrowing capacity under the $1.7 Billion Revolving Credit Facility was approximately $1,549.0 million . As of December 31, 2018 , we had $8.0 million of outstanding letters of credit issued under our credit facilities. On March 17, 2017, the Operating Partnership and CyrusOne Finance Corp., a single-purpose finance subsidiary, both wholly-owned subsidiaries of the Company (together, the "Note Issuers") completed an offering of $500.0 million aggregate principal amount of 5.000% senior notes due 2024 ("Original 2024 Notes") and $300.0 million aggregate principal amount of 5.375% senior notes due 2027 ("Original 2027 Notes") in a private offering. The Company received proceeds of $791.2 million , net of underwriting costs and other deferred financing costs related to the notes. On November 3, 2017, the Note Issuers completed an offering of $200.0 million aggregate principal amount of 5.000% senior notes due 2024 ("Additional 2024 Notes") and $200.0 million aggregate principal amount of 5.375% senior notes due 2027 ("Additional 2027 Notes") in a private offering. The Additional 2024 Notes have terms substantially identical to the Original 2024 Notes and the Additional 2027 Notes have terms substantially identical to the Original 2027 Notes. The Original 2024 Notes and the Additional 2024 Notes form a single class of securities ("2024 Notes"), and the Original 2027 Notes and the Additional 2027 Notes form a single class of securities ("2027 Notes"). The Company received proceeds of $416.1 million , net of underwriting costs of $4.4 million . The Original 2024 Notes and the Additional 2024 Notes are referred to as the 2024 Notes and the Original 2027 Notes and the Additional 2027 Notes are referred to as the 2027 Notes. On January 8, 2018, the Issuers completed an exchange offer with respect to the 2024 Notes and the 2027 Notes and all validly tendered 2024 Notes and 2027 Notes were exchanged for notes registered with the SEC. The 2024 Notes and 2027 Notes are senior unsecured obligations of the Note Issuers, which rank equally in right of payment with all existing and future unsecured senior indebtedness of the Note Issuers. The 2024 Notes and 2027 Notes are effectively subordinated in right of payment to any secured indebtedness of the Note Issuers to the extent of the value of the assets securing such indebtedness. The senior notes are guaranteed on a joint and several basis by the Company, the General Partner and all of CyrusOne LP’s existing domestic subsidiaries that guarantee the $3.0 Billion Credit Facility. 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 senior notes in the future. Each such guarantee is 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 2024 Notes and 2027 Notes are structurally subordinated to all liabilities (including trade payables) of each subsidiary of CyrusOne LP that does not guarantee the 2024 Notes and 2027 Notes. The 2024 Notes and 2027 Notes may be redeemed at our option prior to their scheduled maturity dates at the prices and premiums and on the terms set forth in the respective indentures governing the notes. On November 20, 2012, wholly-owned subsidiaries of the Company issued $525.0 million of 6.375% senior notes due 2022 (the "6.375% Notes"). In March 2017, the Company repurchased all of the 6.375% Notes with an aggregate face value of $474.8 million , a net carrying value of $469.0 million , for total consideration of $515.1 million , including accrued and unpaid interest of $10.3 million . In connection with the debt prepayment, we recognized a loss on early extinguishment of debt of $36.2 million . Our debt agreements contain customary provisions with respect to events of default, affirmative and negative covenants and borrowing conditions. The most restrictive covenants are generally included in the $3.0 Billion Credit Agreement. The $3.0 Billion 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. In order to continue to have access to amounts available under the $3.0 Billion Credit Agreement, the Company must remain in compliance with all of that agreement's covenants. As of December 31, 2018 , we believe we are in compliance with all provisions of our debt agreements. As of December 31, 2018 , all of our outstanding debt matures between 2023 and 2027. The following table summarizes aggregate maturities of the $3.0 Billion Credit Facility and 2024 Notes and 2027 Notes for the five years subsequent to December 31, 2018 , and thereafter: IN MILLIONS $3.0 Billion Credit Facility 2024 Notes and 2027 Notes Total 2019 $ — $ — $ — 2020 — — — 2021 — — — 2022 — — — 2023 1,143.0 — 1,143.0 Thereafter 300.0 1,200.0 1,500.0 Total debt $ 1,443.0 $ 1,200.0 $ 2,643.0

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value of Financial Instruments Fair value measurements are based on the assumptions that market participants would use in pricing the asset or liability. As a basis for considering assumptions in fair value measurements, a fair value hierarchy that distinguishes between market participant assumptions based on market data obtained from sources independent of the reporting entity (observable inputs that are classified within Levels 1 and 2 of the hierarchy) and the reporting entity’s own assumptions about market participant assumptions (unobservable inputs classified within Level 3 of the hierarchy) has been established. Level 1 inputs utilize quoted prices (unadjusted) in active markets for identical assets and liabilities that we have the ability to access. Level 2 inputs are inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. Level 2 inputs may include quoted prices for similar assets and liabilities in active markets, as well as inputs that are observable for the asset or liability (other than quoted prices), such as interest rates and yield curves that are observable at commonly quoted intervals. Level 3 inputs are unobservable inputs for the asset or liability that are typically based on an entity’s own assumptions, as there is little, if any, related market activity. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. Our assessment of the significance of a particular input to the fair value measurement requires judgment and considers factors specific to the asset or liability. The fair value of cash and cash equivalents, rent and other receivables, construction costs payable, dividends payable and accounts payable and accrued expenses approximate their carrying value because of the short-term nature of these financial instruments. The carrying value, exclusive of deferred financing costs, for the revolving credit facilities and the floating rate term loans approximate estimated fair value as of December 31, 2018 and 2017 , due to the floating rate nature of the interest rates and the stability of our credit ratings. The carrying value and fair value of other financial instruments are as follows (in millions): IN MILLIONS For the year ended December 31, 2018 2017 Carrying Value Fair Value Carrying Value Fair Value 2024 Notes $ 705.5 $ 684.1 $ 706.8 $ 728.0 2027 Notes 509.1 488.0 510.5 527.5 GDS Equity investment 185.5 185.5 175.6 175.6 The fair values of our 2024 Notes and 2027 Notes as of December 31, 2018 were based on the quoted market prices for these notes, which is considered Level 1 of the fair value hierarchy. The fair value of the equity investment in 2018 was based on the quoted market price for the stock which is considered Level 1 of the fair value hierarchy. For the year ended December 31, 2017, we recognized impairment losses of $58.0 million included in Impairment losses in our Consolidated Statement of Operations. We utilize estimates of the fair value of assets to determine impairment losses. These estimates include Level 3 inputs including market rents, expected occupancy and estimates of additional capital expenditures, and cashflows from each investment.

Dividends

Dividends	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Dividends	Dividends We have declared cash dividends on common shares and distributions on operating partnership units for the years ended December 31, 2018 and 2017 as presented in the table below: Record date Payment date Cash dividend per share or operating partnership unit March 31, 2017 April 14, 2017 $0.42 June 30, 2017 July 14, 2017 $0.42 September 29, 2017 October 13, 2017 $0.42 December 29, 2017 January 12, 2018 $0.42 March 29, 2018 April 13, 2018 $0.46 June 29, 2018 July 13, 2018 $0.46 September 28, 2018 October 12, 2018 $0.46 January 2, 2019 January 11, 2019 $0.46 As of December 31, 2018 and 2017 we had a dividend payable of $51.0 million and $41.8 million , respectively. On February 20, 2019 , we announced a regular cash dividend of $0.46 per common share payable to shareholders of record as of the close of business on March 29, 2019 . The dividend will be paid on April 12, 2019 .

Customer Leases

Customer Leases	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Customer Leases	Customer Leases Customer lease arrangements customarily contain provisions that allow for renewal or continuation on a month-to-month arrangement, and certain leases contain early termination rights. At lease inception, early termination is generally not deemed probable due to the significant economic penalty incurred by the lessee to exercise its termination right and to relocate their equipment. The future minimum lease payments to be received under non-cancellable operating leases, excluding month-to-month arrangements and metered power reimbursements, for the next five years are shown below: IN MILLIONS 2019 $ 647.6 2020 553.7 2021 453.0 2022 365.5 2023 284.4 Thereafter 835.9

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2018
Retirement Benefits [Abstract]
Employee Benefit Plans	Employee Benefit Plans Currently, our employees participate in health care plans sponsored by CyrusOne, which provide medical, dental, vision and prescription benefits. We incurred $3.3 million , $2.7 million and $4.4 million of expenses related to these plans for the years ended December 31, 2018 , 2017 and 2016 , respectively. CyrusOne offers a defined contribution 401(k) retirement savings plan to its employees. CyrusOne's matching contribution to its retirement savings plan was $1.8 million , $1.5 million and $1.5 million for the years ended December 31, 2018 , 2017 and 2016 , respectively.

Income (Loss) per Share

Income (Loss) per Share	12 Months Ended
	Dec. 31, 2018
Earnings Per Share [Abstract]
Income (Loss) per Share	Income (Loss) per Share Basic income (loss) per share is calculated using the weighted average number of shares of common stock outstanding during the period. In addition, net income (loss) applicable to participating securities and the participating securities are both excluded from the computation of basic income (loss) per share. Diluted income (loss) 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. On September 28, 2018, CyrusOne Inc. completed a public offering of 6.7 million shares of its common stock for $397.3 million , net of underwriting discounts and expenses of approximately $18.1 million . In connection with this offering, on September 25, 2018, CyrusOne Inc. entered into a forward sale agreement with Morgan Stanley & Co. LLC with respect to an additional 2.5 million shares of its common stock. On December 28, 2018, the Company effected a full physical settlement of the previously announced forward sale agreement entered into with Morgan Stanley & Co. LLC. Upon settlement, the Company issued all such shares to Morgan Stanley & Co. LLC in its capacity as forward purchaser, in exchange for net proceeds of approximately $148.2 million , in accordance with the provisions of the forward sales agreement. This agreement and the settlement thereof had no effect on our diluted share count at December 31, 2018. On August 15, 2016, CyrusOne Inc. completed a public offering of 3.4 million shares of its common stock for $164.8 million , net of underwriting discounts of approximately $6.9 million . In connection with this offering, on August 10, 2016, CyrusOne Inc. entered into (a) a forward sale agreement with Goldman, Sachs & Co. with respect to 3.4 million shares of its common stock, and (b) an additional forward sale agreement with Goldman, Sachs & Co. with respect to approximately 1.0 million shares of its common stock in connection with the underwriters' exercise of their option to purchase these shares. These agreements and the settlement thereof had no effect on our diluted share count at December 31, 2016. The following table reflects the computation of basic and diluted net (loss) income per share: IN MILLIONS, except per share amounts Year Ended Year Ended Year Ended For December 31, 2018 2017 2016 Basic Diluted Basic Diluted Basic Diluted Numerator: Net income (loss) $ 1.2 $ 1.2 $ (83.5 ) $ (83.5 ) $ 19.9 $ 19.9 Less: Restricted stock dividends (1.1 ) (1.1 ) (0.9 ) (0.9 ) (0.7 ) (0.7 ) Net income (loss) available to stockholders $ 0.1 $ 0.1 $ (84.4 ) $ (84.4 ) $ 19.2 $ 19.2 Denominator: Weighted average common outstanding-basic 99.8 99.8 88.9 88.9 78.3 78.3 Performance-based restricted stock and units (1) 0.6 — 0.7 Weighted average shares outstanding-diluted 100.4 88.9 79.0 EPS: Net income (loss) per share-basic $ — $ (0.95 ) $ 0.24 Effect of dilutive shares: Net income (loss) per share-diluted $ — $ (0.95 ) $ 0.24 (1) We have excluded 0.4 million weighted average shares of restricted stock, and 0.1 million of weighted average stock options which are securities convertible into common stock from our diluted earnings per share as of December 31, 2017. These amounts were deemed anti-dilutive.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stockholders' Equity	Stockholders' Equity Capitalization During the year ended December 31, 2018 and 2017 , we sold 12.2 million and 12.8 million shares of common stock, respectively, at an average price of $59.28 and $56.10 , respectively. At December 31, 2018 , the Company had approximately 108.3 million shares of common stock outstanding. Stock Plans Stock-based compensation expense was as follows: For the periods ended December 31, 2018 2017 2016 Founders $ — $ — $ 0.3 2013 Grants — — 0.1 2014 Grants — 0.1 1.2 2015 Grants 0.4 1.8 3.5 2016 Grants 5.7 6.6 7.2 2017 Grants 4.6 6.2 — 2018 Grants 6.8 — — Total $ 17.5 $ 14.7 $ 12.3 The board of directors of CyrusOne Inc. adopted the 2012 Long-Term Incentive Plan ("LTIP"), prior to the IPO, 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, restricted stock units, 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 December 31, 2018 , were approximately 5.1 million . Shares vest according to each agreement and as long as the employee remains employed with the Company. The Company has granted awards with time-based vesting, performance-based vesting and market-based vesting features. The performance-based vesting metrics granted have varied and are described in each of the grant years below. The market-based metric is total stockholder return (TSR) compared to the MSCI US REIT Index (REIT Index) as defined in the award agreements. The market-based restricted stock/units vest annually based upon the achievement of certain criteria for each of the three -year measurement periods. In each of the first two years vesting is limited to 100% of the target. If at the end of the third year total performance over the three -year period exceeds the REIT Index by 2% or more, up to 200% of these awards may vest. The market-based awards will vest based on the below scales. The scales are linear between each point and awards are interpolated between the points. - If CyrusOne's TSR is less than the return of the REIT Index equals 0% - If CyrusOne's TSR is equal to or greater than the return of the REIT Index equals 100% ; up to 200% if CyrusOne's TSR exceeds the return of the REIT Index by 2% - If CyrusOne's TSR exceeds the return of the REIT Index, but is negative, any calculated vesting amount will be reduced by 50% 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. 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 vesting and settlement of the units. 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. The compensation expense for the year ended December 31, 2016 includes $0.8 million due to the acceleration of equity awards of a senior executive who left the Company. The compensation expense for the year ended December 31, 2015 includes $2.4 million due to the acceleration of equity awards of two senior executives who left the Company. Founders Grants On January 24, 2013, the Company granted one million shares of time-based restricted stock, which had an aggregate value of $19.0 million on the grant date and vested on January 24, 2016 . 2013 Grants On April 17, 2013, the Company issued performance and market-based awards in the form of stock options and restricted stock. For these awards, vesting was tied 50% to the achievement of a non-GAAP financial measure related to the Company's performance (cumulative EBITDA targets, as defined in the agreement) using the scale, described below under 2014 Grants, over the 2013-2015 performance period, and 50% to a market-based performance measure. 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 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 . Total awards granted in 2013 had a grant date fair value of $25.4 million . As of December 31, 2018 , there was no unearned compensation related to the awards granted in 2013 as all such 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. For these awards, vesting was tied 50% to the achievement of a non-GAAP financial measure related to the Company's performance (cumulative Adjusted EBITDA targets, as defined in the agreement) over the 2014-2016 performance period, and 50% to a market-based performance measure. 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 cumulative EBITDA targets are based on the below scales. The scales are linear between each point and awards are interpolated between the points. - Below 90% of performance target equals 0% - At 90% of performance target equals 50% - At 100% of performance target equals 100% - At or above 115% of performance target equals up to 200% In addition, during the year ended December 31, 2014, the Company also granted from time-to-time a total of 46,313 additional time-based restricted shares which had an aggregate value of $1.0 million on the grant date. These shares cliff vested either one year after the grant date or three years after the grant date. Total awards granted in 2014 had a grant date fair value of $12.9 million . As of December 31, 2018 , there was no unearned compensation related to the awards granted in 2014 as all such 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 financial 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 periods. The first two years are capped at 100% of the target with a cumulative true-up to a maximum of 200% possible in year three. The performance-based awards will vest based on the same scales as the awards granted during 2014. In addition, during the year ended December 31, 2015, the Company also granted from time to time a total of 50,300 shares of time-based restricted stock and 67,012 shares of performance-based restricted stock for various new employee hires with vesting schedules ranging from annual to cliff vesting in three years. Total awards granted in 2015 had a grant date fair value of $13.8 million . As of December 31, 2018 , there was no unearned compensation related to the awards granted in 2015 as all such awards are fully vested. 2016 Grants On February 1, 2016, the Company issued 641,097 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 222,461 options with a grant date fair value of $6.99 . The performance-based metric is return on assets, which is a non-GAAP financial 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 to a maximum of 200% possible 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 performance-based awards will vest based on the same scales as the awards granted during 2014. In addition, during the year ended December 31, 2016, for various new employee hires, the following grants were made: • 5,894 shares of time-based restricted stock which cliff vest in three years from the date of each grant. • 47,667 shares of time-based restricted stock which vest annually on a pro rata basis over a three -year period from the date of each grant. Total awards granted in 2016 had a grant date fair value of $22.6 million . As of December 31, 2018 , unearned compensation representing the unvested portion of the awards granted in 2016 totaled $1.0 million , with a weighted average vesting period of 0.1 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. The Company granted 119,218 time-based restricted stock units that generally vest annually on a pro-rata basis over a three -year period and 18,179 shares of time-based restricted stock that generally vest over a one -year period with a grant date fair value of $48.13 , and 129,146 market-based restricted stock units, at target, with a grant date fair value of $63.23 . In addition, during the year ended December 31, 2017 the Company granted from time to time a total of 20,852 time-based restricted stock units that vest annually on a pro rata basis over a three -year period. Total awards granted in 2017 had a grant date fair value of $15.9 million . As of December 31, 2018 , unearned compensation representing the unvested portion of the awards granted in 2017 totaled $4.3 million , with a weighted average vesting period of 0.9 years. 2018 Grants On February 26, 2018, the Company issued time and market-based awards under the LTIP in the form of restricted stock units and restricted stock. The Company granted 161,797 time-based restricted stock units that generally vest annually on a pro-rata basis over a three -year period and 17,052 shares of time-based restricted stock that generally vest over a one -year period with a grant date fair value of $51.31 , and 160,266 market-based restricted stock units, at target, with a grant date fair value of $52.53 . In addition, during the year ended December 31, 2018 the Company granted from time to time a total of 40,249 time-based restricted stock units that vest annually on a pro rata basis over a three -year period. Total awards granted in 2018 had a grant date fair value of $20.2 million . As of December 31, 2018 , unearned compensation representing the unvested portion of the awards granted in 2018 totaled $12.5 million , with a weighted average vesting period of 1.7 years. Restricted Stock Units, Restricted Stock and Stock Option Activity The following tables summarize the unvested restricted stock units, restricted stock and stock options activity and the weighted average fair value of these shares at the date of grant for the year ended December 31, 2018 : Restricted Stock Units ("RSU") For the year ended December 31, 2018 Restricted Stock Units Weighted Average Grant Date Fair Value Non-vested at January 1 265,002 $ 56.08 Granted 362,312 53.23 Vested (88,425 ) 44.52 Forfeited (27,480 ) 52.97 Non-vested at December 31 511,409 $ 56.23 There were no non-vested restricted stock units at December 31, 2016. Restricted Stock ("RS") For the year ended December 31, 2018 Restricted Stock Weighted Average Grant Date Fair Value Non-vested at January 1 715,098 $ 32.21 Granted 17,052 51.31 Vested (253,015 ) 28.25 Forfeited (59,779 ) 29.69 Non-vested at December 31 419,356 $ 35.73 The non-vested restricted stock at December 31, 2016 were 1,274,713 . Stock Options For the year ended December 31, 2018 Options Weighted Average Exercise Price Outstanding at January 1 415,459 $ 31.67 Granted — — Exercised (14,236 ) 23.58 Forfeited or expired — — Outstanding at December 31 401,223 31.96 Exercisable at December 31 339,588 31.04 Vested and expected to vest 401,223 $ 31.96 The outstanding options at December 31, 2016 were 434,268 . The aggregate intrinsic value of options outstanding and options exercisable is based on the Company's closing stock price on the last trading day of the fiscal year for in-the-money options. The aggregate intrinsic value represents the cumulative difference between the fair market value of the underlying common stock and the option exercise prices. The total intrinsic value of options exercised during 2018 was $0.6 million , 2017 was $0.5 million and 2016 was $1.3 million . The aggregate intrinsic value of options outstanding at December 31, 2018 was $8.7 million . The aggregate intrinsic value of options exercisable at December 31, 2018 was $7.7 million . Stock Option Assumptions The following table summarizes the stock option assumptions for the years ended December 31, 2018 , 2017 and 2016 : Options Outstanding Options Exercisable Assumption Range Exercise Prices Number of Shares Weighted Average Remaining Contractual Terms (Years) Number of Shares Weighted Average Remaining Contractual Terms (Years) Risk-Free Interest Rate Expected Annual Dividend Yield Expected Terms in Years Expected Volatility 2016 $23.58 67,601 6.3 67,601 6.3 0.92% 3.4% 6.0 35% $28.42 143,358 8.1 47,786 8.1 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $30.74 12,719 8.6 4,240 8.6 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $36.99 210,590 9.1 18,530 9.1 1.47% - 1.64% 4.1% 5.5-6.5 27.5% - 35.0% 2017 $23.58 67,322 5.3 67,322 5.3 0.92% 3.4% 6.0 35% $28.42 143,358 7.1 95,572 7.1 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $30.74 12,719 7.6 8,479 7.6 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $36.99 192,060 8.1 64,022 8.1 1.47% - 1.64% 4.1% 5.5-6.5 27.5% - 35.0% 2018 $23.58 53,086 4.3 53,086 4.3 0.92% 3.4% 6.0 35% $28.42 143,358 6.1 143,358 6.1 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $30.74 12,719 6.6 12,719 6.6 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $36.99 192,060 6.8 130,425 6.7 1.47% - 1.64% 4.1% 5.5-6.5 27.5% - 35.0%

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions The Company has a strategic partnership with GDS, a developer and operator of high-performance, large-scale data centers in China. In connection with our investment in GDS, the Company entered into an agreement with GDS for the joint marketing of each company’s data centers. Also as a part of the agreement, the Company's Chief Executive Officer joined the board of directors of GDS on June 22, 2018. For the year ended December 31, 2018 , the Company incurred $0.9 million of commission and referral charges and accrued expenses payable to GDS. The commission and referral charges were capitalized as deferred leasing costs and will be amortized over the terms of the respective customer leases. No significant referral expense was recognized by the Company in 2018 or 2017. We have not recognized any referral revenue related to the agreement with GDS in 2018 or 2017. See Note 9, "Equity Investments", for additional information related to our GDS investment. The Company has a 10% equity interest in ODATA, a Brazilian headquartered company that specializes in providing colocation services to wholesale customers, such as hyperscale cloud providers, financial services and telecommunications companies, and also to enterprises across multiple industries. In connection with these investments, CyrusOne and ODATA entered a commercial agreement covering leasing activity with CyrusOne customers in the ODATA portfolio. Also as a part of the agreement, the Company's Chief Technology Officer joined the ODATA board of directors in October 2018.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
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. The REIT and certain of its subsidiaries are subject to state and local income taxes, franchise taxes, and gross receipts taxes. We have elected to treat certain of our subsidiaries as taxable REIT subsidiaries (TRSs). Our TRSs are subject to U.S. federal, state and local corporate income taxes. Our foreign subsidiaries are subject to corporate income taxes in the jurisdictions in which they operate. Income tax expense (benefit) for the years ended December 31, 2018 and 2017 as reported in the accompanying Consolidated Statement of Operations was comprised of the following: Year Ended December 31, IN MILLIONS 2018 2017 2016 Current Federal $ 1.0 $ 1.2 $ 0.6 State 2.0 1.8 1.2 Total current expense 3.0 3.0 1.8 Deferred: Federal — — — State — — — Foreign (2.4 ) — — Total deferred (benefit) expense (2.4 ) — — Total income tax expense 0.6 3.0 1.8 An income tax expense reconciliation between the U.S. statutory tax rate and the effective tax rate is as follows: Year Ended December 31, IN MILLIONS 2018 2017 2016 Income tax at U.S. federal statutory income tax rate $ 0.4 $ (28.2 ) $ 7.6 State and local taxes, net of federal income tax benefit 2.0 1.8 1.2 Impact of REIT status (2.1 ) 28.6 (7.2 ) Permanent differences (0.1 ) — Foreign tax rate differential 0.2 — Other 0.1 — — Valuation allowance 0.1 0.8 0.2 Income tax (benefit) expense $ 0.6 $ 3.0 $ 1.8 The effective tax rate on income from continuing operations differs from tax at the statutory rate primarily due to our status as a REIT and taxation of our foreign subsidiaries. Deferred tax assets and liabilities are recognized for the estimated future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. The components of the Company’s deferred tax assets and liabilities are as follows: Year Ended December 31, IN MILLIONS 2018 2017 Deferred tax assets Net operating loss carryforwards $ 15.1 $ 7.2 Accounts receivable/payable and other 7.4 — Capital leases 1.8 — Total gross deferred tax assets $ 24.3 $ 7.2 Valuation allowance (6.9 ) (7.2 ) Total gross deferred tax assets, net $ 17.4 $ — Deferred tax liabilities Fixed assets (73.5 ) — Intangibles $ (12.8 ) — Total gross deferred tax liabilities $ (86.3 ) — Total net deferred tax assets/(liabilities) $ (68.9 ) — On August 24, 2018, the Company completed the acquisition of Zenium. The Company recorded a deferred tax liability of $72.7 million in connection with the acquisition, which primarily related to differences between the carrying amounts of the assets and liabilities acquired and their tax bases in the jurisdictions in which they operate. As of December 31, 2018, the Company’s deferred tax assets were primarily attributable to U.S. state and local and foreign NOL carryforwards. A valuation allowance will be recorded to reduce deferred tax assets to amounts that are more likely than not to be realized. As of each reporting date, the Company’s management considers new evidence, both positive and negative, that could impact management’s view with regard to future realization of deferred tax assets. The Company has recorded a valuation allowance of $6.9 million as of December 31, 2018. The Company and its subsidiaries file tax returns in the U.S. federal jurisdiction, various state and local jurisdictions, and certain foreign jurisdictions. With few exceptions, the Company is no longer subject to examination of its U.S. federal, state and local tax returns for years prior to 2015. As of December 31, 2018, the Company as no liability for unrecognized tax benefits. If applicable, the Company will recognize interest and penalties related to unrecognized tax benefits as a component of tax expense.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases We lease certain data center facilities and equipment from third parties. Operating lease expense was $6.6 million , $8.2 million and $7.5 million for the years ended December 31, 2018 , 2017 and 2016 , respectively. Certain of these leases provide for renewal options with fixed rent escalations beyond the initial lease term. At December 31, 2018 , future minimum lease payments required under operating leases having initial or remaining non-cancellable lease terms in excess of one year are as follows: IN MILLIONS Total 2019 $ 5.0 2020 4.9 2021 3.7 2022 3.7 2023 3.5 Thereafter 43.4 Total $ 64.2 Capital Leases We use capital leases as a source of financing. See Note 13, Capital Lease Obligations and Lease Financing Arrangements, for future minimum principal payments. Standby Letters of Credit As of December 31, 2018 , CyrusOne Inc. had outstanding letters of credit of $8.0 million as security for obligations under the terms of our lessee agreements. Performance Guarantees Customer contracts generally require specified levels of performance related to uninterrupted service and cooling temperatures. If these performance standards are not met, we could be obligated to issue billing credits to the customer. Management assesses the probability that a performance standard will not be achieved. As of December 31, 2018 and 2017 , no accruals for performance guarantees were required. Indemnifications During the normal course of business, we make certain indemnities, commitments and guarantees under which we may be required to make payments in relation to certain transactions. These include (i) intellectual property indemnities to customers in connection with the use, sale and/or license of products and services, (ii) indemnities to vendors and service providers pertaining to claims based on our negligence or willful misconduct and (iii) indemnities involving the representations and warranties in certain contracts. In addition, we have made contractual commitments to several employees providing for payments upon the occurrence of certain prescribed events. The majority of these indemnities, commitments and guarantees do not provide for any limitation on the maximum potential for future payments that we could be obligated to make. Purchase Commitments We have entered into non-cancellable contracted commitments for construction of data center facilities and acquisition of equipment. As of December 31, 2018 , these commitments were approximately $281.9 million and are expected to be incurred over the next one to two years. In addition, we have entered into equipment and utility power contracts, which require minimum purchase commitments for power. These agreements range from one to two years and provide for payments for early termination or require minimum payments for the remaining term. As of December 31, 2018 , the minimum commitments for these arrangements were approximately $45.4 million . Contingencies CyrusOne is involved in legal, tax and regulatory proceedings arising from the conduct of its business activities. Liabilities are established for loss contingencies when losses associated with such claims are deemed to be probable, and the loss can be reasonably estimated. Based on information currently available and consultation with legal counsel, we believe that the outcome of all claims will not, individually or in the aggregate, have a material effect on our financial statements.

Guarantors

Guarantors	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Guarantors	Guarantors The 2024 Notes and 2027 Notes issued by CyrusOne LP (the “LP Co-Issuer”) and CyrusOne Finance Corp. (the “Finance Co-Issuer” and, together with the LP Co-Issuer, the “Co-Issuers”) are fully and unconditionally and jointly and severally guaranteed on a senior unsecured basis. The guarantors include CyrusOne Inc. (the “Parent Guarantor”), the General Partner and certain domestic wholly-owned subsidiaries of the Operating Partnership (together with the General Partner, the “Guarantor Subsidiaries”; the Guarantor Subsidiaries together with the Parent Guarantor, the “Guarantors”). As of December 31, 2018 and 2017 , non-guarantors are all of our foreign subsidiaries and certain domestic subsidiaries (collectively, the “Non-Guarantors”). The foreign subsidiaries we acquired upon our acquisition of Zenium are classified as Non-Guarantors. The indentures governing the 2024 Notes and 2027 Notes contain affirmative and negative covenants customarily found in indebtedness of this type, including covenants that 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 assets. 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 indenture. 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. Subject to the provisions of the indentures governing the 2024 Notes and 2027 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, • upon the LP Co-issuer designating such Guarantor as an excluded subsidiary under the terms of the indentures, • upon the defeasance or discharge of the 2024 Notes or 2027 Notes, as applicable, in accordance with the terms of the indentures, and • upon the 2024 Notes or 2027 Notes, as applicable, being rated investment grade by at least two rating agencies and no default or event of default shall have occurred and be continuing. The Parent Guarantor is a REIT whose only material asset is its ownership of operating partnership units of the LP Co-Issuer. The LP Co-Issuer and its subsidiaries hold substantially all the assets of the Company. The LP Co-Issuer conducts the operations of the business, along with its subsidiaries. The Finance Co-Issuer does not have any operations or revenues. The Guarantor Subsidiaries include substantially all of our domestic operations and include approximately 85% of our gross operating real estate. The Non-Guarantors include substantially all of our foreign operations, primarily in the United Kingdom, Germany and Singapore. The Non-Guarantors' assets also include the ownership of our equity investment in GDS of $185.5 million and $175.6 million as of December 31, 2018 , and 2017 , respectively. The following schedules present the consolidating balance sheets as of December 31, 2018 and 2017 , and the consolidating statements of operations, comprehensive income (loss) and cash flows for the years ended December 31, 2018 , 2017 and 2016 for the Parent Guarantor, General Partner, each Co-issuer, Guarantor Subsidiaries, and Non-Guarantors. Eliminations and consolidation adjustments primarily relate to the elimination of investments in subsidiaries and equity earnings (loss) related to investments in subsidiaries (in millions). Consolidating Balance Sheets IN MILLIONS As of December 31, 2018 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Total investment in real estate, net — — — — 3,611.2 644.9 36.9 4,293.0 Cash and cash equivalents — — — — 27.2 37.2 — 64.4 Investment in subsidiaries 2,216.9 22.2 3,122.5 — — — (5,361.6 ) — Rent and other receivables, net — — — — 93.3 12.9 — 106.2 Intercompany receivable 23.2 — 1,761.5 — 6.8 — (1,791.5 ) — Equity investment — — — — — 198.1 — 198.1 Goodwill — — — — 455.1 — — 455.1 Intangible assets, net — — — — 178.1 57.6 — 235.7 Other assets — — 0.5 — 219.8 19.7 — 240.0 Total assets $ 2,240.1 $ 22.2 $ 4,884.5 $ — $ 4,591.5 $ 970.4 $ (7,116.2 ) $ 5,592.5 Debt, net $ — $ — $ 2,624.7 — $ — $ — $ — $ 2,624.7 Intercompany payable — — 23.2 — 1,761.5 6.8 (1,791.5 ) — Capital lease obligations and lease financing arrangements — — — — 104.0 52.7 — 156.7 Accounts payable and accrued expenses — — 19.7 — 95.9 5.7 — 121.3 Construction costs payable — — — — 175.6 19.7 — 195.3 Dividends payable 51.0 — — — — — — 51.0 Deferred revenue and prepaid rents — — — — 144.9 3.7 — 148.6 Deferred tax liability — — — — — 68.9 — 68.9 Total liabilities 51.0 — 2,667.6 — 2,281.9 157.5 (1,791.5 ) 3,366.5 Total stockholders' equity 2,189.1 22.2 2,216.9 — 2,309.6 812.9 (5,324.7 ) 2,226.0 Total liabilities and equity $ 2,240.1 $ 22.2 $ 4,884.5 $ — $ 4,591.5 $ 970.4 $ (7,116.2 ) $ 5,592.5 IN MILLIONS As of December 31, 2017 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Total investment in real estate, net — — — — 3,014.9 25.8 17.7 3,058.4 Cash and cash equivalents — — — — 151.2 0.7 — 151.9 Investment in subsidiaries 1,718.0 17.2 2,190.2 — — — (3,925.4 ) — Rent and other receivables, net — — — — 84.6 2.6 — 87.2 Intercompany receivable 20.0 — 1,656.4 — — — (1,676.4 ) — Equity investment — — — — — 175.6 — 175.6 Goodwill — — — — 455.1 — — 455.1 Intangible assets, net — — — — 203.0 — — 203.0 Other assets — — 0.5 — 177.7 2.7 — 180.9 Total assets $ 1,738.0 $ 17.2 $ 3,847.1 $ — $ 4,086.5 $ 207.4 $ (5,584.1 ) $ 4,312.1 Debt, net $ — $ — $ 2,089.4 — $ — $ — $ — $ 2,089.4 Intercompany payable — — 20.0 — 1,656.4 — (1,676.4 ) — Capital lease obligations and lease financing arrangements — — — — 110.0 32.0 — 142.0 Accounts payable and accrued expenses — — 19.7 — 77.3 0.9 — 97.9 Construction costs payable — — — — 115.5 — — 115.5 Dividends payable 41.8 — — — — — — 41.8 Deferred revenue and prepaid rents — — — — 110.8 0.8 — 111.6 Total liabilities 41.8 — 2,129.1 — 2,070.0 33.7 (1,676.4 ) 2,598.2 Total stockholders' equity 1,696.2 17.2 1,718.0 — 2,016.5 173.7 (3,907.7 ) 1,713.9 Total liabilities and equity $ 1,738.0 $ 17.2 $ 3,847.1 $ — $ 4,086.5 $ 207.4 $ (5,584.1 ) $ 4,312.1 Consolidating Statements of Operations and Comprehensive Income (Loss) IN MILLIONS Year Ended December 31, 2018 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Revenue — — — — 799.7 21.7 — 821.4 Total operating expenses — — — — 700.2 31.5 — 731.7 Operating income — — — — 99.5 (9.8 ) — 89.7 Interest expense — — (110.6 ) — — (3.3 ) 19.2 (94.7 ) Unrealized gain on marketable equity investment — — — — — 9.9 — 9.9 Loss on early extinguishment of debt — — (3.1 ) — — — — (3.1 ) (Loss) income before income taxes — — (113.7 ) — 99.5 (3.2 ) 19.2 1.8 Income tax (expense) benefit — — — — (3.0 ) 2.4 — (0.6 ) Equity (loss) earnings related to investment in subsidiaries (28.9 ) (0.3 ) 84.8 — — — (55.6 ) — Net (loss) income (28.9 ) (0.3 ) (28.9 ) — 96.5 (0.8 ) (36.4 ) 1.2 Other comprehensive loss — — — — — (10.9 ) — (10.9 ) Comprehensive (loss) income $ (28.9 ) $ (0.3 ) $ (28.9 ) $ — $ 96.5 $ (11.7 ) $ (36.4 ) $ (9.7 ) IN MILLIONS Year Ended December 31, 2017 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Revenue — — — — 666.4 5.6 — 672.0 Total operating expenses — — — — 640.4 7.5 — 647.9 Operating income (loss) — — — — 26.0 (1.9 ) — 24.1 Interest expense — — (76.2 ) — — (2.6 ) 10.7 (68.1 ) Loss on early extinguishment of debt — — (36.5 ) — — — — (36.5 ) (Loss) income before income taxes — — (112.7 ) — 26.0 (4.5 ) 10.7 (80.5 ) Income tax expense — — — — (3.0 ) — — (3.0 ) Equity (loss) earnings related to investment in subsidiaries (18.7 ) (0.2 ) 94.0 — (4.6 ) — (70.5 ) — Net (loss) income (18.7 ) (0.2 ) (18.7 ) — 18.4 (4.5 ) (59.8 ) (83.5 ) Other comprehensive income — — — — — 75.5 — 75.5 Comprehensive (loss) income $ (18.7 ) $ (0.2 ) $ (18.7 ) $ — $ 18.4 $ 71.0 $ (59.8 ) $ (8.0 ) IN MILLIONS Year Ended December 31, 2016 Parent (1) General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Revenue — — — — 523.7 5.4 — 529.1 Total operating expenses — — — — 457.5 1.1 — 458.6 Operating income — — — — 66.2 4.3 — 70.5 Interest expense — — (49.1 ) — — (2.8 ) 3.1 (48.8 ) (Loss) income before income taxes — — (49.1 ) — 66.2 1.5 3.1 21.7 Income tax expense — — — — (1.8 ) — — (1.8 ) Equity earnings (loss) related to investment in subsidiaries 15.9 0.2 65.0 — 0.6 — (81.7 ) — Net income (loss) 15.9 0.2 15.9 — 65.0 1.5 (78.6 ) 19.9 Other comprehensive loss — — — — — (0.9 ) — (0.9 ) Comprehensive income (loss) $ 15.9 $ 0.2 $ 15.9 $ — $ 65.0 $ 0.6 $ (78.6 ) $ 19.0 Consolidating Statements of Cash Flows IN MILLIONS Year Ended December 31, 2018 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Net cash (used in) provided by operating activities — — (103.6 ) — 421.6 (27.9 ) 19.2 $ 309.3 Cash flows from investing activities: Asset acquisitions, primarily real estate, net of cash acquired — — — — — (462.8 ) — (462.8 ) Investment in real estate — — — — (814.6 ) (31.9 ) (19.2 ) (865.7 ) Equity investment — — — — — (12.6 ) — (12.6 ) Investment in subsidiaries (700.0 ) (7.0 ) (829.5 ) — — — 1,536.5 — Return of investment 181.1 — — — — — (181.1 ) — Intercompany borrowings 5.6 — (105.1 ) — (6.8 ) — 106.3 — Net cash (used in) provided by investing activities (513.3 ) (7.0 ) (934.6 ) — (821.4 ) (507.3 ) 1,442.5 (1,341.1 ) Cash flows from financing activities: Issuance of common stock, net 699.6 — — — — — — 699.6 Stock issuance costs — — — — — — — — Dividends paid (181.1 ) — (181.1 ) — — — 181.1 (181.1 ) Intercompany borrowings — — (5.6 ) — 105.1 6.8 (106.3 ) — Proceeds from debt, net — — 1,958.4 — — 29.9 — 1,988.3 Payments on debt — — (1,432.7 ) — — (114.7 ) — (1,547.4 ) Payments on capital lease obligations and lease financing arrangements — — — — (7.9 ) (1.6 ) — (9.5 ) Interest paid by lenders on issuance of the senior notes — — — — — — — — Tax payment upon exercise of equity awards (5.2 ) — — — — — — (5.2 ) Contributions/distributions from parent — 7.0 700.0 — 178.6 650.9 (1,536.5 ) — Net cash provided by (used in) financing activities 513.3 7.0 1,039.0 — 275.8 571.3 (1,461.7 ) 944.7 Effect of exchange rate changes on cash, cash equivalents and restricted cash — — (0.8 ) — — 0.4 — (0.4 ) Net (decrease) increase in cash, cash equivalents and restricted cash — — — — (124.0 ) 36.5 — (87.5 ) Cash, cash equivalents and restricted cash at beginning of period — — — — 151.2 0.7 — 151.9 Cash, cash equivalents and restricted cash at end of period $ — $ — $ — $ — $ 27.2 $ 37.2 $ — $ 64.4 IN MILLIONS Year Ended December 31, 2017 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Net cash (used in) provided by operating activities $ — $ — $ (60.3 ) $ — $ 339.7 $ (0.6 ) $ 10.7 $ 289.5 Cash flows from investing activities: Asset acquisitions, primarily real estate, net of cash acquired — — — — (492.3 ) — — (492.3 ) Investment in real estate — — — — (903.8 ) — (10.7 ) (914.5 ) Equity investment — — — — — (100.0 ) — (100.0 ) Investment in subsidiaries (705.3 ) (7.1 ) (705.3 ) — (0.7 ) — 1,418.4 — Return of investment 145.7 — — — — — (145.7 ) — Intercompany borrowings 6.5 — (598.8 ) — — 0.5 591.8 — Net cash (used in) provided by investing activities (553.1 ) (7.1 ) (1,304.1 ) — (1,396.8 ) (99.5 ) 1,853.8 (1,506.8 ) Cash flows from financing activities: Issuance of common stock, net 705.7 — — — — — — 705.7 Dividends paid (145.7 ) — (145.7 ) — — — 145.7 (145.7 ) Intercompany borrowings — — (6.5 ) — 598.2 — (591.7 ) — Proceeds from debt, net — — 2,558.4 — — — — 2,558.4 Payments on debt — — (1,749.8 ) — — — — (1,749.8 ) Payments on capital lease obligations and lease financing arrangements — — — — (8.6 ) (1.2 ) — (9.8 ) Interest paid by lenders on issuance of the senior notes — — 2.7 — — — — 2.7 Tax payment upon exercise of equity awards (6.9 ) — — — — — — (6.9 ) Contributions/distributions from parent — 7.1 705.3 — 605.3 100.8 (1,418.5 ) — Net cash provided by (used in) financing activities 553.1 7.1 1,364.4 — 1,194.9 99.6 (1,864.5 ) 1,354.6 Net increase (decrease) in cash, cash equivalents and restricted cash — — — — 137.8 (0.5 ) — 137.3 Cash, cash equivalents and restricted cash at beginning of period — — — — 13.4 1.2 — 14.6 Cash, cash equivalents and restricted cash at end of period $ — $ — $ — $ — $ 151.2 $ 0.7 $ — $ 151.9 IN MILLIONS Year Ended December 31, 2016 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Net cash (used in) provided by operating activities $ — $ — $ (45.4 ) $ — $ 221.8 $ — $ 4.2 $ 180.6 Cash flows from investing activities: Asset acquisitions, primarily real estate, net of cash acquired — — — — (131.1 ) — — (131.1 ) Investment in real estate — — — — (598.9 ) (1.1 ) — (600.0 ) Investment in subsidiaries (448.2 ) (4.5 ) (448.2 ) — — — 900.9 — Return of investment 112.3 — — — — — (112.3 ) — Intercompany borrowings 15.3 — (66.3 ) — — (0.5 ) 51.5 — Net cash (used in) provided by investing activities (320.6 ) (4.5 ) (514.5 ) — (730.0 ) (1.6 ) 840.1 (731.1 ) Cash flows from financing activities: Issuance of common stock, net 447.1 — — — — — — 447.1 Dividends paid (112.3 ) — (114.3 ) — — — 112.3 (114.3 ) Intercompany borrowings — — (15.3 ) — 71.0 — (55.7 ) — Proceeds from debt, net — — 701.3 — — — — 701.3 Payments on debt — — (460.0 ) — (1.5 ) — — (461.5 ) Payments on capital lease obligations and lease financing arrangements — — — — (8.0 ) (1.1 ) — (9.1 ) Tax payment upon exercise of equity awards (14.2 ) — — — — — — (14.2 ) Contributions/distributions from parent — 4.5 448.2 — 448.2 — (900.9 ) — Net cash provided by (used in) financing activities 320.6 4.5 559.9 — 509.7 (1.1 ) (844.3 ) 549.3 Net increase (decrease) in cash, cash equivalents and restricted cash — — — — 1.5 (2.7 ) — (1.2 ) Cash, cash equivalents and restricted cash at beginning of period — — — — 11.9 3.9 — 15.8 Cash, cash equivalents and restricted cash at end of period $ — $ — $ — $ — $ 13.4 $ 1.2 $ — $ 14.6

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information (Unaudited)	Quarterly Financial Information (Unaudited) The table below reflects the unaudited selected quarterly information for the years ended December 31, 2018 and 2017 : IN MILLIONS, except per share amounts 2018 First Quarter Second Quarter Third Quarter Fourth Total Revenue $ 196.6 $ 196.9 $ 206.6 $ 221.3 $ 821.4 Operating income 27.7 27.0 20.2 14.8 89.7 Net income (loss) 43.5 105.9 (42.4 ) (105.8 ) 1.2 Net income (loss) attributed to common shareholders 43.5 105.9 (42.4 ) (105.8 ) 1.2 Basic income (loss) per share 0.45 1.07 (0.43 ) $ (1.09 ) $ — Diluted income (loss) per share 0.45 1.06 (0.43 ) (1.08 ) — IN MILLIONS, except per share amounts 2017 First Second Quarter Third Quarter Fourth Quarter Total Revenue $ 149.3 $ 166.9 $ 175.3 $ 180.5 $ 672.0 Operating income (loss) 19.8 16.7 (36.3 ) 23.9 24.1 Net (loss) income (30.4 ) (0.8 ) (55.1 ) 2.8 (83.5 ) Net (loss) income attributed to common stockholders (30.4 ) (0.8 ) (55.1 ) 2.8 (83.5 ) Basic and diluted (loss) income per share $ (0.36 ) $ (0.01 ) $ (0.61 ) $ 0.03 $ (0.95 )

Schedule II. Valuation and Qual

Schedule II. Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II. Valuation and Qualifying Accounts	Schedule II. Valuation and Qualifying Accounts Beginning Charge (Deductions)/ End (dollars in millions) of Period to Expenses Additions of Period Allowance for Doubtful Accounts 2018 $ 2.1 $ 2.3 $ (2.7 ) $ 1.7 2017 2.1 0.2 (0.2 ) 2.1 2016 1.0 1.6 (0.5 ) 2.1 Deferred Tax Valuation Allowance 2018 $ 7.2 $ (0.3 ) $ — $ 6.9 2017 6.5 0.7 — 7.2 2016 6.3 0.2 — 6.5

Schedule III. Real Estate Prope

Schedule III. Real Estate Properties and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation Disclosure [Abstract]
Schedule III. Real Estate Properties and Accumulated Depreciation	Schedule III. Real Estate Properties and Accumulated Depreciation CyrusOne Inc. As of December 31, 2018 (dollars in millions) Initial Costs Cost Capitalized Subsequent to Acquisition Gross Carrying Amount Description Land Building and Improvements Equipment Land Building and Improvements Equipment Land Building and Improvements Equipment Accumulated Depreciation Acquisition Dallas - Carrollton $ 16.1 $ — $ — $ — $ 62.2 $ 272.5 $ 16.1 $ 62.2 $ 272.5 $ 104.0 2012 Houston - Houston West I 1.4 21.4 0.1 — 63.8 51.0 1.4 85.2 51.1 83.2 2010 Northern Virginia - Sterling II — — — — 28.8 112.4 — 28.8 112.4 26.8 2013 San Antonio III — — — — 40.2 99.0 — 40.2 99.0 19.5 2017 Cincinnati - 7th Street 0.9 42.2 — — 71.9 37.4 0.9 114.1 37.4 93.3 1999 Northern Virginia - Sterling V 14.5 — — — 80.8 295.8 14.5 80.8 295.8 26.0 2016 Northern Virginia - Sterling VI — — — — — 77.5 — — 77.5 0.9 2018 Somerset I 12.1 124.6 83.3 — 1.2 7.7 12.1 125.8 91.0 27.0 2017 Dallas - Lewisville — 46.2 2.2 — 30.6 37.4 — 76.8 39.6 70.7 2010 Totowa - Madison — 28.3 45.6 — 0.2 12.1 — 28.5 57.7 29.4 2015 Chicago - Aurora I 2.4 26.0 97.3 — 6.4 35.6 2.4 32.4 132.9 40.4 2016 Cincinnati - North Cincinnati 0.9 12.3 — — 65.6 12.4 0.9 77.9 12.4 42.2 2008 Phoenix - Chandler II — — — — 16.2 39.4 — 16.2 39.4 20.0 2014 Wappingers Falls I — 9.9 13.3 — 1.4 8.7 — 11.3 22.0 13.8 2015 San Antonio I 4.6 3.0 — — 28.7 35.3 4.6 31.7 35.3 30.9 2011 Houston - Houston West II 2.0 — — 0.7 22.9 50.9 2.7 22.9 50.9 33.7 2013 Phoenix - Chandler I 10.5 — — — 58.3 68.7 10.5 58.3 68.7 45.1 2011 Phoenix - Chandler III — 0.9 2.5 — 10.5 48.3 — 11.4 50.8 11.6 2016 Northern Virginia - Sterling I 6.9 — — — 20.2 60.4 6.9 20.2 60.4 24.6 2013 Raleigh-Durham I 2.1 73.5 71.3 — 6.3 4.1 2.1 79.8 75.4 21.8 2017 Houston - Galleria — 56.0 2.0 — 15.0 18.2 — 71.0 20.2 56.0 2010 Phoenix - Chandler VI 2.3 — — 0.1 23.3 100.3 2.4 23.3 100.3 10.4 2016 Northern Virginia - Sterling III — — — — 22.2 61.3 — 22.2 61.3 12.5 2017 Frankfurt I 11.2 31.0 106.2 — 94.5 72.6 11.2 125.5 178.8 5.3 2018 Austin II 2.0 — — — 23.4 8.7 2.0 23.4 8.7 16.9 2011 San Antonio II 6.7 — — 0.3 30.3 60.8 7.0 30.3 60.8 17.5 2013 Florence 2.2 7.7 — — 34.3 8.4 2.2 42.0 8.4 32.7 2005 Austin III 3.3 — — — 11.7 47.0 3.3 11.7 47.0 11.3 2015 Phoenix - Chandler IV — — — — 18.4 43.3 — 18.4 43.3 6.8 2017 San Antonio IV — — — — 42.1 48.2 — 42.1 48.2 5.4 2017 Cincinnati - Hamilton — 9.5 — — 34.2 7.9 — 43.7 7.9 29.9 2007 Northern Virginia - Sterling IV 4.6 9.6 0.1 — 10.4 75.9 4.6 20.0 76.0 12.9 2016 Phoenix - Chandler V — — — — 10.7 53.4 — 10.7 53.4 4.0 2017 London II — 19.9 58.7 — 5.3 16.1 — 25.2 74.8 4.4 2018 London I — 25.3 20.5 — 8.8 5.8 — 34.1 26.3 1.3 2018 Stamford - Riverbend* — 4.3 13.2 — (1.4 ) (5.4 ) — 2.9 7.8 5.0 2015 Cincinnati - Mason — — — — 20.3 1.7 — 20.3 1.7 14.8 2004 Cincinnati - Blue Ash* — 2.6 — — (1.9 ) 0.2 — 0.7 0.2 0.5 2009 Houston - Houston West III 7.1 — — 0.1 18.0 31.4 7.2 18.0 31.4 9.7 2013 Norwalk I* — 18.3 25.3 — (4.7 ) (15.2 ) — 13.6 10.1 4.5 2015 Chicago - Lombard 0.7 3.2 — — 1.5 8.1 0.7 4.7 8.1 7.7 2008 Stamford - Omega* — 3.2 0.6 — (0.6 ) 0.1 — 2.6 0.7 0.7 2015 Cincinnati - Goldcoast* 0.6 — — (0.4 ) 4.0 0.1 0.2 4.0 0.1 3.1 2007 Totowa - Commerce — 4.1 0.8 — — 0.9 — 4.1 1.7 1.3 2015 South Bend - Crescent — 1.1 — — 0.6 0.2 — 1.7 0.2 1.8 2008 South Bend - Monroe — — — — 2.5 0.4 — 2.5 0.4 1.8 2007 Singapore - Inter Business Park* — 9.0 — — (9.0 ) — — — — — 2011 Chicago - Aurora II 2.6 — — — 22.6 68.6 2.6 22.6 68.6 7.1 2016 Chicago - Aurora Tower — — — — 4.9 0.4 — 4.9 0.4 0.1 2018 (dollars in millions) Initial Costs Cost Capitalized Subsequent to Gross Carrying Amount Description Land Building and Equipment Land Building and Equipment Land Building and Equipment Accumulated Acquisition London - Great Bridgewater — 16.5 — — 10.3 1.2 — 26.8 1.2 4.2 2011 $ 117.7 $ 609.6 $ 543.0 $ 0.8 $ 1,067.9 $ 2,087.2 $ 118.5 $ 1,677.5 $ 2,630.2 $ 1,054.5 Land held for future development $ 176.4 $ — $ — $ — $ — $ — $ 176.4 $ — $ — $ — The aggregate cost of the total properties for federal income tax purposes was $6,186.5 million at December 31, 2018 . In addition, Construction in progress was $744.9 million as we continue to build data center facilities. * Reductions in Cost Capitalized Subsequent to Acquisition due to impairment losses recorded for the respective facility. Historical Cost and Accumulated Depreciation and Amortization The following table reconciles the historical cost and accumulated depreciation for the years ended December 31, 2018 , 2017 and 2016 . Years Ended December 31, (amounts in millions) 2018 2017 2016 Property Balance—beginning of period $ 3,840.8 $ 2,601.6 $ 1,827.6 Disposals (20.8 ) (3.4 ) (12.0 ) Impairments — (71.8 ) (4.9 ) Additions (acquisitions and improvements) 1,527.5 1,314.4 790.9 Balance, end of period (1) $ 5,347.5 $ 3,840.8 $ 2,601.6 Accumulated Depreciation Balance—beginning of period $ 782.4 $ 578.5 $ 435.6 Disposals (14.0 ) (1.9 ) (7.9 ) Impairments — (14.1 ) — Additions (depreciation and amortization expense) 286.1 219.9 150.8 Balance, end of period $ 1,054.5 $ 782.4 $ 578.5

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements are prepared on a consolidated basis. In addition, the accompanying financial statements have been prepared in accordance with generally accepted accounting principles in the U.S. (GAAP) and include the accounts of the Company, as well as all wholly-owned subsidiaries and any consolidated variable interest entities. All intercompany transactions and balances have been eliminated in consolidation.
Investments in Real Estate	Investment in Real Estate Acquisition of Properties Investment in real estate consist of land, buildings, improvements and integral equipment utilized in our data center operations. We expect most acquisitions to be an acquisition of assets rather than a business combination as our typical acquisitions consist of properties whereby substantially all the fair value of gross assets acquired is concentrated in a single asset set (land, building and in-place leases), which are treated as asset acquisitions. See Business Combinations and Asset Acquisitions herein. Business Combinations and Asset Acquisitions We evaluate whether an acquisition is a business combination or an asset acquisition by determining whether the set of assets is a business. Asset Acquisitions When substantially all of the fair value of gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, the transaction is accounted for as an asset acquisition. Asset acquisitions are recorded at the cumulative acquisition costs and allocated to the assets acquired and liabilities assumed on a relative fair value basis. The Company allocates the purchase price of real estate to identifiable tangible assets such as land, building, land improvements and tenant improvements acquired based on their fair value. In estimating the fair value of each component management considers appraisals, replacement cost, its own analysis of recently acquired and existing comparable properties, market rental data and other related information. Transaction costs associated with asset acquisitions are capitalized. Business Combinations When substantially all of the fair value is not concentrated in a group of similar identifiable assets, the set of assets will generally be considered a business and 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. The following discussion applies to our initial determination of fair value and the resulting subsequent accounting which is generally applicable to both asset acquisitions and business combinations. The fair value of any tangible real estate assets acquired is determined by valuing the building as if it were vacant, and the fair value is then allocated to land, buildings, equipment and improvements. Land values are derived from appraisals, and building and equipment values are calculated as replacement cost less depreciation or estimates of the relative fair value of these assets using net operating income capitalization rates, discounted cash flow analysis or similar methods. We determine in-place lease values based on our evaluation of the specific characteristics of each tenant’s lease agreement and by applying a fair value model. The estimates of fair value of in-place leases include an estimate of carrying costs during the expected lease up periods for the respective leasable area considering current market conditions. In estimating fair value of in-place leases, we consider items such as real estate taxes, insurance, leasing commissions, tenant improvements and other operating expenses to execute similar leases as well as projected rental revenue and carrying costs during the expected lease up period. We amortize the value of in-place leases acquired to expense over the approximate weighted average remaining term of the leases, adjusted for projected tenant turnover, on a composite basis. We determine the value of above-market and below-market in-place leases for acquired properties based on the present value (using an interest rate that reflects the risks associated with the leases acquired) of the difference between (1) the contractual amounts to be paid pursuant to the in-place leases and (2) estimates of current market lease rates for the corresponding in-place leases, measured over a period equal to (i) the remaining non-cancellable lease term for above-market leases, or (ii) the remaining non-cancellable lease term plus any fixed rate renewal options for below-market leases. We record the fair value of above-market and below-market leases as intangible assets or liabilities, and amortize them as an adjustment to revenue over the lease term. We determine the fair value of assumed debt by calculating the net present value of the scheduled debt service payments using current market-based terms for interest rates for debt with similar terms that management believes we could obtain on similar maturities. Any difference between the fair value and stated value of the assumed debt is recorded as a discount or premium and amortized over the remaining life of the loan. Capitalization of Costs We capitalize costs directly related to the development, pre-development or improvement of our investment in real estate, referred to as capital projects and other activities included within this paragraph. Costs associated with our capital projects are capitalized as incurred. If the project is abandoned, these costs are expensed during the period in which the project is abandoned. Costs considered for capitalization include, but are not limited to, construction costs, interest, real estate taxes, insurance, utilities and lease expense, if appropriate. We capitalize indirect costs such as personnel, office and administrative expenses that are directly related to our development projects based on an estimate of the time spent on the construction and development activities. These costs are capitalized only during the period in which activities necessary to ready an asset for its intended use are in progress and such costs are incremental and identifiable to a specific activity to get the asset ready for its intended use. We determine when the capitalization period begins and ends through communication with project and other managers responsible for the tracking and oversight of individual projects. In the event that the activities to ready the asset for its intended use are suspended, the capitalization period will cease until such activities are resumed. In addition, we capitalize initial direct costs incurred for successful origination of new leases. Costs incurred for maintaining and repairing our properties, which do not extend their useful lives, are expensed as incurred. Interest expense is capitalized based on actual qualifying capital expenditures from the period when development commences until the asset is ready for its intended use, at the weighted average borrowing rate during the period. These costs are included in investment in real estate and depreciated over the estimated useful life of the related assets. Impairment Losses When events or circumstances indicate that the carrying amount of a real estate investment may not be recoverable, we review the carrying value of the asset. When such impairment indicators exist, we review an estimate of the undiscounted future cash flows expected to result from the use of the asset and its eventual disposition and compare such amount to its carrying amount. If our undiscounted cash flows indicate that we are unable to recover the carrying value of the real estate investment, an impairment loss is recognized. An impairment loss is measured as the amount by which the real estate investment's carrying value exceeds its estimated fair value.
Business Combinations and Asset Acquisitions	Business Combinations and Asset Acquisitions We evaluate whether an acquisition is a business combination or an asset acquisition by determining whether the set of assets is a business. Asset Acquisitions When substantially all of the fair value of gross assets acquired is concentrated in a single identifiable asset or a group of similar identifiable assets, the transaction is accounted for as an asset acquisition. Asset acquisitions are recorded at the cumulative acquisition costs and allocated to the assets acquired and liabilities assumed on a relative fair value basis. The Company allocates the purchase price of real estate to identifiable tangible assets such as land, building, land improvements and tenant improvements acquired based on their fair value. In estimating the fair value of each component management considers appraisals, replacement cost, its own analysis of recently acquired and existing comparable properties, market rental data and other related information. Transaction costs associated with asset acquisitions are capitalized. Business Combinations When substantially all of the fair value is not concentrated in a group of similar identifiable assets, the set of assets will generally be considered a business and 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. The following discussion applies to our initial determination of fair value and the resulting subsequent accounting which is generally applicable to both asset acquisitions and business combinations. The fair value of any tangible real estate assets acquired is determined by valuing the building as if it were vacant, and the fair value is then allocated to land, buildings, equipment and improvements. Land values are derived from appraisals, and building and equipment values are calculated as replacement cost less depreciation or estimates of the relative fair value of these assets using net operating income capitalization rates, discounted cash flow analysis or similar methods. We determine in-place lease values based on our evaluation of the specific characteristics of each tenant’s lease agreement and by applying a fair value model. The estimates of fair value of in-place leases include an estimate of carrying costs during the expected lease up periods for the respective leasable area considering current market conditions. In estimating fair value of in-place leases, we consider items such as real estate taxes, insurance, leasing commissions, tenant improvements and other operating expenses to execute similar leases as well as projected rental revenue and carrying costs during the expected lease up period. We amortize the value of in-place leases acquired to expense over the approximate weighted average remaining term of the leases, adjusted for projected tenant turnover, on a composite basis. We determine the value of above-market and below-market in-place leases for acquired properties based on the present value (using an interest rate that reflects the risks associated with the leases acquired) of the difference between (1) the contractual amounts to be paid pursuant to the in-place leases and (2) estimates of current market lease rates for the corresponding in-place leases, measured over a period equal to (i) the remaining non-cancellable lease term for above-market leases, or (ii) the remaining non-cancellable lease term plus any fixed rate renewal options for below-market leases. We record the fair value of above-market and below-market leases as intangible assets or liabilities, and amortize them as an adjustment to revenue over the lease term. We determine the fair value of assumed debt by calculating the net present value of the scheduled debt service payments using current market-based terms for interest rates for debt with similar terms that management believes we could obtain on similar maturities. Any difference between the fair value and stated value of the assumed debt is recorded as a discount or premium and amortized over the remaining life of the l
Capitalization of Costs	Capitalization of Costs We capitalize costs directly related to the development, pre-development or improvement of our investment in real estate, referred to as capital projects and other activities included within this paragraph. Costs associated with our capital projects are capitalized as incurred. If the project is abandoned, these costs are expensed during the period in which the project is abandoned. Costs considered for capitalization include, but are not limited to, construction costs, interest, real estate taxes, insurance, utilities and lease expense, if appropriate. We capitalize indirect costs such as personnel, office and administrative expenses that are directly related to our development projects based on an estimate of the time spent on the construction and development activities. These costs are capitalized only during the period in which activities necessary to ready an asset for its intended use are in progress and such costs are incremental and identifiable to a specific activity to get the asset ready for its intended use. We determine when the capitalization period begins and ends through communication with project and other managers responsible for the tracking and oversight of individual projects. In the event that the activities to ready the asset for its intended use are suspended, the capitalization period will cease until such activities are resumed. In addition, we capitalize initial direct costs incurred for successful origination of new leases. Costs incurred for maintaining and repairing our properties, which do not extend their useful lives, are expensed as incurred. Interest expense is capitalized based on actual qualifying capital expenditures from the period when development commences until the asset is ready for its intended use, at the weighted average borrowing rate during the period. These costs are included in investment in real estate and depreciated over the estimated useful life of the related assets.
Impairment Losses	Impairment Losses When events or circumstances indicate that the carrying amount of a real estate investment may not be recoverable, we review the carrying value of the asset. When such impairment indicators exist, we review an estimate of the undiscounted future cash flows expected to result from the use of the asset and its eventual disposition and compare such amount to its carrying amount. If our undiscounted cash flows indicate that we are unable to recover the carrying value of the real estate investment, an impairment loss is recognized. An impairment loss is measured as the amount by which the real estate investment's carrying value exceeds its estimated fair value.
Cash and Cash Equivalents and Restricted Cash	Cash and Cash Equivalents and Restricted Cash 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 of three months or less. Restricted cash includes cash equivalents held in our name to collateralize standby letters of credit or its use is restricted by contract or regulation.
Equity Investment	Equity Investment We hold investments in various joint ventures where the Company evaluates its ability to influence the operating or financial decisions of the investee in applying the appropriate method of accounting for such investments. Influence tends to be more effective as the investor's percent of ownership in the voting rights of the investee increases. Our equity investments represent less than 20% of the voting rights of the investees and we do not exercise influence over the operating and financial decisions. Accordingly, we do not account for our equity investments using the equity method accounting. For further information about our equity investments, see Note 9. Equity Investments. Our investment in GDS Holdings Limited (“GDS”) is classified as “available for sale” and is carried at fair value. Effective beginning January 1, 2018, changes in the fair value are reported as a component of net income (loss). Prior to January 1, 2018, such changes in fair value were reported as a component of comprehensive income (loss). See “ Recently Adopted Accounting Pronouncements ” section below. Our other equity investment is carried at cost because we do not exercise influence over the operating and financial decisions of the venture and there is no readily determinable fair value and our investment is recorded at cost less impairment, if any. Dividends paid from operating profits are reported as a component of net income (loss), while other dividends are reported as a return of capital.
Goodwill	Goodwill We evaluate goodwill for possible impairment at least annually or upon the occurrence of events or circumstances that indicate that they would more likely than not reduce the fair value of a reporting unit below its carrying amount. For our annual impairment evaluation, we have the option of performing a qualitative or quantitative goodwill impairment analysis. A qualitative analysis, step zero, analyzes the macro-economic environment in which we operate for any significant changes such as deterioration in the market that the Company operates or overall financial performance such as declining cash flows. Also, entity specific changes are analyzed such as change in management, strategy or composition of reporting unit. This assessment of qualitative factors serves as a basis for determining whether it is necessary to perform the step one test. A quantitative analysis, step one, requires the Company to estimate the fair value of the reporting unit and compare the fair value to the carrying value to identify whether the value of the recorded goodwill is impaired. Changes in certain assumptions could have a significant impact on the impairment test for goodwill under step one. The most critical assumptions are projected future growth rates, operating margins, capital expenditures, tax rates, terminal values and discount rates. These assumptions are subject to change as our long-term plans and strategies are updated each year. During the fourth quarters of 2018, 2017 and 2016, we applied step zero and determined that the fair value of the reporting unit is substantially in excess of the carrying amount and therefore determined that incremental goodwill impairment testing was not necessary.
Rent and Other Receivables	Rent and Other Receivables Receivables consist principally of trade receivables from customers with expected credit losses 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.
Deferred Leasing and Financing Costs	Deferred Revenue and Prepaid Rents Deferred revenue is recorded when a customer makes a contractual payment in excess of revenues recognized in accordance with GAAP. Prepaid rent liability is recorded when a customer makes an advance payment or they are contractually obligated to pay any amounts in advance of the associated lease or service period.
Lease Financing Arrangements	Lease Financing Arrangements Lease financing arrangements represent leases of real estate where 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 consolidated balance sheets. These transactions generally do not qualify for sale-leaseback accounting due to our continued involvement in these data center operations.
Revenue Recognition	Revenue Recognition Our leasing revenue primarily consists of colocation rent, metered power reimbursements and interconnection revenue. We generally are not entitled to reimbursements for rental expenses including real estate taxes, insurance or other common area operating expenses. The revenues from colocation rent revenue, metered power reimbursements and interconnection are recognized under the lease accounting standard and managed services, equipment sales, installations and other services are recognized under the revenue accounting standard. An allowance for doubtful accounts is recognized when the collection of trade receivables is deemed to be unlikely. Colocation Rent Revenue and Metered Power Reimbursements Revenue Colocation rent revenues are generally billed monthly in advance based on the contracted power or leased space. Some contracts may provide initial free rent periods and rents that escalate over the term of the contract. If rents escalate without the lessee gaining access to or control over additional leased power or space, at the beginning of the lease term, the rental payments 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 power and or leased space, revenue is recognized in proportion to the additional power or space 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 as a straight-line receivable, which is included in other assets in our consolidated balance sheet. When customers make an advance payment in connection with a lease period or contractual obligation, deferred revenue is recorded. 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. The revenue for these types of leases is recorded in colocation lease revenue. Other leases provide that the customer is separately billed for power based upon actual or estimated metered usage. Metered power reimbursement revenue is generally billed one month in arrears, and an estimate of this revenue is accrued in the month that the associated power is provided and recorded in Metered power reimbursements on the Consolidated Statement of Operations. Revenue from Contracts with Customers We adopted the new revenue recognition standard effective January 1, 2018. The information in this section describes our current revenue recognition policies. See Note 4, Recently Adopted Accounting Pronouncements, for additional information related to the adoption. Service Revenue Managed services include the provisioning of a full-service managed data center, monitoring customer computer equipment, managing backups and storage, utilization reporting and other related ancillary information technology services. Management service contracts generally range from one to five years. Other services generally include installation of customer equipment, performing customer system re-boots, server cabinet and cage management, power monitoring, shipping and receiving, resolving technical issues, and other services requested by the customer. Installation services include mounting, wiring, and testing of customer owned equipment. The installation period is typically short term in duration, and accordingly, revenue from the installation of customer equipment is recognized at a point-in-time once the installation is complete and the performance obligation is satisfied. Service revenue is measured based on the consideration specified in the contract and recognized over time as we satisfy the performance obligation. As allowed under GAAP, we have adopted the practical expedient that allows us not to disclose information about remaining performance obligations that have original expected durations of one year or less, the amount of the transaction price allocated to the remaining performance obligations and when we expect to recognize that amount as revenue for the year. We have also adopted the “as invoiced” practical expedient, whereby the Company recognizes revenue in the amount that directly corresponds to the amount of value transferred to the customer.
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. Amortization expense is recognized over the estimated useful lives of finite-lived intangibles. Finite-lived intangibles include trademarks, customer relationships, favorable leasehold interests, in-place leases, trade names and deferred leasing costs.
Foreign Currency Translation and Transactions	Foreign Currency Translation and Transactions Gains or losses from translation of foreign operations where the local currency is the functional currency are included as components of other comprehensive income (loss). 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 exchange rates during the period. Gains or losses from foreign currency transactions are included in determining net income (loss).
Stock-Based Compensation	Stock-Based Compensation We have a stock-based incentive award plan for our employees and directors. Stock-based compensation expense associated with these awards is recognized in general and administrative expenses, property operating expenses and sales and marketing in our consolidated statements of operations. We measure stock-based compensation at the estimated fair value on the grant date and recognize the amortization of stock-based compensation expense over the requisite service period. Fair value is determined based on assumptions related to volatility, interest rates and our market and company performance.
Fair Value Measurements	Fair Value Measurements Fair value measurements are utilized in accounting for business combinations, asset acquisitions, testing of goodwill and other long-lived assets for impairment, recording unrealized gain/loss on available-for-sale securities 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.
Segment Information	Segment Information Our data centers have similar revenues and operating expenses across all geographic locations. The service offerings and delivery of services are provided in a similar manner, using the same types of facilities and similar technologies. Our chief operating decision maker, the Company's Chief Executive Officer, reviews our financial information on an aggregate basis and as a result, we have one reportable business segment.
Use of Estimates	Use of Estimates Preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the 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. Significant estimates include and are related to determining lease terms and revenue recognition, the fair value for purchase price allocations for business combinations and asset acquisitions, and the useful lives of real estate and other long-lived assets. Actual results may differ from these estimates and assumptions.
Reclassifications	Reclassifications Certain financial information has been revised to conform to the current year presentation due to changes in the significance of the particular activity. The following items have been reclassified: Balance Sheet as of December 31, 2017 • Land related to construction in progress ( $8.7 million ) and land held for future development ( $63.8 million ) were previously included in investment in real estate - land ( $72.5 million ). • Notes receivable and long-term installment contracts are classified within other assets. These items were previously included in rent and other receivables ( $3.3 million ). • Construction costs payable are classified in a separate liability and were previously included in accounts payable and accrued expenses ( $115.5 million ). • Dividends payable are classified in a separate liability and were previously included in accounts payable and accrued expenses ( $41.8 million ). • Lease finance arrangements are classified in capital lease obligations and lease financing arrangements. These items were previously included in a separate line for lease finance arrangements ( $131.9 million ). • Equity investment is classified in a separate asset account and was previously included in other assets ( $175.6 million ). Statement of Cash Flows for the year ended December 31, 2017 • The cash flow effect of the change in interest accrual is classified within accounts payable and accrued expenses. These items were previously combined with non-cash interest expense, net in the comparable prior year period ( $12.3 million ). • Debt issuance and debt extinguishment costs are classified within proceeds from debt, net. These items were previously included in separate lines, debt issuance costs ( $19.0 million ) and payment of debt extinguishment costs ( $30.4 million ), in the comparable prior year period. Statement of Cash Flows for the year ended December 31, 2016 • The cash flow effect of the change in interest accrual is classified within accounts payable and accrued expenses. These items were previously combined with non-cash interest expense, net in the comparable prior year period ( $1.3 million ). • Debt issuance costs are classified within proceeds from debt, net. This item was previously included in a separate line, debt issuance costs ( $8.7 million ) in the comparable prior year period. • The note payment is classified within payments on debt. This item was previously included in a separate line, payment of note payable ( $8.7 million ) in the comparable prior year period.
Recently Issued Accounting Standards	Recently Adopted Accounting Pronouncements On January 1, 2018, we adopted the Financial Accounting Standards Board ("FASB") pronouncement Accounting Standards Update ("ASU") 2014-09 with respect to revenue recognition. The revised guidance outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and superseded prior revenue recognition guidance, including industry-specific revenue guidance. The revised guidance replaced most existing revenue and real estate sale recognition guidance in GAAP. The standard specifically excludes lease contracts, which is our primary recurring revenue source; however, our revenue accounting for managed services and sales of real estate and equipment will follow the revised guidance. We adopted the new standard using the modified retrospective transition method, where financial statement presentations prior to the date of adoption are not adjusted. Transactions that were not closed as of the adoption date were adjusted to reflect the new standard and we recorded an adjustment to beginning retained earnings of $0.3 million . See Note 5 "Revenue Recognition" for further information regarding the adoption of the new accounting standard, including expanded quantitative and qualitative disclosures regarding revenue recognition. On January 1, 2018, we adopted ASU 2017-05, which requires the derecognition of a business in accordance with Accounting Standards Codification ("ASC") 810, Consolidations, including instances in which the business is considered in substance real estate. In cases where a controlling interest in real estate was sold but a noncontrolling interest is retained, we may record a gain or loss related to both the sold and retained interests. The adoption of this standard did not have an impact on our condensed consolidated financial statements, but depending on future transactions, may in the future. On January 1, 2018, we adopted ASU 2016-01 related to equity investments. Equity investments (except those accounted for under the equity method of accounting or those that result in consolidation of the investee) are to be measured at fair value with changes in fair value now recognized in net income. Previously changes in fair value for available for sale equity investments were recorded in other comprehensive income (loss). The adoption of the new standard was made through a cumulative-effect adjustment to beginning retained earnings of $75.6 million . Prior financial statement amounts were not adjusted. For the year ended December 31, 2018 , the unrealized gain on investment was $9.9 million . New Accounting Pronouncements In August 2018, the Securities and Exchange Commission ("SEC") issued Securities Act Release No. 33-10532, Disclosure Update and Simplification, which amends certain of its disclosure requirements and is intended to facilitate the disclosure of information to investors and simplify compliance without significantly altering the total mix of information provided to investors. The amendments became effective on November 5, 2018. Among the amendments is the requirement to present the changes in shareholders’ equity in the interim financial statements (either in a separate statement or footnote) in quarterly reports on Form 10-Q. Based on the effective date of the amendments and Exchange Act Forms Compliance and Disclosure Interpretation Question 105.09 issued by the staff of the SEC’s Division of Corporation Finance on September 25, 2018 and updated on October 4, 2018, the Company’s first presentation of changes in shareholders’ equity will be in its Form 10-Q for the quarter ending March 31, 2019. In August 2018, the FASB issued ASU 2018-15, which clarifies the accounting for implementation costs incurred in a hosting arrangement that is a service contract. Capitalization of these implementation costs are accounted for under the same guidance as implementation costs incurred to develop or obtain internal-use software and recorded as a prepaid asset. These capitalized costs are to be expensed ratably over the hosting arrangement term as operating expense, along with the service fees. The guidance is effective for periods beginning after December 15, 2019. Early adoption is allowed. The Company does not plan to early adopt this guidance and is evaluating the impact of the new standard. In August 2018, the FASB issued ASU 2018-13, which changes the fair value measurement disclosure requirements of ASC 820. Under this ASU, key provisions include new, eliminated and modified disclosure requirements. The guidance is effective for periods beginning after December 15, 2019. Early adoption is allowed. The Company does not plan to early adopt this guidance and is evaluating the impact of the new standard. In June 2018, the FASB issued ASU 2018-07, which simplifies the accounting for share-based payments granted to nonemployees for goods and services. Under this ASU, most of the guidance on such payments to nonemployees would be aligned with the requirements for share-based payments granted to employees. The Company accounts for its share-based payments to our board of director members in the same manner as employees. Other than to our board of director members, the Company does not award share-based payments to any other nonemployees. Therefore, we do not expect this accounting pronouncement to significantly impact our financial statements. The guidance is effective for periods beginning after December 15, 2018. Early adoption is allowed. In February 2016, the FASB issued ASU 2016-02, regarding the accounting for leases for both lessees and lessors. In July 2018, ASU 2016-02 was amended, providing another transition method by allowing companies to initially apply the new lease standard in the year of adoption and not the earliest comparative period. The lease standard amendment also provided a practical expedient for an accounting policy election for lessors, by class of underlying asset, to not separate nonlease components from the associated lease components as long as the timing and pattern of transfer are the same for the nonlease and lease components. Lessees will recognize a right-of-use asset and a lease liability for 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 adjusted for any initial direct costs of the lease, lease incentives or early lease payments. For income statement purposes, the FASB retained a dual classification model, requiring lessees to classify leases as either operating or finance. Operating leases will result in straight-line rent expense (similar to current operating leases) while finance leases will result in interest and amortization expense (similar to current capital leases). Classification will be based on criteria that are largely similar to those applied in current lease accounting. The new standard may be adopted using a modified retrospective transition and provides for certain practical expedients. We are evaluating the impact of ASU 2016-02 on our consolidated financial statements, where we believe the primary impact as a lessee will relate to leases in which we are deemed to be the accounting owner due to our involvement in the construction of the assets. Previously, under the old standard, these assets were capitalized as investments in real estate and a related financing obligation was recorded. Under the new standard, these assets and liabilities will be removed from the Company’s balance sheet and we will record a right-of-use asset and a corresponding lease liability. Additionally, under the new standard, a right-of-use asset and corresponding lease liability will be recorded for leases currently treated as operating leases. The accounting for lessors will remain largely unchanged from current GAAP; however, the new lease standard requires that lessors expense, on an as-incurred basis, certain initial direct costs that are not incremental in negotiating a lease. Under existing standards, these costs are capitalizable and therefore the new lease standard will result in certain of these costs being expensed as incurred after adoption. During the twelve months ended December 31, 2018 and 2017, we capitalized $1.7 million and $0.9 million , respectively, of internal costs related to our leasing activities. Further under current lessor accounting, a real estate lease could only be a sales-type lease if ownership of the real estate was transferred to the lessee. With the adoption of ASU 2016-02, there will no longer be an exclusion for real estate leases, where the same classification guidance applies to all leases. If, as lessor, our real estate leases would be classified as sales-type leases, the real estate asset would be eliminated, a net investment asset would be recognized generally equal to the present value of the minimum lease payments plus the unguaranteed residual value and a selling profit or loss. We are required to adopt ASU 2016-02 January 1, 2019, and plan to use the modified retrospective approach. In January 2018, the FASB issued ASU 2018-01, which permits an entity to elect a practical expedient to not evaluate land easements that were not previously accounted for as leases prior to the entity’s adoption of the new lease accounting standard. Once the new lease standard is adopted, it should be applied prospectively to all new or modified land easements. The Company expects to adopt this new guidance effective January 1, 2019, along with the new lease standard, and will continue to evaluate the impact of this new guidance until it becomes effective. In June 2016, the FASB issued ASU 2016-13 providing guidance which requires certain financial assets to be presented at the net amount expected to be collected. The guidance affects entities holding financial assets and net investment in leases that are not accounted for at fair value through net income. The guidance will apply to our trade receivables, notes receivable, net investments in leases and any other future financial assets that have the contractual right to receive cash that we may acquire in the future. The guidance is effective for periods beginning for us January 1, 2020. Early adoption is permitted. We are currently evaluating the impact of the new standard.

Revenue Recognition (Tables)

Revenue Recognition (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	For the year ended December 31, 2018 , revenue disaggregated by primary revenue stream is as follows (in millions). Year Ended December 31, 2018 Year Ended December 31, 2017 Colocation rent $ 644.6 $ 539.8 Metered power 104.0 70.2 Interconnection revenue 40.0 34.1 Equipment sales 11.9 7.3 Other revenue 20.9 20.6 Revenue $ 821.4 $ 672.0

Acquisitions and Purchase of _2

Acquisitions and Purchase of Fixed Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Business Combinations [Abstract]
Schedule of Assets Acquired and Liabilities Assumed	The following table summarizes the estimated fair values of all assets acquired at the date of acquisition: IN MILLIONS 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 Accounts payable (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 The consolidated financial statements of CyrusOne Inc. include the operating results of Zenium since the acquisition date, which was August 24, 2018. The following table summarizes the estimated fair values of all assets acquired at the date of acquisition: IN MILLIONS Investment in real estate $ 597.3 Cash and cash equivalents 12.7 Rent and other receivables 9.0 Intangible assets: Trade name 1.8 Leasehold interest 1.7 In-place leases 61.5 Other assets 1.1 Accounts payable (22.3 ) Deferred revenue (3.3 ) Capital lease obligations (25.0 ) Deferred tax liability (72.7 ) Debt (86.3 ) Net assets acquired attributable to CyrusOne Inc. 475.5 Cash acquired (12.7 ) Net cash paid at acquisition $ 462.8
Schedule of Gross Investment in Real Estate	As of December 31, 2018 and 2017, major components of our real estate investments and intangibles and related accumulated depreciation and amortization are as follows (in millions): December 31, 2018 December 31, 2017 Investment in Real Estate Intangibles Investment in Real Estate Intangibles Buildings and Improvements Equipment Customer Relationships In Place Leases Other Contractual Buildings and Improvements Equipment Customer Relationships In Place Leases Other Contractual Cost $ 1,677.5 $ 2,630.2 $ 247.1 $ 136.0 19.5 $ 1,371.4 $ 1,813.9 $ 247.1 $ 75.9 $ 16.1 Less: accumulated depreciation and amortization (481.8 ) (572.7 ) (137.9 ) (21.1 ) (7.9 ) (418.2 ) (364.2 ) (123.0 ) (7.1 ) (6.0 ) Net $ 1,195.7 $ 2,057.5 $ 109.2 $ 114.9 $ 11.6 $ 953.2 $ 1,449.7 $ 124.1 $ 68.8 $ 10.1 A schedule of our gross investment in real estate follows: IN MILLIONS As of December 31, 2018 2017 Land Building and Equipment Land Building and Equipment Dallas - Carrollton $ 16.1 $ 62.2 $ 272.5 $ 16.1 $ 61.8 $ 210.7 Houston - Houston West I 1.4 85.2 51.1 1.4 85.2 49.8 Northern Virginia - Sterling II — 28.8 112.4 — 28.8 112.3 San Antonio III — 40.2 99.0 — 40.3 96.8 Cincinnati - 7th Street 0.9 114.1 37.4 0.9 110.6 33.1 Northern Virginia - Sterling V 14.5 80.8 295.8 14.5 35.7 108.8 Somerset I 12.1 125.8 91.0 9.3 124.8 83.7 Dallas - Lewisville — 76.8 39.6 — 76.7 37.4 Totowa - Madison — 28.5 57.7 — 28.5 55.1 Chicago - Aurora I 2.4 32.4 132.9 2.4 32.4 125.0 Cincinnati - North Cincinnati 0.9 77.9 12.4 0.9 77.4 9.9 Phoenix - Chandler II — 16.2 39.4 — 16.2 38.9 Wappingers Falls I — 11.3 22.0 — 11.3 18.0 San Antonio I 4.6 31.7 35.3 4.6 31.7 34.8 Houston - Houston West II 2.7 22.9 50.9 2.7 22.8 50.1 Phoenix - Chandler I 10.5 58.3 68.7 10.5 58.2 65.9 Phoenix - Chandler III — 11.4 50.8 — 11.4 50.0 Northern Virginia - Sterling I 6.9 20.2 60.4 7.0 20.0 59.4 Raleigh-Durham I 2.1 79.8 75.4 2.1 78.0 76.0 Houston - Galleria — 71.0 20.2 — 68.6 17.6 Phoenix - Chandler VI 2.4 23.3 100.3 2.4 15.7 49.2 Northern Virginia - Sterling III — 22.2 61.3 — 22.2 61.3 Frankfurt I 11.2 125.5 178.8 — — — Austin II 2.0 23.4 8.7 2.0 23.4 7.2 San Antonio II 7.0 30.3 60.8 7.0 29.0 60.4 Florence 2.2 42.0 8.4 2.2 42.0 5.3 Austin III 3.3 11.7 47.0 3.3 10.6 33.9 Phoenix - Chandler IV — 18.4 43.3 — 18.3 40.9 San Antonio IV — 42.1 48.2 — — 17.9 Cincinnati - Hamilton — 43.7 7.9 — 50.2 6.0 Northern Virginia - Sterling IV 4.6 20.0 76.0 4.6 20.0 73.7 Phoenix - Chandler V — 10.7 53.4 — 5.9 20.5 London II — 25.2 74.8 — — — London I — 34.1 26.3 — — — London - Great Bridgewater — 26.8 1.2 — 28.4 1.1 Cincinnati - Mason — 20.3 1.7 — 20.3 1.6 Stamford - Riverbend — 2.9 7.8 — 2.9 6.9 Houston - Houston West III 7.2 18.0 31.4 7.2 17.9 30.7 Norwalk I* — 13.6 10.1 — 13.5 9.4 Chicago - Lombard 0.7 4.7 8.1 0.7 4.7 7.7 Stamford - Omega* — 2.6 0.7 — 2.6 0.7 Cincinnati - Blue Ash — 0.7 0.2 — 0.7 0.2 Totowa - Commerce — 4.1 1.7 — 4.1 1.6 South Bend - Crescent — 1.7 0.2 — 1.7 0.1 IN MILLIONS As of December 31, 2018 2017 Land Building and Equipment Land Building and Equipment South Bend - Monroe — 2.5 0.4 — 2.5 0.3 Chicago - Aurora II 2.6 22.6 68.6 2.6 8.3 42.9 Chicago - Aurora Tower — 4.9 0.4 — — — Dallas - Midway — — — — 2.0 0.4 Dallas - Marsh — — — — 0.1 0.6 Cincinnati - Goldcoast 0.2 4.0 0.1 0.2 4.0 0.1 Northern Virginia - Sterling VI — — 77.5 — — — Total $ 118.5 $ 1,677.5 $ 2,630.2 $ 104.6 $ 1,371.4 $ 1,813.9 Land held for future development $ 176.4 $ — $ — $ 63.8 $ — $ —

Investment in Real Estate (Tabl

Investment in Real Estate (Tables)	12 Months Ended
	Dec. 31, 2018
Real Estate [Abstract]
Schedule of Gross Investment in Real Estate	As of December 31, 2018 and 2017, major components of our real estate investments and intangibles and related accumulated depreciation and amortization are as follows (in millions): December 31, 2018 December 31, 2017 Investment in Real Estate Intangibles Investment in Real Estate Intangibles Buildings and Improvements Equipment Customer Relationships In Place Leases Other Contractual Buildings and Improvements Equipment Customer Relationships In Place Leases Other Contractual Cost $ 1,677.5 $ 2,630.2 $ 247.1 $ 136.0 19.5 $ 1,371.4 $ 1,813.9 $ 247.1 $ 75.9 $ 16.1 Less: accumulated depreciation and amortization (481.8 ) (572.7 ) (137.9 ) (21.1 ) (7.9 ) (418.2 ) (364.2 ) (123.0 ) (7.1 ) (6.0 ) Net $ 1,195.7 $ 2,057.5 $ 109.2 $ 114.9 $ 11.6 $ 953.2 $ 1,449.7 $ 124.1 $ 68.8 $ 10.1 A schedule of our gross investment in real estate follows: IN MILLIONS As of December 31, 2018 2017 Land Building and Equipment Land Building and Equipment Dallas - Carrollton $ 16.1 $ 62.2 $ 272.5 $ 16.1 $ 61.8 $ 210.7 Houston - Houston West I 1.4 85.2 51.1 1.4 85.2 49.8 Northern Virginia - Sterling II — 28.8 112.4 — 28.8 112.3 San Antonio III — 40.2 99.0 — 40.3 96.8 Cincinnati - 7th Street 0.9 114.1 37.4 0.9 110.6 33.1 Northern Virginia - Sterling V 14.5 80.8 295.8 14.5 35.7 108.8 Somerset I 12.1 125.8 91.0 9.3 124.8 83.7 Dallas - Lewisville — 76.8 39.6 — 76.7 37.4 Totowa - Madison — 28.5 57.7 — 28.5 55.1 Chicago - Aurora I 2.4 32.4 132.9 2.4 32.4 125.0 Cincinnati - North Cincinnati 0.9 77.9 12.4 0.9 77.4 9.9 Phoenix - Chandler II — 16.2 39.4 — 16.2 38.9 Wappingers Falls I — 11.3 22.0 — 11.3 18.0 San Antonio I 4.6 31.7 35.3 4.6 31.7 34.8 Houston - Houston West II 2.7 22.9 50.9 2.7 22.8 50.1 Phoenix - Chandler I 10.5 58.3 68.7 10.5 58.2 65.9 Phoenix - Chandler III — 11.4 50.8 — 11.4 50.0 Northern Virginia - Sterling I 6.9 20.2 60.4 7.0 20.0 59.4 Raleigh-Durham I 2.1 79.8 75.4 2.1 78.0 76.0 Houston - Galleria — 71.0 20.2 — 68.6 17.6 Phoenix - Chandler VI 2.4 23.3 100.3 2.4 15.7 49.2 Northern Virginia - Sterling III — 22.2 61.3 — 22.2 61.3 Frankfurt I 11.2 125.5 178.8 — — — Austin II 2.0 23.4 8.7 2.0 23.4 7.2 San Antonio II 7.0 30.3 60.8 7.0 29.0 60.4 Florence 2.2 42.0 8.4 2.2 42.0 5.3 Austin III 3.3 11.7 47.0 3.3 10.6 33.9 Phoenix - Chandler IV — 18.4 43.3 — 18.3 40.9 San Antonio IV — 42.1 48.2 — — 17.9 Cincinnati - Hamilton — 43.7 7.9 — 50.2 6.0 Northern Virginia - Sterling IV 4.6 20.0 76.0 4.6 20.0 73.7 Phoenix - Chandler V — 10.7 53.4 — 5.9 20.5 London II — 25.2 74.8 — — — London I — 34.1 26.3 — — — London - Great Bridgewater — 26.8 1.2 — 28.4 1.1 Cincinnati - Mason — 20.3 1.7 — 20.3 1.6 Stamford - Riverbend — 2.9 7.8 — 2.9 6.9 Houston - Houston West III 7.2 18.0 31.4 7.2 17.9 30.7 Norwalk I* — 13.6 10.1 — 13.5 9.4 Chicago - Lombard 0.7 4.7 8.1 0.7 4.7 7.7 Stamford - Omega* — 2.6 0.7 — 2.6 0.7 Cincinnati - Blue Ash — 0.7 0.2 — 0.7 0.2 Totowa - Commerce — 4.1 1.7 — 4.1 1.6 South Bend - Crescent — 1.7 0.2 — 1.7 0.1 IN MILLIONS As of December 31, 2018 2017 Land Building and Equipment Land Building and Equipment South Bend - Monroe — 2.5 0.4 — 2.5 0.3 Chicago - Aurora II 2.6 22.6 68.6 2.6 8.3 42.9 Chicago - Aurora Tower — 4.9 0.4 — — — Dallas - Midway — — — — 2.0 0.4 Dallas - Marsh — — — — 0.1 0.6 Cincinnati - Goldcoast 0.2 4.0 0.1 0.2 4.0 0.1 Northern Virginia - Sterling VI — — 77.5 — — — Total $ 118.5 $ 1,677.5 $ 2,630.2 $ 104.6 $ 1,371.4 $ 1,813.9 Land held for future development $ 176.4 $ — $ — $ 63.8 $ — $ —

Notes Receivable (Tables)

Notes Receivable (Tables)	12 Months Ended
	Dec. 31, 2018
Receivables [Abstract]
Schedule of notes receivable	The carrying amount of notes receivable was $2.1 million and $3.3 million as of December 31, 2018 and 2017 , respectively, and consisted of the following: IN MILLIONS For the year ended December 31, 2018 2017 Note 1 $ 1.4 $ 1.8 Note 2 0.3 0.6 Note 3 — 0.5 Note 4 0.3 0.4 Note 5 0.1 — Total $ 2.1 $ 3.3

Goodwill, Intangible and Othe_2

Goodwill, Intangible and Other Long-Lived Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Carrying Value of Major Classes of Intangible Assets	Summarized below are the carrying values for the major classes of intangible assets: IN MILLIONS For the year ended December 31, 2018 2017 Weighted- Gross Carrying Amount Accumulated Amortization Total Gross Carrying Amount Accumulated Amortization Total Customer relationships 11 $ 247.1 $ (137.9 ) $ 109.2 $ 247.1 $ (123.0 ) $ 124.1 Trademark/tradename 6 11.5 (6.7 ) 4.8 9.7 (5.3 ) 4.4 Favorable leasehold interest 36 5.7 (0.7 ) 5.0 4.1 (0.5 ) 3.6 In place customer leases 6 136.0 (21.1 ) 114.9 75.9 (7.1 ) 68.8 Above and below market leases 7 2.3 (0.5 ) 1.8 2.3 (0.2 ) 2.1 Total $ 402.6 $ (166.9 ) $ 235.7 $ 339.1 $ (136.1 ) $ 203.0
Schedule of Estimated Amortization Expense for Finite-Lived Intangible Assets	The following table presents estimated amortization expense for each of the next five years and thereafter, commencing January 1, 2019 : IN MILLIONS Total 2019 $ 40.2 2020 39.0 2021 31.8 2022 28.5 2023 20.7 Thereafter 75.5 Total $ 235.7

(Tables)

(Tables)	12 Months Ended
	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Schedule of Other Assets	As of December 31, 2018 and 2017 , the components of other assets are as follows (in millions): December 31, 2018 December 31, 2017 Straight line receivables, net $ 128.7 $ 100.0 Deferred leasing and other contract costs 43.6 33.7 Prepaid expenses 26.4 20.0 Non-real estate assets, net 18.4 16.7 Other 22.9 10.5 Total $ 240.0 $ 180.9

Capital Lease Obligations and_2

Capital Lease Obligations and Lease Financing Arrangements (Tables)	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Schedule of Capital Lease Obligations and Lease Financing Arrangements	As of December 31, 2018 and 2017 , capital lease obligations and lease financing arrangements are as follows (in millions): December 31, 2018 December 31, 2017 Capital lease obligations $ 33.4 $ 10.1 Lease financing arrangements 123.3 131.9 Total $ 156.7 $ 142.0
Schedule of Future Minimum Principal Payments of the Capital Lease Obligations and Lease Financing Arrangements	The following table summarizes aggregate minimum principal payments of the capital lease obligations for the five years subsequent to December 31, 2018 , and thereafter (in millions): Capital Leases 2019 $ 2.7 2020 2.8 2021 2.9 2022 2.0 2023 1.0 Thereafter 22.0 Total $ 33.4 The following table summarizes aggregate maturities of total future value and present value of the minimum payments associated with our lease financing arrangements for the five years subsequent to December 31, 2018 , and thereafter: IN MILLIONS Future Value of Payments Interest Present Value of Payments 2019 $ 15.0 $ 7.3 $ 7.7 2020 27.6 6.6 21.0 2021 11.4 5.7 5.7 2022 11.6 5.4 6.2 2023 10.0 4.1 5.9 Thereafter 89.1 12.3 76.8 Total lease financing arrangements $ 164.7 $ 41.4 $ 123.3

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Debt Disclosure [Abstract]
Schedule of Long-term debt Instruments	As of December 31, 2018 and 2017 , the components of debt are as follows (unless otherwise noted, interest rate and maturity date information are as of December 31, 2018 ) (in millions): December 31, 2018 December 31, 2017 Interest Rate (a) Maturity Date $3.0 Billion Credit Facility: $1.7 Billion Revolving Credit Facility $ 143.0 $ — Monthly EURIBOR + 1.45% March 2022 (b) 2023 Term Loan 1,000.0 — Monthly LIBOR + 1.40% March 2023 2025 Term Loan 300.0 — Monthly LIBOR + 1.70% March 2025 $2.0 Billion Credit Facility: $1.1 Billion Revolving Credit Facility — — Monthly LIBOR + 1.55% N/A 2021 Term Loan — 250.0 Monthly LIBOR + 1.50% N/A 2022 Term Loan — 650.0 Monthly LIBOR + 1.50% N/A 2024 Notes, including bond premium of $5.5 million 705.5 706.8 5.000 % March 2024 2027 Notes, including bond premium of $9.1 million 509.1 510.5 5.375 % March 2027 Deferred financing costs (32.9 ) (27.9 ) — — Total $ 2,624.7 $ 2,089.4 (a) - Monthly LIBOR at December 31, 2018 was 2.53% . (b) - The Company may exercise a one -year extension option, subject to certain conditions.
Schedule of Maturities of Long-term Debt	The following table summarizes aggregate maturities of the $3.0 Billion Credit Facility and 2024 Notes and 2027 Notes for the five years subsequent to December 31, 2018 , and thereafter: IN MILLIONS $3.0 Billion Credit Facility 2024 Notes and 2027 Notes Total 2019 $ — $ — $ — 2020 — — — 2021 — — — 2022 — — — 2023 1,143.0 — 1,143.0 Thereafter 300.0 1,200.0 1,500.0 Total debt $ 1,443.0 $ 1,200.0 $ 2,643.0

Fair Value of Financial Instr_2

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2018
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): IN MILLIONS For the year ended December 31, 2018 2017 Carrying Value Fair Value Carrying Value Fair Value 2024 Notes $ 705.5 $ 684.1 $ 706.8 $ 728.0 2027 Notes 509.1 488.0 510.5 527.5 GDS Equity investment 185.5 185.5 175.6 175.6

Dividends (Tables)

Dividends (Tables)	12 Months Ended
	Dec. 31, 2018
Stockholders' Equity Note [Abstract]
Schedule of declared cash dividends on common shares and distributions on operating partnership units	We have declared cash dividends on common shares and distributions on operating partnership units for the years ended December 31, 2018 and 2017 as presented in the table below: Record date Payment date Cash dividend per share or operating partnership unit March 31, 2017 April 14, 2017 $0.42 June 30, 2017 July 14, 2017 $0.42 September 29, 2017 October 13, 2017 $0.42 December 29, 2017 January 12, 2018 $0.42 March 29, 2018 April 13, 2018 $0.46 June 29, 2018 July 13, 2018 $0.46 September 28, 2018 October 12, 2018 $0.46 January 2, 2019 January 11, 2019 $0.46

Customer Leases (Tables)

Customer Leases (Tables)	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	The future minimum lease payments to be received under non-cancellable operating leases, excluding month-to-month arrangements and metered power reimbursements, for the next five years are shown below: IN MILLIONS 2019 $ 647.6 2020 553.7 2021 453.0 2022 365.5 2023 284.4 Thereafter 835.9 At December 31, 2018 , future minimum lease payments required under operating leases having initial or remaining non-cancellable lease terms in excess of one year are as follows: IN MILLIONS Total 2019 $ 5.0 2020 4.9 2021 3.7 2022 3.7 2023 3.5 Thereafter 43.4 Total $ 64.2

Income (Loss) per Share (Tables

Income (Loss) per Share (Tables)	12 Months Ended
	Dec. 31, 2018
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: IN MILLIONS, except per share amounts Year Ended Year Ended Year Ended For December 31, 2018 2017 2016 Basic Diluted Basic Diluted Basic Diluted Numerator: Net income (loss) $ 1.2 $ 1.2 $ (83.5 ) $ (83.5 ) $ 19.9 $ 19.9 Less: Restricted stock dividends (1.1 ) (1.1 ) (0.9 ) (0.9 ) (0.7 ) (0.7 ) Net income (loss) available to stockholders $ 0.1 $ 0.1 $ (84.4 ) $ (84.4 ) $ 19.2 $ 19.2 Denominator: Weighted average common outstanding-basic 99.8 99.8 88.9 88.9 78.3 78.3 Performance-based restricted stock and units (1) 0.6 — 0.7 Weighted average shares outstanding-diluted 100.4 88.9 79.0 EPS: Net income (loss) per share-basic $ — $ (0.95 ) $ 0.24 Effect of dilutive shares: Net income (loss) per share-diluted $ — $ (0.95 ) $ 0.24 (1) We have excluded 0.4 million weighted average shares of restricted stock, and 0.1 million of weighted average stock options which are securities convertible into common stock from our diluted earnings per share as of December 31, 2017. These amounts were deemed anti-dilutive.

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2018
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Compensation Expense	Stock-based compensation expense was as follows: For the periods ended December 31, 2018 2017 2016 Founders $ — $ — $ 0.3 2013 Grants — — 0.1 2014 Grants — 0.1 1.2 2015 Grants 0.4 1.8 3.5 2016 Grants 5.7 6.6 7.2 2017 Grants 4.6 6.2 — 2018 Grants 6.8 — — Total $ 17.5 $ 14.7 $ 12.3
Schedule of Restricted Stock Awards Activity	The following tables summarize the unvested restricted stock units, restricted stock and stock options activity and the weighted average fair value of these shares at the date of grant for the year ended December 31, 2018 : Restricted Stock Units ("RSU") For the year ended December 31, 2018 Restricted Stock Units Weighted Average Grant Date Fair Value Non-vested at January 1 265,002 $ 56.08 Granted 362,312 53.23 Vested (88,425 ) 44.52 Forfeited (27,480 ) 52.97 Non-vested at December 31 511,409 $ 56.23 There were no non-vested restricted stock units at December 31, 2016. Restricted Stock ("RS") For the year ended December 31, 2018 Restricted Stock Weighted Average Grant Date Fair Value Non-vested at January 1 715,098 $ 32.21 Granted 17,052 51.31 Vested (253,015 ) 28.25 Forfeited (59,779 ) 29.69 Non-vested at December 31 419,356 $ 35.73
Schedule of Unvested Stock Options	Stock Options For the year ended December 31, 2018 Options Weighted Average Exercise Price Outstanding at January 1 415,459 $ 31.67 Granted — — Exercised (14,236 ) 23.58 Forfeited or expired — — Outstanding at December 31 401,223 31.96 Exercisable at December 31 339,588 31.04 Vested and expected to vest 401,223 $ 31.96
Schedule of Option Valuation Assumptions	The following table summarizes the stock option assumptions for the years ended December 31, 2018 , 2017 and 2016 : Options Outstanding Options Exercisable Assumption Range Exercise Prices Number of Shares Weighted Average Remaining Contractual Terms (Years) Number of Shares Weighted Average Remaining Contractual Terms (Years) Risk-Free Interest Rate Expected Annual Dividend Yield Expected Terms in Years Expected Volatility 2016 $23.58 67,601 6.3 67,601 6.3 0.92% 3.4% 6.0 35% $28.42 143,358 8.1 47,786 8.1 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $30.74 12,719 8.6 4,240 8.6 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $36.99 210,590 9.1 18,530 9.1 1.47% - 1.64% 4.1% 5.5-6.5 27.5% - 35.0% 2017 $23.58 67,322 5.3 67,322 5.3 0.92% 3.4% 6.0 35% $28.42 143,358 7.1 95,572 7.1 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $30.74 12,719 7.6 8,479 7.6 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $36.99 192,060 8.1 64,022 8.1 1.47% - 1.64% 4.1% 5.5-6.5 27.5% - 35.0% 2018 $23.58 53,086 4.3 53,086 4.3 0.92% 3.4% 6.0 35% $28.42 143,358 6.1 143,358 6.1 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $30.74 12,719 6.6 12,719 6.6 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $36.99 192,060 6.8 130,425 6.7 1.47% - 1.64% 4.1% 5.5-6.5 27.5% - 35.0%

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Components of Income Tax Expense (Benefit)	Income tax expense (benefit) for the years ended December 31, 2018 and 2017 as reported in the accompanying Consolidated Statement of Operations was comprised of the following: Year Ended December 31, IN MILLIONS 2018 2017 2016 Current Federal $ 1.0 $ 1.2 $ 0.6 State 2.0 1.8 1.2 Total current expense 3.0 3.0 1.8 Deferred: Federal — — — State — — — Foreign (2.4 ) — — Total deferred (benefit) expense (2.4 ) — — Total income tax expense 0.6 3.0 1.8
Schedule of Effective Income Tax Rate Reconciliation	An income tax expense reconciliation between the U.S. statutory tax rate and the effective tax rate is as follows: Year Ended December 31, IN MILLIONS 2018 2017 2016 Income tax at U.S. federal statutory income tax rate $ 0.4 $ (28.2 ) $ 7.6 State and local taxes, net of federal income tax benefit 2.0 1.8 1.2 Impact of REIT status (2.1 ) 28.6 (7.2 ) Permanent differences (0.1 ) — Foreign tax rate differential 0.2 — Other 0.1 — — Valuation allowance 0.1 0.8 0.2 Income tax (benefit) expense $ 0.6 $ 3.0 $ 1.8
Schedule of Deferred Tax Assets and Liabilities	The components of the Company’s deferred tax assets and liabilities are as follows: Year Ended December 31, IN MILLIONS 2018 2017 Deferred tax assets Net operating loss carryforwards $ 15.1 $ 7.2 Accounts receivable/payable and other 7.4 — Capital leases 1.8 — Total gross deferred tax assets $ 24.3 $ 7.2 Valuation allowance (6.9 ) (7.2 ) Total gross deferred tax assets, net $ 17.4 $ — Deferred tax liabilities Fixed assets (73.5 ) — Intangibles $ (12.8 ) — Total gross deferred tax liabilities $ (86.3 ) — Total net deferred tax assets/(liabilities) $ (68.9 ) —

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases	The future minimum lease payments to be received under non-cancellable operating leases, excluding month-to-month arrangements and metered power reimbursements, for the next five years are shown below: IN MILLIONS 2019 $ 647.6 2020 553.7 2021 453.0 2022 365.5 2023 284.4 Thereafter 835.9 At December 31, 2018 , future minimum lease payments required under operating leases having initial or remaining non-cancellable lease terms in excess of one year are as follows: IN MILLIONS Total 2019 $ 5.0 2020 4.9 2021 3.7 2022 3.7 2023 3.5 Thereafter 43.4 Total $ 64.2

Guarantors (Tables)

Guarantors (Tables)	12 Months Ended
	Dec. 31, 2018
Condensed Financial Information Disclosure [Abstract]
Consolidating Balance Sheet	Consolidating Balance Sheets IN MILLIONS As of December 31, 2018 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Total investment in real estate, net — — — — 3,611.2 644.9 36.9 4,293.0 Cash and cash equivalents — — — — 27.2 37.2 — 64.4 Investment in subsidiaries 2,216.9 22.2 3,122.5 — — — (5,361.6 ) — Rent and other receivables, net — — — — 93.3 12.9 — 106.2 Intercompany receivable 23.2 — 1,761.5 — 6.8 — (1,791.5 ) — Equity investment — — — — — 198.1 — 198.1 Goodwill — — — — 455.1 — — 455.1 Intangible assets, net — — — — 178.1 57.6 — 235.7 Other assets — — 0.5 — 219.8 19.7 — 240.0 Total assets $ 2,240.1 $ 22.2 $ 4,884.5 $ — $ 4,591.5 $ 970.4 $ (7,116.2 ) $ 5,592.5 Debt, net $ — $ — $ 2,624.7 — $ — $ — $ — $ 2,624.7 Intercompany payable — — 23.2 — 1,761.5 6.8 (1,791.5 ) — Capital lease obligations and lease financing arrangements — — — — 104.0 52.7 — 156.7 Accounts payable and accrued expenses — — 19.7 — 95.9 5.7 — 121.3 Construction costs payable — — — — 175.6 19.7 — 195.3 Dividends payable 51.0 — — — — — — 51.0 Deferred revenue and prepaid rents — — — — 144.9 3.7 — 148.6 Deferred tax liability — — — — — 68.9 — 68.9 Total liabilities 51.0 — 2,667.6 — 2,281.9 157.5 (1,791.5 ) 3,366.5 Total stockholders' equity 2,189.1 22.2 2,216.9 — 2,309.6 812.9 (5,324.7 ) 2,226.0 Total liabilities and equity $ 2,240.1 $ 22.2 $ 4,884.5 $ — $ 4,591.5 $ 970.4 $ (7,116.2 ) $ 5,592.5 IN MILLIONS As of December 31, 2017 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Total investment in real estate, net — — — — 3,014.9 25.8 17.7 3,058.4 Cash and cash equivalents — — — — 151.2 0.7 — 151.9 Investment in subsidiaries 1,718.0 17.2 2,190.2 — — — (3,925.4 ) — Rent and other receivables, net — — — — 84.6 2.6 — 87.2 Intercompany receivable 20.0 — 1,656.4 — — — (1,676.4 ) — Equity investment — — — — — 175.6 — 175.6 Goodwill — — — — 455.1 — — 455.1 Intangible assets, net — — — — 203.0 — — 203.0 Other assets — — 0.5 — 177.7 2.7 — 180.9 Total assets $ 1,738.0 $ 17.2 $ 3,847.1 $ — $ 4,086.5 $ 207.4 $ (5,584.1 ) $ 4,312.1 Debt, net $ — $ — $ 2,089.4 — $ — $ — $ — $ 2,089.4 Intercompany payable — — 20.0 — 1,656.4 — (1,676.4 ) — Capital lease obligations and lease financing arrangements — — — — 110.0 32.0 — 142.0 Accounts payable and accrued expenses — — 19.7 — 77.3 0.9 — 97.9 Construction costs payable — — — — 115.5 — — 115.5 Dividends payable 41.8 — — — — — — 41.8 Deferred revenue and prepaid rents — — — — 110.8 0.8 — 111.6 Total liabilities 41.8 — 2,129.1 — 2,070.0 33.7 (1,676.4 ) 2,598.2 Total stockholders' equity 1,696.2 17.2 1,718.0 — 2,016.5 173.7 (3,907.7 ) 1,713.9 Total liabilities and equity $ 1,738.0 $ 17.2 $ 3,847.1 $ — $ 4,086.5 $ 207.4 $ (5,584.1 ) $ 4,312.1
Consolidating Statements of Operations and Comprehensive Income (Loss)	Consolidating Statements of Operations and Comprehensive Income (Loss) IN MILLIONS Year Ended December 31, 2018 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Revenue — — — — 799.7 21.7 — 821.4 Total operating expenses — — — — 700.2 31.5 — 731.7 Operating income — — — — 99.5 (9.8 ) — 89.7 Interest expense — — (110.6 ) — — (3.3 ) 19.2 (94.7 ) Unrealized gain on marketable equity investment — — — — — 9.9 — 9.9 Loss on early extinguishment of debt — — (3.1 ) — — — — (3.1 ) (Loss) income before income taxes — — (113.7 ) — 99.5 (3.2 ) 19.2 1.8 Income tax (expense) benefit — — — — (3.0 ) 2.4 — (0.6 ) Equity (loss) earnings related to investment in subsidiaries (28.9 ) (0.3 ) 84.8 — — — (55.6 ) — Net (loss) income (28.9 ) (0.3 ) (28.9 ) — 96.5 (0.8 ) (36.4 ) 1.2 Other comprehensive loss — — — — — (10.9 ) — (10.9 ) Comprehensive (loss) income $ (28.9 ) $ (0.3 ) $ (28.9 ) $ — $ 96.5 $ (11.7 ) $ (36.4 ) $ (9.7 ) IN MILLIONS Year Ended December 31, 2017 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Revenue — — — — 666.4 5.6 — 672.0 Total operating expenses — — — — 640.4 7.5 — 647.9 Operating income (loss) — — — — 26.0 (1.9 ) — 24.1 Interest expense — — (76.2 ) — — (2.6 ) 10.7 (68.1 ) Loss on early extinguishment of debt — — (36.5 ) — — — — (36.5 ) (Loss) income before income taxes — — (112.7 ) — 26.0 (4.5 ) 10.7 (80.5 ) Income tax expense — — — — (3.0 ) — — (3.0 ) Equity (loss) earnings related to investment in subsidiaries (18.7 ) (0.2 ) 94.0 — (4.6 ) — (70.5 ) — Net (loss) income (18.7 ) (0.2 ) (18.7 ) — 18.4 (4.5 ) (59.8 ) (83.5 ) Other comprehensive income — — — — — 75.5 — 75.5 Comprehensive (loss) income $ (18.7 ) $ (0.2 ) $ (18.7 ) $ — $ 18.4 $ 71.0 $ (59.8 ) $ (8.0 ) IN MILLIONS Year Ended December 31, 2016 Parent (1) General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Revenue — — — — 523.7 5.4 — 529.1 Total operating expenses — — — — 457.5 1.1 — 458.6 Operating income — — — — 66.2 4.3 — 70.5 Interest expense — — (49.1 ) — — (2.8 ) 3.1 (48.8 ) (Loss) income before income taxes — — (49.1 ) — 66.2 1.5 3.1 21.7 Income tax expense — — — — (1.8 ) — — (1.8 ) Equity earnings (loss) related to investment in subsidiaries 15.9 0.2 65.0 — 0.6 — (81.7 ) — Net income (loss) 15.9 0.2 15.9 — 65.0 1.5 (78.6 ) 19.9 Other comprehensive loss — — — — — (0.9 ) — (0.9 ) Comprehensive income (loss) $ 15.9 $ 0.2 $ 15.9 $ — $ 65.0 $ 0.6 $ (78.6 ) $ 19.0
Consolidating Statements of Cash Flows	Consolidating Statements of Cash Flows IN MILLIONS Year Ended December 31, 2018 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Net cash (used in) provided by operating activities — — (103.6 ) — 421.6 (27.9 ) 19.2 $ 309.3 Cash flows from investing activities: Asset acquisitions, primarily real estate, net of cash acquired — — — — — (462.8 ) — (462.8 ) Investment in real estate — — — — (814.6 ) (31.9 ) (19.2 ) (865.7 ) Equity investment — — — — — (12.6 ) — (12.6 ) Investment in subsidiaries (700.0 ) (7.0 ) (829.5 ) — — — 1,536.5 — Return of investment 181.1 — — — — — (181.1 ) — Intercompany borrowings 5.6 — (105.1 ) — (6.8 ) — 106.3 — Net cash (used in) provided by investing activities (513.3 ) (7.0 ) (934.6 ) — (821.4 ) (507.3 ) 1,442.5 (1,341.1 ) Cash flows from financing activities: Issuance of common stock, net 699.6 — — — — — — 699.6 Stock issuance costs — — — — — — — — Dividends paid (181.1 ) — (181.1 ) — — — 181.1 (181.1 ) Intercompany borrowings — — (5.6 ) — 105.1 6.8 (106.3 ) — Proceeds from debt, net — — 1,958.4 — — 29.9 — 1,988.3 Payments on debt — — (1,432.7 ) — — (114.7 ) — (1,547.4 ) Payments on capital lease obligations and lease financing arrangements — — — — (7.9 ) (1.6 ) — (9.5 ) Interest paid by lenders on issuance of the senior notes — — — — — — — — Tax payment upon exercise of equity awards (5.2 ) — — — — — — (5.2 ) Contributions/distributions from parent — 7.0 700.0 — 178.6 650.9 (1,536.5 ) — Net cash provided by (used in) financing activities 513.3 7.0 1,039.0 — 275.8 571.3 (1,461.7 ) 944.7 Effect of exchange rate changes on cash, cash equivalents and restricted cash — — (0.8 ) — — 0.4 — (0.4 ) Net (decrease) increase in cash, cash equivalents and restricted cash — — — — (124.0 ) 36.5 — (87.5 ) Cash, cash equivalents and restricted cash at beginning of period — — — — 151.2 0.7 — 151.9 Cash, cash equivalents and restricted cash at end of period $ — $ — $ — $ — $ 27.2 $ 37.2 $ — $ 64.4 IN MILLIONS Year Ended December 31, 2017 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Net cash (used in) provided by operating activities $ — $ — $ (60.3 ) $ — $ 339.7 $ (0.6 ) $ 10.7 $ 289.5 Cash flows from investing activities: Asset acquisitions, primarily real estate, net of cash acquired — — — — (492.3 ) — — (492.3 ) Investment in real estate — — — — (903.8 ) — (10.7 ) (914.5 ) Equity investment — — — — — (100.0 ) — (100.0 ) Investment in subsidiaries (705.3 ) (7.1 ) (705.3 ) — (0.7 ) — 1,418.4 — Return of investment 145.7 — — — — — (145.7 ) — Intercompany borrowings 6.5 — (598.8 ) — — 0.5 591.8 — Net cash (used in) provided by investing activities (553.1 ) (7.1 ) (1,304.1 ) — (1,396.8 ) (99.5 ) 1,853.8 (1,506.8 ) Cash flows from financing activities: Issuance of common stock, net 705.7 — — — — — — 705.7 Dividends paid (145.7 ) — (145.7 ) — — — 145.7 (145.7 ) Intercompany borrowings — — (6.5 ) — 598.2 — (591.7 ) — Proceeds from debt, net — — 2,558.4 — — — — 2,558.4 Payments on debt — — (1,749.8 ) — — — — (1,749.8 ) Payments on capital lease obligations and lease financing arrangements — — — — (8.6 ) (1.2 ) — (9.8 ) Interest paid by lenders on issuance of the senior notes — — 2.7 — — — — 2.7 Tax payment upon exercise of equity awards (6.9 ) — — — — — — (6.9 ) Contributions/distributions from parent — 7.1 705.3 — 605.3 100.8 (1,418.5 ) — Net cash provided by (used in) financing activities 553.1 7.1 1,364.4 — 1,194.9 99.6 (1,864.5 ) 1,354.6 Net increase (decrease) in cash, cash equivalents and restricted cash — — — — 137.8 (0.5 ) — 137.3 Cash, cash equivalents and restricted cash at beginning of period — — — — 13.4 1.2 — 14.6 Cash, cash equivalents and restricted cash at end of period $ — $ — $ — $ — $ 151.2 $ 0.7 $ — $ 151.9 IN MILLIONS Year Ended December 31, 2016 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Net cash (used in) provided by operating activities $ — $ — $ (45.4 ) $ — $ 221.8 $ — $ 4.2 $ 180.6 Cash flows from investing activities: Asset acquisitions, primarily real estate, net of cash acquired — — — — (131.1 ) — — (131.1 ) Investment in real estate — — — — (598.9 ) (1.1 ) — (600.0 ) Investment in subsidiaries (448.2 ) (4.5 ) (448.2 ) — — — 900.9 — Return of investment 112.3 — — — — — (112.3 ) — Intercompany borrowings 15.3 — (66.3 ) — — (0.5 ) 51.5 — Net cash (used in) provided by investing activities (320.6 ) (4.5 ) (514.5 ) — (730.0 ) (1.6 ) 840.1 (731.1 ) Cash flows from financing activities: Issuance of common stock, net 447.1 — — — — — — 447.1 Dividends paid (112.3 ) — (114.3 ) — — — 112.3 (114.3 ) Intercompany borrowings — — (15.3 ) — 71.0 — (55.7 ) — Proceeds from debt, net — — 701.3 — — — — 701.3 Payments on debt — — (460.0 ) — (1.5 ) — — (461.5 ) Payments on capital lease obligations and lease financing arrangements — — — — (8.0 ) (1.1 ) — (9.1 ) Tax payment upon exercise of equity awards (14.2 ) — — — — — — (14.2 ) Contributions/distributions from parent — 4.5 448.2 — 448.2 — (900.9 ) — Net cash provided by (used in) financing activities 320.6 4.5 559.9 — 509.7 (1.1 ) (844.3 ) 549.3 Net increase (decrease) in cash, cash equivalents and restricted cash — — — — 1.5 (2.7 ) — (1.2 ) Cash, cash equivalents and restricted cash at beginning of period — — — — 11.9 3.9 — 15.8 Cash, cash equivalents and restricted cash at end of period $ — $ — $ — $ — $ 13.4 $ 1.2 $ — $ 14.6

Quarterly Financial Informati_2

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Unaudited Selected Quarterly Financial Information	The table below reflects the unaudited selected quarterly information for the years ended December 31, 2018 and 2017 : IN MILLIONS, except per share amounts 2018 First Quarter Second Quarter Third Quarter Fourth Total Revenue $ 196.6 $ 196.9 $ 206.6 $ 221.3 $ 821.4 Operating income 27.7 27.0 20.2 14.8 89.7 Net income (loss) 43.5 105.9 (42.4 ) (105.8 ) 1.2 Net income (loss) attributed to common shareholders 43.5 105.9 (42.4 ) (105.8 ) 1.2 Basic income (loss) per share 0.45 1.07 (0.43 ) $ (1.09 ) $ — Diluted income (loss) per share 0.45 1.06 (0.43 ) (1.08 ) — IN MILLIONS, except per share amounts 2017 First Second Quarter Third Quarter Fourth Quarter Total Revenue $ 149.3 $ 166.9 $ 175.3 $ 180.5 $ 672.0 Operating income (loss) 19.8 16.7 (36.3 ) 23.9 24.1 Net (loss) income (30.4 ) (0.8 ) (55.1 ) 2.8 (83.5 ) Net (loss) income attributed to common stockholders (30.4 ) (0.8 ) (55.1 ) 2.8 (83.5 ) Basic and diluted (loss) income per share $ (0.36 ) $ (0.01 ) $ (0.61 ) $ 0.03 $ (0.95 )

Description of Business - Narra

Description of Business - Narrative (Details)	12 Months Ended
	Dec. 31, 2018recovery_centerdata_center
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of data operating centers | data_center	48
Number of recovery centers | recovery_center	2

Summary of Significant Accoun_3

Summary of Significant Accounting Policies - Narrative (Details)	3 Months Ended								12 Months Ended
	Dec. 31, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Mar. 31, 2017USD ($)	Dec. 31, 2018USD ($)segment	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Summary Of Significant Accounting Policies [Line Items]
Impairment losses									$ 0	$ 58,000,000	$ 5,000,000
Number of segments | segment									1
Revenue	$ 221,300,000	$ 206,600,000	$ 196,900,000	$ 196,600,000	$ 180,500,000	$ 175,300,000	$ 166,900,000	$ 149,300,000	$ 821,400,000	672,000,000	$ 529,100,000
Total investment in real estate, net	$ 4,293,000,000				$ 3,058,400,000				$ 4,293,000,000	$ 3,058,400,000
Minimum
Summary Of Significant Accounting Policies [Line Items]
Management service contracts, term									1 year
Maximum
Summary Of Significant Accounting Policies [Line Items]
Management service contracts, term									5 years
Microsoft Corporation | Revenue | Customer concentration risk
Summary Of Significant Accounting Policies [Line Items]
Concentration risk percentage									18.00%	19.00%

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Reclassifications (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Construction in progress, including land under development	$ 744.9	$ 487.1
Land held for future development	176.4	63.8
Land	118.5	104.6
Construction costs and other payables	195.3	115.5	$ 132.7
Dividends payable	51	41.8	33.9
Capital lease obligations and lease financing arrangements	156.7	142
Equity investments	198.1	175.6
Accounts payable and accrued expenses	$ 3	29.3	6.9
Restatement Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Construction in progress, including land under development		8.7
Land held for future development		63.8
Land		(72.5)
Premiums and other receivables, net		(3.3)
Construction costs and other payables		115.5
Dividends payable		41.8
Capital lease obligations and lease financing arrangements		131.9
Equity investments		175.6
Accounts payable and accrued expenses		12.3	1.3
Debt issuance costs		19	8.7
Payment of debt extinguishment costs		$ 30.4
Repayment of note payable			$ 8.7

Recently Issued Accounting St_2

Recently Issued Accounting Standards (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit	$ (600.2)	$ (486.9)
Unrealized gain (loss) on marketable equity investment	9.9	0	$ 0
Capitalized internal costs	$ 1.7	$ 0.9
Difference between Revenue Guidance in Effect before and after Topic 606 | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Accumulated deficit				$ 0.3
Accumulated Deficit | Accounting Standards Update 2014-09
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards				0.3
Accumulated Deficit | Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Adoption of accounting standards				$ 75.6

Revenue Recognition - Narrative

Revenue Recognition - Narrative (Details) - USD ($) $ in Millions	Dec. 31, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accumulated deficit	$ (600.2)		$ (486.9)
Revenue recognition, cumulative modified retrospective | Adjustments
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Accumulated deficit		$ 0.3

Revenue Recognition - Disaggreg

Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenue	$ 221.3	$ 206.6	$ 196.9	$ 196.6	$ 180.5	$ 175.3	$ 166.9	$ 149.3	$ 821.4	$ 672	$ 529.1
Lease revenue									787.3	642.9
Colocation rent
Disaggregation of Revenue [Line Items]
Revenue									644.6	539.8
Metered power
Disaggregation of Revenue [Line Items]
Revenue									104	70.2
Interconnection revenue
Disaggregation of Revenue [Line Items]
Revenue									40	34.1
Equipment sales
Disaggregation of Revenue [Line Items]
Revenue									11.9	7.3
Other revenue
Disaggregation of Revenue [Line Items]
Revenue									20.9	20.6
Contracts With Customers
Disaggregation of Revenue [Line Items]
Revenue									$ 34.1	$ 29.1

Acquisitions and Purchase of _3

Acquisitions and Purchase of Fixed Assets - Zenium Topco Ltd. (Details)	Aug. 24, 2018USD ($)data_center	Dec. 31, 2018USD ($)	Mar. 31, 2018USD ($)	Mar. 29, 2018USD ($)	Dec. 31, 2017USD ($)
Zenium Data Centers
Business Acquisition [Line Items]
Number of data center facilities acquired | data_center	4
Consideration for acquisition	$ 462,800,000
Working capital adjustments	1,000,000
Investment in real estate	597,300,000
Cash and cash equivalents	12,700,000
Rent and other receivables	9,000,000
Other assets	1,100,000
Accounts payable	(22,300,000)
Deferred revenue	(3,300,000)
Capital lease obligation	(25,000,000)
Deferred tax liability	(72,700,000)
Debt	(86,300,000)
Net assets acquired attributable to CyrusOne Inc.	475,500,000
Cash acquired	(12,700,000)
Net cash paid at acquisition	462,800,000
Trade name | Zenium Data Centers
Business Acquisition [Line Items]
Intangible assets:	1,800,000
Leasehold interest | Zenium Data Centers
Business Acquisition [Line Items]
Intangible assets:	1,700,000
In-place leases | Zenium Data Centers
Business Acquisition [Line Items]
Intangible assets:	$ 61,500,000
Term Loan
Business Acquisition [Line Items]
Long-term line of credit				$ 174,500,000
2023 Term Loan | Term Loan
Business Acquisition [Line Items]
Line of credit facility, delayed draw feature				300,000,000
Long-term line of credit		$ 1,000,000,000	$ 700,000,000		$ 0
Maximum borrowing capacity				1,000,000,000
Revolving Credit Facility | $1.7 Billion Revolving Credit Facility
Business Acquisition [Line Items]
Long-term line of credit		143,000,000			$ 0
Maximum borrowing capacity		$ 1,700,000,000		$ 1,700,000,000

Acquisitions and Purchase of _4

Acquisitions and Purchase of Fixed Assets - Sentinel Properties (Details) - Sentinel Properties ft² in Thousands, $ in Millions	Feb. 28, 2017USD ($)ft²data_centerMW
Business Acquisition [Line Items]
Number of data center facilities acquired | data_center	2
Consideration for acquisition	$ 492.3
Investment in real estate	420.3
Cash and cash equivalents	3.2
Other assets	2.4
Accounts payable	(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
Business Acquisition [Line Items]
Intangible assets:	2.3
In-place leases
Business Acquisition [Line Items]
Intangible assets:	$ 75.8
Data centers
Business Acquisition [Line Items]
Area acquired (in sqft or acre) | ft²	160
Amount of power capacity acquired | MW	21

Acquisitions and Purchase of _5

Acquisitions and Purchase of Fixed Assets - Land for future development (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)a	Dec. 31, 2017USD ($)a
Business Combinations [Abstract]
Area of land acquired | a	182	209
Payment to acquire property | $	$ 182.3	$ 35.3

Acquisitions and Purchase of _6

Acquisitions and Purchase of Fixed Assets - Real Estate Investments and Intangibles and Related Depreciation and Amortization (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Investment in Real Estate
Building and improvements, cost	$ 1,677.5	$ 1,371.4
Equipment, cost	2,630.2	1,813.9
Building and improvements, accumulated depreciation	(481.8)	(418.2)
Real Estate Investment Property. Accumulated Depreciation, Fixtures And Equipment	(572.7)	(364.2)
Building and improvements, net	1,195.7	953.2
Equipment, net	2,057.5	1,449.7
Intangibles
Cost	402.6	339.1
Less: accumulated depreciation and amortization	(166.9)	(136.1)
Total	235.7	203
Customer relationships
Intangibles
Cost	247.1	247.1
Less: accumulated depreciation and amortization	(137.9)	(123)
Total	109.2	124.1
In-place leases
Intangibles
Cost	136	75.9
Less: accumulated depreciation and amortization	(21.1)	(7.1)
Total	114.9	68.8
Other Contractual
Intangibles
Cost	19.5	16.1
Less: accumulated depreciation and amortization	(7.9)	(6)
Total	$ 11.6	$ 10.1

Investment in Real Estate - Sch

Investment in Real Estate - Schedule of Gross Investment in Real Estate (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Real Estate Properties [Line Items]
Land	$ 118.5	$ 104.6
Building and Improvements	1,677.5	1,371.4
Equipment	2,630.2	1,813.9
Land held for future development	176.4	63.8
Dallas - Carrollton
Real Estate Properties [Line Items]
Land	16.1	16.1
Building and Improvements	62.2	61.8
Equipment	272.5	210.7
Houston - Houston West I
Real Estate Properties [Line Items]
Land	1.4	1.4
Building and Improvements	85.2	85.2
Equipment	51.1	49.8
Northern Virginia - Sterling II
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	28.8	28.8
Equipment	112.4	112.3
San Antonio III
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	40.2	40.3
Equipment	99	96.8
Cincinnati - 7th Street
Real Estate Properties [Line Items]
Land	0.9	0.9
Building and Improvements	114.1	110.6
Equipment	37.4	33.1
Northern Virginia - Sterling V
Real Estate Properties [Line Items]
Land	14.5	14.5
Building and Improvements	80.8	35.7
Equipment	295.8	108.8
Somerset I
Real Estate Properties [Line Items]
Land	12.1	9.3
Building and Improvements	125.8	124.8
Equipment	91	83.7
Dallas - Lewisville
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	76.8	76.7
Equipment	39.6	37.4
Totowa - Madison
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	28.5	28.5
Equipment	57.7	55.1
Chicago - Aurora I
Real Estate Properties [Line Items]
Land	2.4	2.4
Building and Improvements	32.4	32.4
Equipment	132.9	125
Cincinnati - North Cincinnati
Real Estate Properties [Line Items]
Land	0.9	0.9
Building and Improvements	77.9	77.4
Equipment	12.4	9.9
Phoenix - Chandler II
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	16.2	16.2
Equipment	39.4	38.9
Wappingers Falls I
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	11.3	11.3
Equipment	22	18
San Antonio I
Real Estate Properties [Line Items]
Land	4.6	4.6
Building and Improvements	31.7	31.7
Equipment	35.3	34.8
Houston - Houston West II
Real Estate Properties [Line Items]
Land	2.7	2.7
Building and Improvements	22.9	22.8
Equipment	50.9	50.1
Phoenix - Chandler I
Real Estate Properties [Line Items]
Land	10.5	10.5
Building and Improvements	58.3	58.2
Equipment	68.7	65.9
Phoenix - Chandler III
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	11.4	11.4
Equipment	50.8	50
Northern Virginia - Sterling I
Real Estate Properties [Line Items]
Land	6.9	7
Building and Improvements	20.2	20
Equipment	60.4	59.4
Raleigh-Durham I
Real Estate Properties [Line Items]
Land	2.1	2.1
Building and Improvements	79.8	78
Equipment	75.4	76
Houston - Galleria
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	71	68.6
Equipment	20.2	17.6
Phoenix - Chandler VI
Real Estate Properties [Line Items]
Land	2.4	2.4
Building and Improvements	23.3	15.7
Equipment	100.3	49.2
Northern Virginia - Sterling III
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	22.2	22.2
Equipment	61.3	61.3
Frankfurt I
Real Estate Properties [Line Items]
Land	11.2	0
Building and Improvements	125.5	0
Equipment	178.8	0
Austin II
Real Estate Properties [Line Items]
Land	2	2
Building and Improvements	23.4	23.4
Equipment	8.7	7.2
San Antonio II
Real Estate Properties [Line Items]
Land	7	7
Building and Improvements	30.3	29
Equipment	60.8	60.4
Florence
Real Estate Properties [Line Items]
Land	2.2	2.2
Building and Improvements	42	42
Equipment	8.4	5.3
Austin III
Real Estate Properties [Line Items]
Land	3.3	3.3
Building and Improvements	11.7	10.6
Equipment	47	33.9
Phoenix - Chandler IV
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	18.4	18.3
Equipment	43.3	40.9
San Antonio IV
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	42.1	0
Equipment	48.2	17.9
Cincinnati - Hamilton
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	43.7	50.2
Equipment	7.9	6
Northern Virginia - Sterling IV
Real Estate Properties [Line Items]
Land	4.6	4.6
Building and Improvements	20	20
Equipment	76	73.7
Phoenix - Chandler V
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	10.7	5.9
Equipment	53.4	20.5
London II
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	25.2	0
Equipment	74.8	0
London I
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	34.1	0
Equipment	26.3	0
London - Great Bridgewater
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	26.8	28.4
Equipment	1.2	1.1
Cincinnati - Mason
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	20.3	20.3
Equipment	1.7	1.6
Stamford - Riverbend
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	2.9	2.9
Equipment	7.8	6.9
Houston - Houston West III
Real Estate Properties [Line Items]
Land	7.2	7.2
Building and Improvements	18	17.9
Equipment	31.4	30.7
Norwalk I
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	13.6	13.5
Equipment	10.1	9.4
Chicago - Lombard
Real Estate Properties [Line Items]
Land	0.7	0.7
Building and Improvements	4.7	4.7
Equipment	8.1	7.7
Stamford - Omega
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	2.6	2.6
Equipment	0.7	0.7
Cincinnati - Blue Ash
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	0.7	0.7
Equipment	0.2	0.2
Totowa - Commerce
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	4.1	4.1
Equipment	1.7	1.6
South Bend - Crescent
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	1.7	1.7
Equipment	0.2	0.1
South Bend - Monroe
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	2.5	2.5
Equipment	0.4	0.3
Chicago - Aurora II
Real Estate Properties [Line Items]
Land	2.6	2.6
Building and Improvements	22.6	8.3
Equipment	68.6	42.9
Chicago - Aurora Tower
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	4.9	0
Equipment	0.4	0
Dallas - Midway
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	0	2
Equipment	0	0.4
Dallas - Marsh
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	0	0.1
Equipment	0	0.6
Cincinnati - Goldcoast
Real Estate Properties [Line Items]
Land	0.2	0.2
Building and Improvements	4	4
Equipment	0.1	0.1
Northern Virginia - Sterling VI
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	0	0
Equipment	$ 77.5	$ 0

Investment in Real Estate - Nar

Investment in Real Estate - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Real Estate Properties [Line Items]
Construction in progress, land under active development	$ 69,100,000	$ 8,700,000
Cost of construction in progress	744,900,000	487,100,000
Capital expenditures	1,328,500,000	1,406,800,000
Capital expenditures – purchase of fixed assets	462,800,000	492,300,000	$ 131,100,000
Impairment losses	0	58,000,000	$ 5,000,000
Zenium Data Centers
Real Estate Properties [Line Items]
Capital expenditures – purchase of fixed assets	462,800,000
Property for development, Northern Virginia, Phoenix, Dallas, Chicago, San Antonio and Cincinnati; Purchase of land parcels, Allen, Texas and Quincy, Washington
Real Estate Properties [Line Items]
Capital expenditures – purchase of fixed assets	$ 865,700,000	914,500,000
Sentinel Properties
Real Estate Properties [Line Items]
Capital expenditures – purchase of fixed assets		492,300,000
Norwalk I
Real Estate Properties [Line Items]
Impairment losses		54,400,000
Singapore Facility
Real Estate Properties [Line Items]
Impairment losses		$ 3,600,000

Notes Receivable - Narrative (D

Notes Receivable - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	$ 2,100	$ 3,300
Note 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	1,400	1,800
Monthly payments	50
Note 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	300	600
Monthly payments	26
Note 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	0	500
Monthly payments	30
Note 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	300	400
Monthly payments	12
Note 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	100	$ 0
Monthly payments	$ 4

Notes Receivable - Carrying amo

Notes Receivable - Carrying amounts (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	$ 2.1	$ 3.3
Note 1
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	1.4	1.8
Note 2
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	0.3	0.6
Note 3
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	0	0.5
Note 4
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	0.3	0.4
Note 5
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying amount notes receivable	$ 0.1	$ 0

Equity Investment (Details)

Equity Investment (Details) - USD ($) $ / shares in Units, $ in Millions	Oct. 18, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 30, 2018	Oct. 08, 2018	Oct. 17, 2017
Schedule of Equity Method Investments [Line Items]
Equity investments		$ 198.1	$ 175.6
Unrealized gain (loss) on marketable equity investment		$ 9.9	0	$ 0
GDS
Schedule of Equity Method Investments [Line Items]
Newly issued American depository shares (in shares)	8,000,000
Price per ordinary share (in dollars per share)	$ 12.45	$ 23.09
Discount rate	4.00%
Equity investments							$ 100
American depository shares equivalent (in shares)	8
Unrealized gain (loss) on marketable equity investment		$ 9.9
Affiliated Entity | ODATA
Schedule of Equity Method Investments [Line Items]
Investments						$ 11.9
Ownership %						10.00%
Affiliated Entity | ODATA Colombia
Schedule of Equity Method Investments [Line Items]
Investments					$ 0.7
Fair Value | Fair Value, Inputs, Level 1 | GDS
Schedule of Equity Method Investments [Line Items]
Equity investments		$ 185.5	$ 175.6

Goodwill, Intangible and Othe_3

Goodwill, Intangible and Other Long-Lived Assets - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	$ 455,100,000	$ 455,100,000
Impairment of intangible assets	0	0
Impairment of goodwill	0	0
Amortization expense for intangible assets	$ 30,600,000	$ 25,100,000	$ 20,100,000

Goodwill, Intangible and Othe_4

Goodwill, Intangible and Other Long-Lived Assets - Carrying Value of Major Classes of Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 402.6	$ 339.1
Accumulated Amortization	(166.9)	(136.1)
Total	$ 235.7	203
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted- Average Remaining Life (in years)	11 years
Gross Carrying Amount	$ 247.1	247.1
Accumulated Amortization	(137.9)	(123)
Total	$ 109.2	124.1
Trademark/tradename
Finite-Lived Intangible Assets [Line Items]
Weighted- Average Remaining Life (in years)	6 years
Gross Carrying Amount	$ 11.5	9.7
Accumulated Amortization	(6.7)	(5.3)
Total	$ 4.8	4.4
Favorable leasehold interest
Finite-Lived Intangible Assets [Line Items]
Weighted- Average Remaining Life (in years)	36 years
Gross Carrying Amount	$ 5.7	4.1
Accumulated Amortization	(0.7)	(0.5)
Total	$ 5	3.6
In place customer leases
Finite-Lived Intangible Assets [Line Items]
Weighted- Average Remaining Life (in years)	6 years
Gross Carrying Amount	$ 136	75.9
Accumulated Amortization	(21.1)	(7.1)
Total	$ 114.9	68.8
Above and below market leases
Finite-Lived Intangible Assets [Line Items]
Weighted- Average Remaining Life (in years)	7 years
Gross Carrying Amount	$ 2.3	2.3
Accumulated Amortization	(0.5)	(0.2)
Total	$ 1.8	$ 2.1

Goodwill, Intangible and Othe_5

Goodwill, Intangible and Other Long-Lived Assets - Estimated Amortization Expense For Finite-Lived Intangible Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
2,019	$ 40.2
2,020	39
2,021	31.8
2,022	28.5
2,023	20.7
Thereafter	75.5
Total	$ 235.7	$ 203

Other Assets (Details)

Other Assets (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Straight line receivables, net	$ 128.7	$ 100
Deferred leasing and other contract costs	43.6	33.7
Prepaid expenses	26.4	20
Non-real estate assets, net	18.4	16.7
Other	22.9	10.5
Total	$ 240	$ 180.9

Capital Lease Obligations and_3

Capital Lease Obligations and Lease Financing Arrangements - Summary of Capital Lease Obligations and Lease Financing Arrangements (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Leases [Abstract]
Capital lease obligations	$ 33.4	$ 10.1
Lease financing arrangements	123.3	131.9
Total	$ 156.7	$ 142

Debt - Components of Debt (Deta

Debt - Components of Debt (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Mar. 31, 2018	Mar. 29, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Deferred financing costs	$ (32,900,000)			$ (27,900,000)
Total	$ 2,624,700,000			2,089,400,000
Monthly LIBOR	2.53%
$2.0 Billion Credit Facility:
Debt Instrument [Line Items]
Maximum borrowing capacity				2,000,000,000
Term Loan
Debt Instrument [Line Items]
Credit facilities			$ 174,500,000
Term Loan | 2023 Term Loan
Debt Instrument [Line Items]
Credit facilities	$ 1,000,000,000	$ 700,000,000		0
Maximum borrowing capacity			1,000,000,000
Term Loan | 2025 Term Loan
Debt Instrument [Line Items]
Credit facilities	300,000,000			0
Maximum borrowing capacity			300,000,000
Term Loan | 2021 Term Loan
Debt Instrument [Line Items]
Credit facilities	0			250,000,000
Term Loan | 2022 Term Loan
Debt Instrument [Line Items]
Credit facilities	0			650,000,000
2024 Notes and 2027 Notes | 2024 Notes, including bond premium of $5.5 million
Debt Instrument [Line Items]
Long-term debt, gross	$ 705,500,000			706,800,000
Stated interest rate	5.00%
Bond premium	$ 5,500,000
2024 Notes and 2027 Notes | 2027 Notes, including bond premium of $9.1 million
Debt Instrument [Line Items]
Long-term debt, gross	$ 509,100,000			510,500,000
Stated interest rate	5.375%
Bond premium	$ 9,100,000
Revolving Credit Facility | $3.0 Billion Credit Facility:
Debt Instrument [Line Items]
Maximum borrowing capacity	3,000,000,000		3,000,000,000
Revolving Credit Facility | $1.7 Billion Revolving Credit Facility
Debt Instrument [Line Items]
Credit facilities	143,000,000			0
Maximum borrowing capacity	$ 1,700,000,000		$ 1,700,000,000
Term of extension option	1 year
Revolving Credit Facility | $2.0 Billion Credit Facility:
Debt Instrument [Line Items]
Credit facilities				900,000,000
Revolving Credit Facility | $1.1 Billion Revolving Credit Facility
Debt Instrument [Line Items]
Credit facilities	$ 0			0
Maximum borrowing capacity	$ 1,100,000,000			$ 1,100,000,000
LIBOR | Term Loan | 2023 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate	1.40%
LIBOR | Term Loan | 2025 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate	1.70%
LIBOR | Term Loan | 2021 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%
LIBOR | Term Loan | 2022 Term Loan
Debt Instrument [Line Items]
Basis spread on variable rate	1.50%
LIBOR | Revolving Credit Facility | $1.7 Billion Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate	1.45%
LIBOR | Revolving Credit Facility | $1.1 Billion Revolving Credit Facility
Debt Instrument [Line Items]
Basis spread on variable rate	1.55%

Capital Lease Obligations and_4

Capital Lease Obligations and Lease Financing Arrangements - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)data_center	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Leases [Abstract]
Number of data center facilities under capital leases | data_center	5
Interest expense on capital lease obligations | $	$ 9	$ 9	$ 10.6

Debt - Narrative (Details)

Debt - Narrative (Details)

Mar. 29, 2018USD ($)tranche

Nov. 03, 2017USD ($)

Mar. 17, 2017USD ($)

Aug. 31, 2018EUR (€)

Mar. 31, 2017USD ($)

Sep. 30, 2018USD ($)

Dec. 31, 2018USD ($)

Dec. 31, 2017USD ($)

Dec. 31, 2016USD ($)

Mar. 31, 2018USD ($)

Mar. 30, 2017USD ($)

Feb. 28, 2017USD ($)

Nov. 20, 2012USD ($)

Debt Instrument [Line Items]

Deferred financing costs

$ 32,900,000

$ 27,900,000

Letters of credit outstanding

8,000,000

Cash and cash equivalents

64,400,000

151,900,000

Loss on early extinguishment of debt

(3,100,000)

(36,500,000)

$ 0

Debt, net

2,624,700,000

$ 2,089,400,000

$3.0 Billion Credit Facility:

Debt Instrument [Line Items]

Credit facility, available capacity under accordion feature

$ 4,000,000,000

2021 Term Loan

Debt Instrument [Line Items]

Debt instrument, term

5 years

2022 Term Loan

Debt Instrument [Line Items]

Debt instrument, term

7 years

EUR Construction Facility

Debt Instrument [Line Items]

Debt instrument, term

6 years

Face amount of debt | €

€ 100,000,000

2023 Term Loan

Debt Instrument [Line Items]

Debt instrument, term

5 years

2025 Term Loan

Debt Instrument [Line Items]

Debt instrument, term

7 years

$2.0 Billion Credit Facility:

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 2,000,000,000

Term Loan

Debt Instrument [Line Items]

Long-term line of credit

$ 174,500,000

Term Loan | 2021 Term Loan

Debt Instrument [Line Items]

Long-term line of credit

0

250,000,000

Term Loan | 2022 Term Loan

Debt Instrument [Line Items]

Long-term line of credit

0

650,000,000

Term Loan | 2023 Term Loan

Debt Instrument [Line Items]

Maximum borrowing capacity

1,000,000,000

Long-term line of credit

1,000,000,000

0

$ 700,000,000

Line of credit facility, delayed draw feature

$ 300,000,000

Delayed draw feature, period

6 months

Delayed draw feature, number of tranches | tranche

3

Term Loan | 2025 Term Loan

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 300,000,000

Long-term line of credit

$ 300,000,000

0

2024 Notes and 2027 Notes | 5.000% Senior Notes Due 2024 and 5.375% Senior Notes Due 2027

Debt Instrument [Line Items]

Debt proceeds, net of underwriting costs

$ 416,100,000

$ 791,200,000

Debt underwriting costs

4,400,000

2024 Notes and 2027 Notes | 5.000% senior notes due 2024

Debt Instrument [Line Items]

Stated interest rate

5.00%

2024 Notes and 2027 Notes | 5.000% senior notes due 2024 | CyrusOne LP and CyrusOne Finance Corp

Debt Instrument [Line Items]

Face amount of debt

200,000,000

500,000,000

2024 Notes and 2027 Notes | 5.375% senior notes due 2027

Debt Instrument [Line Items]

Stated interest rate

5.375%

2024 Notes and 2027 Notes | 5.375% senior notes due 2027 | CyrusOne LP and CyrusOne Finance Corp

Debt Instrument [Line Items]

Face amount of debt

$ 200,000,000

$ 300,000,000

2024 Notes and 2027 Notes | 6.375% senior notes due 2022

Debt Instrument [Line Items]

Debt, net

$ 474,800,000

$ 469,000,000

Repurchase amount

$ 515,100,000

Repurchase amount, accrued and unpaid interest

10,300,000

Loss on extinguishment of debt

$ 36,200,000

2024 Notes and 2027 Notes | 6.375% senior notes due 2022 | CyrusOne LP and CyrusOne Finance Corp

Debt Instrument [Line Items]

Debt, net

$ 525,000,000

Stated interest rate

6.375%

Revolving Credit Facility | $3.0 Billion Credit Facility:

Debt Instrument [Line Items]

Maximum borrowing capacity

3,000,000,000

$ 3,000,000,000

Remaining borrowing capacity

1,549,000,000

Amount used to retire debt

1,000,000,000

Revolving Credit Facility | Second Amended and Restated Credit Agreement

Debt Instrument [Line Items]

Commitment fee amount

3,800,000

1,900,000

$ 1,600,000

Revolving Credit Facility | $1.7 Billion Revolving Credit Facility

Debt Instrument [Line Items]

Maximum borrowing capacity

1,700,000,000

1,700,000,000

Multicurrency sublimit

$ 750,000,000

Long-term line of credit

$ 143,000,000

0

Option to extend maturity term

1 year

Commitment fee percent

0.25%

Commitment fee percentage, rate upon 50% or greater utilization

0.15%

Revolving Credit Facility | $2.0 Billion Credit Facility:

Debt Instrument [Line Items]

Long-term line of credit

900,000,000

Loss on early extinguishment of debt

$ 3,100,000

Revolving Credit Facility | $1.1 Billion Revolving Credit Facility

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 1,100,000,000

1,100,000,000

Long-term line of credit

$ 0

$ 0

Capital Lease Obligations and_5

Capital Lease Obligations and Lease Financing Arrangements - Capital Lease Obligations (Details) $ in Millions	Dec. 31, 2018USD ($)
Capital Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,019	$ 2.7
2,020	2.8
2,021	2.9
2,022	2
2,023	1
Thereafter	22
Total	33.4
Capital Leases
Interest
2,019	1.7
2,020	1.5
2,021	1.3
2,022	1.1
2,023	0.9
Thereafter	$ 9.3

Debt - Maturities of Debt (Deta

Debt - Maturities of Debt (Details) $ in Millions	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
2,019	$ 0
2,020	0
2,021	0
2,022	0
2,023	1,143
Thereafter	1,500
Total debt	2,643
$3.0 Billion Credit Facility
Debt Instrument [Line Items]
2,019	0
2,020	0
2,021	0
2,022	0
2,023	1,143
Thereafter	300
Total debt	1,443
2024 Notes and 2027 Notes
Debt Instrument [Line Items]
2,019	0
2,020	0
2,021	0
2,022	0
2,023	0
Thereafter	1,200
Total debt	$ 1,200

Capital Lease Obligations and_6

Capital Lease Obligations and Lease Financing Arrangements - Lease Financing Arrangements (Details) $ in Millions	Dec. 31, 2018USD ($)
Future Value of Payments
2,019	$ 2.7
2,020	2.8
2,021	2.9
2,022	2
2,023	1
Thereafter	22
Total	33.4
Lease Financing Arrangements
Future Value of Payments
2,019	15
2,020	27.6
2,021	11.4
2,022	11.6
2,023	10
Thereafter	89.1
Total	164.7
Interest
2,019	7.3
2,020	6.6
2,021	5.7
2,022	5.4
2,023	4.1
Thereafter	12.3
Total lease financing arrangements	41.4
2,019	7.7
2,020	21
2,021	5.7
2,022	6.2
2,023	5.9
Thereafter	76.8
Total lease financing arrangements	$ 123.3

Fair Value of Financial Instr_3

Fair Value of Financial Instruments - Carrying and Fair Value (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 17, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 2,624,700,000	$ 2,089,400,000
GDS Equity investment	198,100,000	175,600,000
Impairment losses	0	58,000,000	$ 5,000,000
Senior Notes | Carrying Value | 2024 Notes, including bond premium
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt		706,800,000
Senior Notes | Carrying Value | 2027 Notes, including bond premium
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt		510,500,000
Fair Value, Inputs, Level 1 | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
GDS Equity investment	198,100,000
Fair Value, Inputs, Level 1 | Senior Notes | Fair Value | 2024 Notes, including bond premium
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	684,100,000	728,000,000
Fair Value, Inputs, Level 1 | Senior Notes | Fair Value | 2027 Notes, including bond premium
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	488,000,000	527,500,000
GDS
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
GDS Equity investment				$ 100,000,000
GDS | Carrying Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
GDS Equity investment		175,600,000
GDS | Fair Value, Inputs, Level 1 | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
GDS Equity investment	$ 185,500,000	$ 175,600,000

Dividends (Details)

Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 20, 2019	Jan. 11, 2019	Oct. 12, 2018	Jul. 13, 2018	Apr. 13, 2018	Jan. 12, 2018	Oct. 13, 2017	Jul. 14, 2017	Apr. 14, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Dividends Payable [Line Items]
Cash dividend per share or operating partnership unit (in dollars per share)			$ 0.46	$ 0.46	$ 0.46	$ 0.42	$ 0.42	$ 0.42	$ 0.42
Dividends payable										$ 51	$ 41.8	$ 33.9
Dividends declared per share (in dollars per share)										$ 1.84	$ 1.68	$ 1.52
Subsequent event
Dividends Payable [Line Items]
Cash dividend per share or operating partnership unit (in dollars per share)		$ 0.46
Dividends declared per share (in dollars per share)	$ 0.46

Customer Leases (Details)

Customer Leases (Details) $ in Millions	Dec. 31, 2018USD ($)
Leases [Abstract]
2,019	$ 647.6
2,020	553.7
2,021	453
2,022	365.5
2,023	284.4
Thereafter	$ 835.9

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Retirement Benefits [Abstract]
Health care plans expenses	$ 3.3	$ 2.7	$ 4.4
Retirement savings plan matching contributions	$ 1.8	$ 1.5	$ 1.5

Income (Loss) per Share - Narra

Income (Loss) per Share - Narrative (Details) - USD ($) shares in Millions, $ in Millions	Dec. 28, 2018	Sep. 28, 2018	Aug. 15, 2016	Aug. 10, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Formation [Line Items]
Issuance of common stock (in shares)					12.2	12.8
Proceeds from public stock offerings					$ 699.6	$ 705.7	$ 447.1
Stock issuance costs					$ 0
Public stock offering
Business Formation [Line Items]
Issuance of common stock (in shares)		6.7	3.4
Proceeds from public stock offerings		$ 397.3	$ 164.8
Stock issuance costs		$ 18.1	$ 6.9
Stock issued upon underwriters exercising option to purchase additional shares
Business Formation [Line Items]
Issuance of common stock (in shares)		2.5		1
Morgan Stanley & Co, LLC | Stock issued upon underwriters exercising option to purchase additional shares
Business Formation [Line Items]
Issuance of common stock, net	$ 148.2

Income (Loss) per Share - Compu

Income (Loss) per Share - Computation of Basic and Diluted Net (Loss) Income Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Numerator:
Net income (loss)	$ (105.8)	$ (42.4)	$ 105.9	$ 43.5	$ 2.8	$ (55.1)	$ (0.8)	$ (30.4)	$ 1.2	$ (83.5)	$ 19.9
Less: Restricted stock dividends, Basic									(1.1)	(0.9)	(0.7)
Less: Restricted stock dividends, Diluted									(1.1)	(0.9)	(0.7)
Net (loss) income available to stockholders, Basic									0.1	(84.4)	19.2
Net (loss) income available to stockholders, Diluted									$ 0.1	$ (84.4)	$ 19.2
Denominator:
Weighted average common outstanding - basic (in shares)									99.8	88.9	78.3
Performance-based restricted stock and units (in shares)									0.6	0	0.7
Weighted average shares outstanding- diluted (in shares)									100.4	88.9	79
EPS:
Net (loss) income per share- basic (in dollars per share)	$ (1.09)	$ (0.43)	$ 1.07	$ 0.45					$ 0	$ (0.95)	$ 0.24
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Net (loss) income per share - diluted (in dollars per share)	$ (1.08)	$ (0.43)	$ 1.06	$ 0.45					$ 0	$ (0.95)	$ 0.24
Restricted Stock
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Anti-dilutive securities excluded from diluted earnings per share (in shares)										0.4
Stock options
Dilutive Securities, Effect on Basic Earnings Per Share [Abstract]
Anti-dilutive securities excluded from diluted earnings per share (in shares)										0.1

Stockholders' Equity - Narrativ

Stockholders' Equity - Narrative (Details)

Feb. 26, 2018$ / sharesshares

Feb. 13, 2017$ / sharesshares

Feb. 01, 2016$ / sharesshares

Feb. 10, 2015

Feb. 07, 2014

Apr. 17, 2013$ / shares

Jan. 24, 2013USD ($)shares

Dec. 31, 2018USD ($)$ / sharesshares

Dec. 31, 2017USD ($)$ / sharesshares

Dec. 31, 2016USD ($)executiveshares

Dec. 31, 2015USD ($)shares

Dec. 31, 2014USD ($)shares

Dec. 31, 2013USD ($)

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

Issuance of common stock (in shares)

12,200,000

12,800,000

Shares issued, price per share (in dollars per share) | $ / shares

$ 59.28

$ 56.10

Common stock outstanding (in shares)

108,329,314

96,137,874

Grant date fair value (in dollars per share) | $ / shares

$ 0

Outstanding options (in shares)

401,223

415,459

434,268

Intrinsic vale of options exercised | $

$ 600,000

$ 500,000

$ 1,300,000

Intrinsic value of options outstanding | $

8,700,000

Intrinsic value of options exercisable | $

7,700,000

2013 Grants

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

Total awards grant date fair value | $

$ 25,400,000

Unrecognized compensation expense, other than options | $

0

2014 Grants

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

Total awards grant date fair value | $

$ 12,900,000

Unrecognized compensation expense, other than options | $

0

2015 Grants

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

Total awards grant date fair value | $

$ 13,800,000

Unrecognized compensation expense, other than options | $

0

2016 Grants

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

Total awards grant date fair value | $

$ 22,600,000

Unrecognized compensation expense, other than options | $

$ 1,000,000

Unrecognized compensation expense, period for recognition

1 month 6 days

2017 Grants

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

Cap on award vesting in first two years

100.00%

Total awards grant date fair value | $

$ 15,900,000

Unrecognized compensation expense, other than options | $

$ 4,300,000

Unrecognized compensation expense, period for recognition

10 months 24 days

2018 Grants

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

Total awards grant date fair value | $

$ 20,200,000

Unrecognized compensation expense, other than options | $

$ 12,500,000

Unrecognized compensation expense, period for recognition

1 year 8 months 12 days

Restricted stock

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

Grants in period (in shares)

17,052

Granted (in dollars per share) | $ / shares

$ 51.31

Non-vested balance (in shares)

419,356

715,098

1,274,713

Restricted stock | 2014 Grants

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

Award vesting period

3 years

Grants in period (in shares)

46,313

Other than options grant date value | $

$ 1,000,000

Restricted stock | 2014 Grants | Cliff Vesting

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

Award vesting period

1 year

Restricted stock | 2015 Grants

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

Award vesting period

3 years

Award vesting rights percentage

20.00%

Grants in period (in shares)

50,300

Restricted stock | 2016 Grants

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

Award vesting period

3 years

3 years

Grants in period (in shares)

47,667

Restricted stock | 2016 Grants | Cliff Vesting

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

Award vesting period

3 years

Grants in period (in shares)

5,894

Restricted stock | 2017 Grants

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

Award vesting period

1 year

Grants in period (in shares)

18,179

Restricted stock | 2018 Grants

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

Award vesting period

1 year

Grants in period (in shares)

17,052

Time, performance, and market-based awards | 2016 Grants

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

Grants in period (in shares)

641,097

Performance and market-based awards | 2015 Grants

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

Award vesting period

3 years

Cap on award vesting in first two years

100.00%

Award vesting rights percentage

80.00%

True-up cap on award vesting for year three

200.00%

Performance and market-based awards | 2016 Grants

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

Award vesting period

3 years

Cap on award vesting in first two years

100.00%

True-up cap on award vesting for year three

200.00%

Performance awards | 2013 Grants

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

Award vesting period

3 years

Award vesting rights percentage

50.00%

Performance awards | 2014 Grants

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

Award vesting rights percentage

50.00%

Performance awards | 2014 Grants | Below 90% of EBITDA Target

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

Award vesting rights percentage

0.00%

Performance awards | 2014 Grants | At 90% of EBITDA Target

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

Award vesting rights percentage

50.00%

Performance awards | 2014 Grants | At 100% of EBITDA Target

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

Award vesting rights percentage

100.00%

Performance awards | 2014 Grants | At or above 115% of EBITDA Target

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

Award vesting rights percentage

200.00%

Performance awards | 2015 Grants

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

Grants in period (in shares)

67,012

Performance awards | 2015 Grants | Cliff Vesting

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

Award vesting period

3 years

Time and performance based, restricted stock | 2016 Grants

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

Granted (in dollars per share) | $ / shares

$ 36.99

Market-based restricted stock

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

Award vesting period

3 years

Market-based restricted stock | If CyrusOne's total stockholder return is less than the return of the Index

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

Award vesting rights percentage

0.00%

Market-based restricted stock | If CyrusOne's total stockholder return is equal to or greater than the return of the Index

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

Award vesting rights percentage

100.00%

Market-based restricted stock | if CyrusOne's total stockholder return exceeds the return of the Index by 2%

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

Award vesting rights percentage

200.00%

Market-based restricted stock | If CyrusOne's total stockholder return exceeds the return of the Index, but is negative

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

Award vesting rights percentage

50.00%

Market-based restricted stock | 2013 Grants

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

Award vesting rights percentage

50.00%

Market-based restricted stock | 2014 Grants

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

Award vesting period

3 years

Award vesting rights percentage

50.00%

Market-based restricted stock | 2016 Grants

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

Granted (in dollars per share) | $ / shares

$ 43.66

Market-based restricted stock | 2017 Grants

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

Grants in period (in shares)

129,146

Granted (in dollars per share) | $ / shares

$ 63.23

Market-based restricted stock | 2018 Grants

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

Grants in period (in shares)

160,266

Granted (in dollars per share) | $ / shares

$ 52.53

Time-based restricted stock units and restricted stock | 2017 Grants

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

Granted (in dollars per share) | $ / shares

$ 48.13

Time-based restricted stock units and restricted stock | 2018 Grants

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

Granted (in dollars per share) | $ / shares

$ 51.31

Time-based restricted units

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

Term of dividends payable

10 days

Time-based restricted units | 2016 Grants | Cliff Vesting

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

Award vesting period

3 years

Time-based restricted units | 2017 Grants

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

Award vesting period

3 years

3 years

Grants in period (in shares)

119,218

20,852

Time-based restricted units | 2018 Grants

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

Award vesting period

3 years

3 years

Grants in period (in shares)

161,797

40,249

Stock options | 2013 Grants

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

Expiration period for award

10 years

Weighted average exercise price for options granted (in dollars per share) | $ / shares

$ 23.58

Stock options | 2015 Grants

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

Award vesting period

3 years

Stock options | 2016 Grants

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

Award vesting period

3 years

Grants in period (in shares)

222,461

Expiration period for award

10 years

Weighted average exercise price for options granted (in dollars per share) | $ / shares

$ 36.99

Grant date fair value (in dollars per share) | $ / shares

$ 6.99

Senior executives

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

Accelerated compensation cost | $

$ 800,000

$ 2,400,000

Number of individuals with accelerated vesting | executive

2

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

2012 LTIP Plan

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

Shares authorized (in shares)

8,900,000

Shares available for grant (in shares)

5,100,000

Minimum | 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 | 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%

Stockholders' Equity - Allocate

Stockholders' Equity - Allocated Share-based Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	$ 17.5	$ 14.7	$ 12.3
2013 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	0	0	0.1
2014 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	0	0.1	1.2
2015 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	0.4	1.8	3.5
2016 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	5.7	6.6	7.2
2017 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	4.6	6.2	0
2018 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	6.8	0	0
Founders
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	$ 0	$ 0	$ 0.3

Stockholders' Equity - Other Th

Stockholders' Equity - Other Than Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restricted Stock Units
Restricted Stock Units
Non-vested beginning balance (in shares)	265,002	0
Granted (in shares)	362,312
Vested (in shares)	(88,425)
Forfeited (in shares)	(27,480)
Non-vested ending balance (in shares)	511,409	265,002
Weighted Average Grant Date Fair Value
Non-vested beginning balance (in dollars per share)	$ 56.08
Granted (in dollars per share)	53.23
Vested (in dollars per share)	44.52
Forfeited (in dollars per share)	52.97
Non-vested ending balance (in dollars per share)	$ 56.23	$ 56.08
Restricted Stock
Restricted Stock Units
Non-vested beginning balance (in shares)	715,098	1,274,713
Granted (in shares)	17,052
Vested (in shares)	(253,015)
Forfeited (in shares)	(59,779)
Non-vested ending balance (in shares)	419,356	715,098
Weighted Average Grant Date Fair Value
Non-vested beginning balance (in dollars per share)	$ 32.21
Granted (in dollars per share)	51.31
Vested (in dollars per share)	28.25
Forfeited (in dollars per share)	29.69
Non-vested ending balance (in dollars per share)	$ 35.73	$ 32.21

Stockholders' Equity - Options

Stockholders' Equity - Options (Details)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Options
Beginning balance (in shares) | shares	415,459
Granted (in shares) | shares	0
Exercised (in shares) | shares	(14,236)
Forfeited or expired (in shares) | shares	0
Ending balance (in shares) | shares	401,223
Exercisable (in shares) | shares	339,588
Vested and expected to vest (in shares) | shares	401,223
Weighted Average Exercise Price
Beginning balance (in dollars per share) | $ / shares	$ 31.67
Granted (in dollars per share) | $ / shares	0
Exercised (in dollars per share) | $ / shares	23.58
Forfeited or expired (in dollars per share) | $ / shares	0
Ending balance (in dollars per share) | $ / shares	31.96
Exercisable (in dollars per share) | $ / shares	31.04
Vested and expected to vest (in dollars per share) | $ / shares	$ 31.96

Stockholders' Equity - Option V

Stockholders' Equity - Option Valuation Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares (in shares)	401,223	415,459	434,268
Exercisable (in shares)	339,588
$ 23.58
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in dollars per share)	$ 23.58	$ 23.58	$ 23.58
Number of shares (in shares)	53,086	67,322	67,601
Weighted average outstanding contractual term (in years)	4 years 3 months 18 days	5 years 3 months 18 days	6 years 3 months 18 days
Exercisable (in shares)	53,086	67,322	67,601
Weighted average exercisable contractual term (in years)	4 years 3 months 18 days	5 years 3 months 18 days	6 years 3 months 18 days
Risk-free rate	0.92%	0.92%	0.92%
Expected annual dividend	3.40%	3.40%	3.40%
Expected term (in years)	6 years	6 years	6 years
Expected volatility	35.00%	35.00%	35.00%
$ 28.42
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in dollars per share)	$ 28.42	$ 28.42	$ 28.42
Number of shares (in shares)	143,358	143,358	143,358
Weighted average outstanding contractual term (in years)	6 years 1 month 6 days	7 years 1 month 6 days	8 years 1 month 6 days
Exercisable (in shares)	143,358	95,572	47,786
Weighted average exercisable contractual term (in years)	6 years 1 month 6 days	7 years 1 month 6 days	8 years 1 month 6 days
Expected annual dividend	4.40%	4.40%	4.40%
$ 30.74
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in dollars per share)	$ 30.74	$ 30.74	$ 30.74
Number of shares (in shares)	12,719	12,719	12,719
Weighted average outstanding contractual term (in years)	6 years 7 months 6 days	7 years 7 months 6 days	8 years 7 months 6 days
Exercisable (in shares)	12,719	8,479	4,240
Weighted average exercisable contractual term (in years)	6 years 7 months 6 days	7 years 7 months 6 days	8 years 7 months 6 days
Expected annual dividend	4.40%	4.40%	4.40%
$ 36.99
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in dollars per share)	$ 36.99	$ 36.99	$ 36.99
Number of shares (in shares)	192,060	192,060	210,590
Weighted average outstanding contractual term (in years)	6 years 9 months 18 days	8 years 1 month 6 days	9 years 1 month 6 days
Exercisable (in shares)	130,425	64,022	18,530
Weighted average exercisable contractual term (in years)	6 years 8 months 12 days	8 years 1 month 6 days	9 years 1 month 6 days
Expected annual dividend	4.10%	4.10%	4.10%
Minimum | $28.42
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.60%	1.60%	1.60%
Expected term (in years)	5 years 6 months	5 years 6 months	5 years 6 months
Expected volatility	32.50%	32.50%	32.50%
Minimum | $30.74
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.60%	1.60%	1.60%
Expected term (in years)	5 years 6 months	5 years 6 months	5 years 6 months
Expected volatility	32.50%	32.50%	32.50%
Minimum | $36.99
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.47%	1.47%	1.47%
Expected term (in years)	5 years 6 months	5 years 6 months	5 years 6 months
Expected volatility	27.50%	27.50%	27.50%
Maximum | $28.42
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.75%	1.75%	1.75%
Expected term (in years)	6 years 6 months	6 years 6 months	6 years 6 months
Expected volatility	37.50%	37.50%	37.50%
Maximum | $30.74
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.75%	1.75%	1.75%
Expected term (in years)	6 years 6 months	6 years 6 months	6 years 6 months
Expected volatility	37.50%	37.50%	37.50%
Maximum | $36.99
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.64%	1.64%	1.64%
Expected term (in years)	6 years 6 months	6 years 6 months	6 years 6 months
Expected volatility	35.00%	35.00%	35.00%

Related Party Transactions (De

Related Party Transactions (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
GDS Holdings Limited | Investee
Related Party Transaction [Line Items]
Commission and referral charges and accrued expenses	$ 0.9
ODATA | Affiliated Entity
Related Party Transaction [Line Items]
Ownership %	10.00%

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Aug. 24, 2018
Income Taxes [Line Items]
Income tax expense	$ 600,000	$ 3,000,000	$ 1,800,000
Net deferred tax assets		0
Deferred tax liability	68,900,000	0
Valuation allowance	$ 6,900,000	$ 7,200,000
Minimum
Income Taxes [Line Items]
Percentage of distributed taxable income to qualify as a REIT	90.00%
Maximum
Income Taxes [Line Items]
Percentage of distributed taxable income to qualify as a REIT	100.00%
Zenium Data Centers
Income Taxes [Line Items]
Deferred tax liability				$ 72,700,000

Income Taxes - Component of Inc

Income Taxes - Component of Income Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current
Federal	$ 1	$ 1.2	$ 0.6
State	2	1.8	1.2
Total current tax expense (benefit)	3	3	1.8
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	(2.4)	0	0
Total deferred tax expense (benefit)	(2.4)	0	0
Income Tax Expense (Benefit)	$ 0.6	$ 3	$ 1.8

Income Taxes - Effective Income

Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income tax at U.S. federal statutory income tax rate	$ 0.4	$ (28.2)	$ 7.6
State and local taxes, net of federal income tax benefit	2	1.8	1.2
Impact of REIT status	(2.1)	28.6	(7.2)
Permanent differences	(0.1)	0
Foreign tax rate differential	0.2	0
Other	0.1	0	0
Other	0.1	0.8	0.2
Income Tax Expense (Benefit)	$ 0.6	$ 3	$ 1.8

Income Taxes - Components of De

Income Taxes - Components of Deferred Tax Assets and LIabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets
Net operating loss carryforwards	$ 15.1	$ 7.2
Accounts receivable/payable and other	7.4	0
Capital leases	1.8	0
Total gross deferred tax assets	24.3	7.2
Valuation allowance	(6.9)	(7.2)
Total gross deferred tax assets, net	17.4	0
Deferred tax liabilities
Fixed assets	(73.5)	0
Intangibles	(12.8)	0
Total gross deferred tax liabilities	(86.3)	0
Total net deferred tax liabilities	$ (68.9)	$ 0

Commitments and Contingencies -

Commitments and Contingencies - Narrative (Details) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Rent expense		$ 6,600,000	$ 8,200,000	$ 7,500,000
Letters of credit outstanding		8,000,000
Performance Guarantee
Loss Contingencies [Line Items]
Loss contingency accrual		0	$ 0
Data Center Facilities And Equipment
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Amount of minimum purchase commitment		281,900,000
Data Center Facilities And Equipment | Minimum
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Term of purchase commitment	1 year
Data Center Facilities And Equipment | Maximum
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Term of purchase commitment	2 years
Services
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Amount of minimum purchase commitment		$ 45,400,000
Services | Minimum
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Term of purchase commitment		1 year
Services | Maximum
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Term of purchase commitment		2 years

Commitments and Contingencies_2

Commitments and Contingencies - Operating Leases (Details) $ in Millions	Dec. 31, 2018USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,019	$ 5
2,020	4.9
2,021	3.7
2,022	3.7
2,023	3.5
Thereafter	43.4
Total	$ 64.2

Guarantors - Narrative (Details

Guarantors - Narrative (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 17, 2017
Condensed Financial Statements, Captions [Line Items]
Minimum unencumbered asset value percentage of unsecured debt	150.00%
Gross operating real estate included in guarantor subsidiaries	85.00%
GDS Equity investment		$ 198.1	$ 175.6
Unrealized gain on marketable equity investment		9.9	0	$ 0
Non- Guarantors
Condensed Financial Statements, Captions [Line Items]
GDS Equity investment		198.1	175.6
Unrealized gain on marketable equity investment		9.9
GDS
Condensed Financial Statements, Captions [Line Items]
GDS Equity investment					$ 100
Unrealized gain on marketable equity investment		9.9
GDS | Non- Guarantors
Condensed Financial Statements, Captions [Line Items]
GDS Equity investment		$ 185.5	$ 175.6

Guarantors - Consolidating Bala

Guarantors - Consolidating Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Consolidating Balance Sheets
Total investment in real estate, net	$ 4,293	$ 3,058.4
Cash and cash equivalents	64.4	151.9
Investment in subsidiaries	0	0
Rent and other receivables, net	106.2	87.2
Intercompany receivable	0	0
GDS Equity investment	198.1	175.6
Goodwill	455.1	455.1
Intangible assets, net	235.7	203
Other assets	240	180.9
Total assets	5,592.5	4,312.1
Debt, net	2,624.7	2,089.4
Intercompany payable	0	0
Capital lease obligations and lease financing arrangements	156.7	142
Accounts payable and accrued expenses	121.3	97.9
Construction costs payable	195.3	115.5	$ 132.7
Dividends payable	51	41.8	$ 33.9
Deferred revenue and prepaid rents	148.6	111.6
Deferred tax liability	68.9	0
Total liabilities	3,366.5	2,598.2
Total stockholders’ equity	2,226	1,713.9
Total liabilities and equity	5,592.5	4,312.1
Eliminations/Consolidations
Condensed Consolidating Balance Sheets
Total investment in real estate, net	36.9	17.7
Cash and cash equivalents	0	0
Investment in subsidiaries	(5,361.6)	(3,925.4)
Rent and other receivables, net	0	0
Intercompany receivable	(1,791.5)	(1,676.4)
GDS Equity investment	0	0
Goodwill	0	0
Intangible assets, net	0	0
Other assets	0	0
Total assets	(7,116.2)	(5,584.1)
Debt, net	0	0
Intercompany payable	(1,791.5)	(1,676.4)
Capital lease obligations and lease financing arrangements	0	0
Accounts payable and accrued expenses	0	0
Construction costs payable	0	0
Dividends payable	0	0
Deferred revenue and prepaid rents	0	0
Deferred tax liability	0
Total liabilities	(1,791.5)	(1,676.4)
Total stockholders’ equity	(5,324.7)	(3,907.7)
Total liabilities and equity	(7,116.2)	(5,584.1)
General Partner
Condensed Consolidating Balance Sheets
Total investment in real estate, net	0	0
Cash and cash equivalents	0	0
Investment in subsidiaries	22.2	17.2
Rent and other receivables, net	0	0
Intercompany receivable	0	0
GDS Equity investment	0	0
Goodwill	0	0
Intangible assets, net	0	0
Other assets	0	0
Total assets	22.2	17.2
Debt, net	0	0
Intercompany payable	0	0
Capital lease obligations and lease financing arrangements	0	0
Accounts payable and accrued expenses	0	0
Construction costs payable	0	0
Dividends payable	0	0
Deferred revenue and prepaid rents	0	0
Deferred tax liability	0
Total liabilities	0	0
Total stockholders’ equity	22.2	17.2
Total liabilities and equity	22.2	17.2
Parent Guarantor
Condensed Consolidating Balance Sheets
Total investment in real estate, net	0	0
Cash and cash equivalents	0	0
Investment in subsidiaries	2,216.9	1,718
Rent and other receivables, net	0	0
Intercompany receivable	23.2	20
GDS Equity investment	0	0
Goodwill	0	0
Intangible assets, net	0	0
Other assets	0	0
Total assets	2,240.1	1,738
Debt, net	0	0
Intercompany payable	0	0
Capital lease obligations and lease financing arrangements	0	0
Accounts payable and accrued expenses	0	0
Construction costs payable	0	0
Dividends payable	51	41.8
Deferred revenue and prepaid rents	0	0
Deferred tax liability	0
Total liabilities	51	41.8
Total stockholders’ equity	2,189.1	1,696.2
Total liabilities and equity	2,240.1	1,738
LP Co-issuer
Condensed Consolidating Balance Sheets
Total investment in real estate, net	0	0
Cash and cash equivalents	0	0
Investment in subsidiaries	3,122.5	2,190.2
Rent and other receivables, net	0	0
Intercompany receivable	1,761.5	1,656.4
GDS Equity investment	0	0
Goodwill	0	0
Intangible assets, net	0	0
Other assets	0.5	0.5
Total assets	4,884.5	3,847.1
Debt, net	2,624.7	2,089.4
Intercompany payable	23.2	20
Capital lease obligations and lease financing arrangements	0	0
Accounts payable and accrued expenses	19.7	19.7
Construction costs payable	0	0
Dividends payable	0	0
Deferred revenue and prepaid rents	0	0
Deferred tax liability	0
Total liabilities	2,667.6	2,129.1
Total stockholders’ equity	2,216.9	1,718
Total liabilities and equity	4,884.5	3,847.1
Finance Co-issuer
Condensed Consolidating Balance Sheets
Total investment in real estate, net	0	0
Cash and cash equivalents	0	0
Investment in subsidiaries	0	0
Rent and other receivables, net	0	0
Intercompany receivable	0	0
GDS Equity investment	0	0
Goodwill	0	0
Intangible assets, net	0	0
Other assets	0	0
Total assets	0	0
Debt, net	0	0
Intercompany payable	0	0
Capital lease obligations and lease financing arrangements	0	0
Accounts payable and accrued expenses	0	0
Construction costs payable	0	0
Dividends payable	0	0
Deferred revenue and prepaid rents	0	0
Deferred tax liability	0
Total liabilities	0	0
Total stockholders’ equity	0	0
Total liabilities and equity	0	0
Guarantor Subsidiaries
Condensed Consolidating Balance Sheets
Total investment in real estate, net	3,611.2	3,014.9
Cash and cash equivalents	27.2	151.2
Investment in subsidiaries	0	0
Rent and other receivables, net	93.3	84.6
Intercompany receivable	6.8	0
GDS Equity investment	0	0
Goodwill	455.1	455.1
Intangible assets, net	178.1	203
Other assets	219.8	177.7
Total assets	4,591.5	4,086.5
Debt, net	0	0
Intercompany payable	1,761.5	1,656.4
Capital lease obligations and lease financing arrangements	104	110
Accounts payable and accrued expenses	95.9	77.3
Construction costs payable	175.6	115.5
Dividends payable	0	0
Deferred revenue and prepaid rents	144.9	110.8
Deferred tax liability	0
Total liabilities	2,281.9	2,070
Total stockholders’ equity	2,309.6	2,016.5
Total liabilities and equity	4,591.5	4,086.5
Non- Guarantors
Condensed Consolidating Balance Sheets
Total investment in real estate, net	644.9	25.8
Cash and cash equivalents	37.2	0.7
Investment in subsidiaries	0	0
Rent and other receivables, net	12.9	2.6
Intercompany receivable	0	0
GDS Equity investment	198.1	175.6
Goodwill	0	0
Intangible assets, net	57.6	0
Other assets	19.7	2.7
Total assets	970.4	207.4
Debt, net	0	0
Intercompany payable	6.8	0
Capital lease obligations and lease financing arrangements	52.7	32
Accounts payable and accrued expenses	5.7	0.9
Construction costs payable	19.7	0
Dividends payable	0	0
Deferred revenue and prepaid rents	3.7	0.8
Deferred tax liability	68.9
Total liabilities	157.5	33.7
Total stockholders’ equity	812.9	173.7
Total liabilities and equity	$ 970.4	$ 207.4

Guarantors - Consolidating Stat

Guarantors - Consolidating Statements of Operations and Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Consolidating Statements of Operations
Revenue	$ 221.3	$ 206.6	$ 196.9	$ 196.6	$ 180.5	$ 175.3	$ 166.9	$ 149.3	$ 821.4	$ 672	$ 529.1
Total operating expenses									731.7	647.9	458.6
Operating income	14.8	20.2	27	27.7	23.9	(36.3)	16.7	19.8	89.7	24.1	70.5
Interest expense									(94.7)	(68.1)	(48.8)
Unrealized gain on marketable equity investment									9.9	0	0
Loss on early extinguishment of debt									(3.1)	(36.5)	0
Net income (loss) before income taxes									1.8	(80.5)	21.7
Income tax expense									(0.6)	(3)	(1.8)
Equity (loss) earnings related to investment in subsidiaries									0	0	0
Net income (loss)	$ (105.8)	$ (42.4)	$ 105.9	$ 43.5	$ 2.8	$ (55.1)	$ (0.8)	$ (30.4)	1.2	(83.5)	19.9
Other comprehensive loss									(10.9)	75.5	(0.9)
Comprehensive income (loss)									(9.7)	(8)	19
Eliminations/Consolidations
Condensed Consolidating Statements of Operations
Revenue									0	0	0
Total operating expenses									0	0	0
Operating income									0	0	0
Interest expense									19.2	10.7	3.1
Unrealized gain on marketable equity investment									0
Loss on early extinguishment of debt									0	0
Net income (loss) before income taxes									19.2	10.7	3.1
Income tax expense									0	0	0
Equity (loss) earnings related to investment in subsidiaries									(55.6)	(70.5)	(81.7)
Net income (loss)									(36.4)	(59.8)	(78.6)
Other comprehensive loss									0	0	0
Comprehensive income (loss)									(36.4)	(59.8)	(78.6)
Parent Guarantor
Condensed Consolidating Statements of Operations
Revenue									0	0	0
Total operating expenses									0	0	0
Operating income									0	0	0
Interest expense									0	0	0
Unrealized gain on marketable equity investment									0
Loss on early extinguishment of debt									0	0
Net income (loss) before income taxes									0	0	0
Income tax expense									0	0	0
Equity (loss) earnings related to investment in subsidiaries									(28.9)	(18.7)	15.9
Net income (loss)									(28.9)	(18.7)	15.9
Other comprehensive loss									0	0	0
Comprehensive income (loss)									(28.9)	(18.7)	15.9
LP Co-issuer
Condensed Consolidating Statements of Operations
Revenue									0	0	0
Total operating expenses									0	0	0
Operating income									0	0	0
Interest expense									(110.6)	(76.2)	(49.1)
Unrealized gain on marketable equity investment									0
Loss on early extinguishment of debt									(3.1)	(36.5)
Net income (loss) before income taxes									(113.7)	(112.7)	(49.1)
Income tax expense									0	0	0
Equity (loss) earnings related to investment in subsidiaries									84.8	94	65
Net income (loss)									(28.9)	(18.7)	15.9
Other comprehensive loss									0	0	0
Comprehensive income (loss)									(28.9)	(18.7)	15.9
Finance Co-issuer
Condensed Consolidating Statements of Operations
Revenue									0	0	0
Total operating expenses									0	0	0
Operating income									0	0	0
Interest expense									0	0	0
Unrealized gain on marketable equity investment									0
Loss on early extinguishment of debt									0	0
Net income (loss) before income taxes									0	0	0
Income tax expense									0	0	0
Equity (loss) earnings related to investment in subsidiaries									0	0	0
Net income (loss)									0	0	0
Other comprehensive loss									0	0	0
Comprehensive income (loss)									0	0	0
Guarantor Subsidiaries
Condensed Consolidating Statements of Operations
Revenue									799.7	666.4	523.7
Total operating expenses									700.2	640.4	457.5
Operating income									99.5	26	66.2
Interest expense									0	0	0
Unrealized gain on marketable equity investment									0
Loss on early extinguishment of debt									0	0
Net income (loss) before income taxes									99.5	26	66.2
Income tax expense									(3)	(3)	(1.8)
Equity (loss) earnings related to investment in subsidiaries									0	(4.6)	0.6
Net income (loss)									96.5	18.4	65
Other comprehensive loss									0	0	0
Comprehensive income (loss)									96.5	18.4	65
Non- Guarantors
Condensed Consolidating Statements of Operations
Revenue									21.7	5.6	5.4
Total operating expenses									31.5	7.5	1.1
Operating income									(9.8)	(1.9)	4.3
Interest expense									(3.3)	(2.6)	(2.8)
Unrealized gain on marketable equity investment									9.9
Loss on early extinguishment of debt									0	0
Net income (loss) before income taxes									(3.2)	(4.5)	1.5
Income tax expense									2.4	0	0
Equity (loss) earnings related to investment in subsidiaries									0	0	0
Net income (loss)									(0.8)	(4.5)	1.5
Other comprehensive loss									(10.9)	75.5	(0.9)
Comprehensive income (loss)									(11.7)	71	0.6
General Partner
Condensed Consolidating Statements of Operations
Revenue									0	0	0
Total operating expenses									0	0	0
Operating income									0	0	0
Interest expense									0	0	0
Unrealized gain on marketable equity investment									0
Loss on early extinguishment of debt									0	0
Net income (loss) before income taxes									0	0	0
Income tax expense									0	0	0
Equity (loss) earnings related to investment in subsidiaries									(0.3)	(0.2)	0.2
Net income (loss)									(0.3)	(0.2)	0.2
Other comprehensive loss									0	0	0
Comprehensive income (loss)									$ (0.3)	$ (0.2)	$ 0.2

Guarantors - Consolidating St_2

Guarantors - Consolidating Statements of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities	$ 309.3	$ 289.5	$ 180.6
Cash flows from investing activities:
Asset acquisitions, primarily real estate, net of cash acquired	(462.8)	(492.3)	(131.1)
Investment in real estate	(865.7)	(914.5)	(600)
Equity investment	(12.6)	(100)	0
Investment in subsidiaries	0	0	0
Return of investment	0	0	0
Intercompany borrowings	0	0	0
Net cash used in investing activities	(1,341.1)	(1,506.8)	(731.1)
Cash flows from financing activities:
Issuance of common stock, net	699.6	705.7	447.1
Stock issuance costs	0
Dividends paid	(181.1)	(145.7)	(114.3)
Intercompany borrowings	0	0	0
Proceeds from debt, net	1,988.3	2,558.4	701.3
Payments on debt	(1,547.4)	(1,749.8)	(461.5)
Payments on capital lease obligations and lease financing arrangements	(9.5)	(9.8)	(9.1)
Interest paid by lenders on issuance of the senior notes	0	2.7	0
Tax payment upon exercise of equity awards	(5.2)	(6.9)	(14.2)
Contributions/distributions from parent	0	0	0
Net cash provided by financing activities	944.7	1,354.6	549.3
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(0.4)	0	0
Net increase (decrease) in cash, cash equivalents and restricted cash	(87.5)	137.3	(1.2)
Cash, cash equivalents and restricted cash at beginning of period	151.9	14.6	15.8
Cash, cash equivalents and restricted cash at end of period	64.4	151.9	14.6
General Partner
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities	0	0	0
Cash flows from investing activities:
Asset acquisitions, primarily real estate, net of cash acquired	0	0	0
Investment in real estate	0	0	0
Equity investment	0	0
Investment in subsidiaries	(7)	(7.1)	(4.5)
Return of investment	0	0	0
Intercompany borrowings	0	0	0
Net cash used in investing activities	(7)	(7.1)	(4.5)
Cash flows from financing activities:
Issuance of common stock, net	0	0	0
Stock issuance costs	0
Dividends paid	0	0	0
Intercompany borrowings	0	0	0
Proceeds from debt, net	0	0	0
Payments on debt	0	0	0
Payments on capital lease obligations and lease financing arrangements	0	0	0
Interest paid by lenders on issuance of the senior notes	0	0
Tax payment upon exercise of equity awards	0	0	0
Contributions/distributions from parent	7	7.1	4.5
Net cash provided by financing activities	7	7.1	4.5
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0
Net increase (decrease) in cash, cash equivalents and restricted cash	0	0	0
Cash, cash equivalents and restricted cash at beginning of period	0	0	0
Cash, cash equivalents and restricted cash at end of period	0	0	0
Parent Guarantor
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities	0	0	0
Cash flows from investing activities:
Asset acquisitions, primarily real estate, net of cash acquired	0	0	0
Investment in real estate	0	0	0
Equity investment	0	0
Investment in subsidiaries	(700)	(705.3)	(448.2)
Return of investment	181.1	145.7	112.3
Intercompany borrowings	5.6	6.5	15.3
Net cash used in investing activities	(513.3)	(553.1)	(320.6)
Cash flows from financing activities:
Issuance of common stock, net	699.6	705.7	447.1
Stock issuance costs	0
Dividends paid	(181.1)	(145.7)	(112.3)
Intercompany borrowings	0	0	0
Proceeds from debt, net	0	0	0
Payments on debt	0	0	0
Payments on capital lease obligations and lease financing arrangements	0	0	0
Interest paid by lenders on issuance of the senior notes	0	0
Tax payment upon exercise of equity awards	(5.2)	(6.9)	(14.2)
Contributions/distributions from parent	0	0	0
Net cash provided by financing activities	513.3	553.1	320.6
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0
Net increase (decrease) in cash, cash equivalents and restricted cash	0	0	0
Cash, cash equivalents and restricted cash at beginning of period	0	0	0
Cash, cash equivalents and restricted cash at end of period	0	0	0
LP Co-issuer
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities	(103.6)	(60.3)	(45.4)
Cash flows from investing activities:
Asset acquisitions, primarily real estate, net of cash acquired	0	0	0
Investment in real estate	0	0	0
Equity investment	0	0
Investment in subsidiaries	(829.5)	(705.3)	(448.2)
Return of investment	0	0	0
Intercompany borrowings	(105.1)	(598.8)	(66.3)
Net cash used in investing activities	(934.6)	(1,304.1)	(514.5)
Cash flows from financing activities:
Issuance of common stock, net	0	0	0
Stock issuance costs	0
Dividends paid	(181.1)	(145.7)	(114.3)
Intercompany borrowings	(5.6)	(6.5)	(15.3)
Proceeds from debt, net	1,958.4	2,558.4	701.3
Payments on debt	(1,432.7)	(1,749.8)	(460)
Payments on capital lease obligations and lease financing arrangements	0	0	0
Interest paid by lenders on issuance of the senior notes	0	2.7
Tax payment upon exercise of equity awards	0	0	0
Contributions/distributions from parent	700	705.3	448.2
Net cash provided by financing activities	1,039	1,364.4	559.9
Effect of exchange rate changes on cash, cash equivalents and restricted cash	(0.8)
Net increase (decrease) in cash, cash equivalents and restricted cash	0	0	0
Cash, cash equivalents and restricted cash at beginning of period	0	0	0
Cash, cash equivalents and restricted cash at end of period	0	0	0
Finance Co-issuer
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities	0	0	0
Cash flows from investing activities:
Asset acquisitions, primarily real estate, net of cash acquired	0	0	0
Investment in real estate	0	0	0
Equity investment	0	0
Investment in subsidiaries	0	0	0
Return of investment	0	0	0
Intercompany borrowings	0	0	0
Net cash used in investing activities	0	0	0
Cash flows from financing activities:
Issuance of common stock, net	0	0	0
Stock issuance costs	0
Dividends paid	0	0	0
Intercompany borrowings	0	0	0
Proceeds from debt, net	0	0	0
Payments on debt	0	0	0
Payments on capital lease obligations and lease financing arrangements	0	0	0
Interest paid by lenders on issuance of the senior notes	0	0
Tax payment upon exercise of equity awards	0	0	0
Contributions/distributions from parent	0	0	0
Net cash provided by financing activities	0	0	0
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0
Net increase (decrease) in cash, cash equivalents and restricted cash	0	0	0
Cash, cash equivalents and restricted cash at beginning of period	0	0	0
Cash, cash equivalents and restricted cash at end of period	0	0	0
Guarantor Subsidiaries
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities	421.6	339.7	221.8
Cash flows from investing activities:
Asset acquisitions, primarily real estate, net of cash acquired	0	(492.3)	(131.1)
Investment in real estate	(814.6)	(903.8)	(598.9)
Equity investment	0	0
Investment in subsidiaries	0	(0.7)	0
Return of investment	0	0	0
Intercompany borrowings	(6.8)	0	0
Net cash used in investing activities	(821.4)	(1,396.8)	(730)
Cash flows from financing activities:
Issuance of common stock, net	0	0	0
Stock issuance costs	0
Dividends paid	0	0	0
Intercompany borrowings	105.1	598.2	71
Proceeds from debt, net	0	0	0
Payments on debt	0	0	(1.5)
Payments on capital lease obligations and lease financing arrangements	(7.9)	(8.6)	(8)
Interest paid by lenders on issuance of the senior notes	0	0
Tax payment upon exercise of equity awards	0	0	0
Contributions/distributions from parent	178.6	605.3	448.2
Net cash provided by financing activities	275.8	1,194.9	509.7
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0
Net increase (decrease) in cash, cash equivalents and restricted cash	(124)	137.8	1.5
Cash, cash equivalents and restricted cash at beginning of period	151.2	13.4	11.9
Cash, cash equivalents and restricted cash at end of period	27.2	151.2	13.4
Non- Guarantors
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities	(27.9)	(0.6)	0
Cash flows from investing activities:
Asset acquisitions, primarily real estate, net of cash acquired	(462.8)	0	0
Investment in real estate	(31.9)	0	(1.1)
Equity investment	(12.6)	(100)
Investment in subsidiaries	0	0	0
Return of investment	0	0	0
Intercompany borrowings	0	0.5	(0.5)
Net cash used in investing activities	(507.3)	(99.5)	(1.6)
Cash flows from financing activities:
Issuance of common stock, net	0	0	0
Stock issuance costs	0
Dividends paid	0	0	0
Intercompany borrowings	6.8	0	0
Proceeds from debt, net	29.9	0	0
Payments on debt	(114.7)	0	0
Payments on capital lease obligations and lease financing arrangements	(1.6)	(1.2)	(1.1)
Interest paid by lenders on issuance of the senior notes	0	0
Tax payment upon exercise of equity awards	0	0	0
Contributions/distributions from parent	650.9	100.8	0
Net cash provided by financing activities	571.3	99.6	(1.1)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0.4
Net increase (decrease) in cash, cash equivalents and restricted cash	36.5	(0.5)	(2.7)
Cash, cash equivalents and restricted cash at beginning of period	0.7	1.2	3.9
Cash, cash equivalents and restricted cash at end of period	37.2	0.7	1.2
Eliminations/Consolidations
Condensed Consolidating Statements of Cash Flows
Net cash (used in) provided by operating activities	19.2	10.7	4.2
Cash flows from investing activities:
Asset acquisitions, primarily real estate, net of cash acquired	0	0	0
Investment in real estate	(19.2)	(10.7)	0
Equity investment	0	0
Investment in subsidiaries	1,536.5	1,418.4	900.9
Return of investment	(181.1)	(145.7)	(112.3)
Intercompany borrowings	106.3	591.8	51.5
Net cash used in investing activities	1,442.5	1,853.8	840.1
Cash flows from financing activities:
Issuance of common stock, net	0	0	0
Stock issuance costs	0
Dividends paid	181.1	145.7	112.3
Intercompany borrowings	(106.3)	(591.7)	(55.7)
Proceeds from debt, net	0	0	0
Payments on debt	0	0	0
Payments on capital lease obligations and lease financing arrangements	0	0	0
Interest paid by lenders on issuance of the senior notes	0	0
Tax payment upon exercise of equity awards	0	0	0
Contributions/distributions from parent	(1,536.5)	(1,418.5)	(900.9)
Net cash provided by financing activities	(1,461.7)	(1,864.5)	(844.3)
Effect of exchange rate changes on cash, cash equivalents and restricted cash	0
Net increase (decrease) in cash, cash equivalents and restricted cash	0	0	0
Cash, cash equivalents and restricted cash at beginning of period	0	0	0
Cash, cash equivalents and restricted cash at end of period	$ 0	$ 0	$ 0

Quarterly Financial Informati_3

Quarterly Financial Information (Unaudited) - Schedule of Quarterly Information (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 221.3	$ 206.6	$ 196.9	$ 196.6	$ 180.5	$ 175.3	$ 166.9	$ 149.3	$ 821.4	$ 672	$ 529.1
Operating income	14.8	20.2	27	27.7	23.9	(36.3)	16.7	19.8	89.7	24.1	70.5
Net income (loss)	(105.8)	(42.4)	105.9	43.5	2.8	(55.1)	(0.8)	(30.4)	1.2	(83.5)	$ 19.9
Net (loss) income available to stockholders, Basic	$ (105.8)	$ (42.4)	$ 105.9	$ 43.5	$ 2.8	$ (55.1)	$ (0.8)	$ (30.4)	$ 1.2	$ (83.5)
Basic and diluted income (loss) per share (in dollars per share)					$ 0.03	$ (0.61)	$ (0.01)	$ (0.36)		$ (0.95)
Income (loss) per share - basic (in dollars per share)	$ (1.09)	$ (0.43)	$ 1.07	$ 0.45					$ 0	(0.95)	$ 0.24
Income (loss) per share - diluted (in dollars per share)	$ (1.08)	$ (0.43)	$ 1.06	$ 0.45					$ 0	$ (0.95)	$ 0.24

Schedule II. Valuation and Qu_2

Schedule II. Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	$ 2.1	$ 2.1	$ 1
Charge to Expenses	2.3	0.2	1.6
(Deductions)/Additions	(2.7)	(0.2)	(0.5)
End of Period	1.7	2.1	2.1
Deferred Tax Valuation Allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	7.2	6.5	6.3
Charge to Expenses	(0.3)	0.7	0.2
(Deductions)/Additions	0	0	0
End of Period	$ 6.9	$ 7.2	$ 6.5

Schedule III. Real Estate Pro_2

Schedule III. Real Estate Properties and Accumulated Depreciation - Schedule of Real Estate Properties (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Initial Costs
Land	$ 117.7
Building and Improvements	609.6
Equipment	543
Cost Capitalized Subsequent to Acquisition
Land	0.8
Building and Improvements	1,067.9
Equipment	2,087.2
Gross Carrying Amount
Land	118.5	$ 104.6
Building and Improvements	1,677.5	1,371.4
Equipment	2,630.2	1,813.9
Accumulated Depreciation	1,054.5	782.4	$ 578.5	$ 435.6
Aggregate cost of the total properties for federal income tax purposes	6,186.5
Construction in progress, including land under development	744.9	487.1
Land held for future development	176.4	63.8
Dallas - Carrollton
Initial Costs
Land	16.1
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	62.2
Equipment	272.5
Gross Carrying Amount
Land	16.1	16.1
Building and Improvements	62.2	61.8
Equipment	272.5	210.7
Accumulated Depreciation	104
Houston - Houston West I
Initial Costs
Land	1.4
Building and Improvements	21.4
Equipment	0.1
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	63.8
Equipment	51
Gross Carrying Amount
Land	1.4	1.4
Building and Improvements	85.2	85.2
Equipment	51.1	49.8
Accumulated Depreciation	83.2
Northern Virginia - Sterling II
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	28.8
Equipment	112.4
Gross Carrying Amount
Land	0	0
Building and Improvements	28.8	28.8
Equipment	112.4	112.3
Accumulated Depreciation	26.8
San Antonio III
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	40.2
Equipment	99
Gross Carrying Amount
Land	0	0
Building and Improvements	40.2	40.3
Equipment	99	96.8
Accumulated Depreciation	19.5
Cincinnati - 7th Street
Initial Costs
Land	0.9
Building and Improvements	42.2
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	71.9
Equipment	37.4
Gross Carrying Amount
Land	0.9	0.9
Building and Improvements	114.1	110.6
Equipment	37.4	33.1
Accumulated Depreciation	93.3
Northern Virginia - Sterling V
Initial Costs
Land	14.5
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	80.8
Equipment	295.8
Gross Carrying Amount
Land	14.5	14.5
Building and Improvements	80.8	35.7
Equipment	295.8	108.8
Accumulated Depreciation	26
Northern Virginia - Sterling VI
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0
Equipment	77.5
Gross Carrying Amount
Land	0	0
Building and Improvements	0	0
Equipment	77.5	0
Accumulated Depreciation	0.9
Somerset I
Initial Costs
Land	12.1
Building and Improvements	124.6
Equipment	83.3
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	1.2
Equipment	7.7
Gross Carrying Amount
Land	12.1	9.3
Building and Improvements	125.8	124.8
Equipment	91	83.7
Accumulated Depreciation	27
Dallas - Lewisville
Initial Costs
Land	0
Building and Improvements	46.2
Equipment	2.2
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	30.6
Equipment	37.4
Gross Carrying Amount
Land	0	0
Building and Improvements	76.8	76.7
Equipment	39.6	37.4
Accumulated Depreciation	70.7
Totowa - Madison
Initial Costs
Land	0
Building and Improvements	28.3
Equipment	45.6
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0.2
Equipment	12.1
Gross Carrying Amount
Land	0	0
Building and Improvements	28.5	28.5
Equipment	57.7	55.1
Accumulated Depreciation	29.4
Chicago - Aurora I
Initial Costs
Land	2.4
Building and Improvements	26
Equipment	97.3
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	6.4
Equipment	35.6
Gross Carrying Amount
Land	2.4	2.4
Building and Improvements	32.4	32.4
Equipment	132.9	125
Accumulated Depreciation	40.4
Cincinnati - North Cincinnati
Initial Costs
Land	0.9
Building and Improvements	12.3
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	65.6
Equipment	12.4
Gross Carrying Amount
Land	0.9	0.9
Building and Improvements	77.9	77.4
Equipment	12.4	9.9
Accumulated Depreciation	42.2
Phoenix - Chandler II
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	16.2
Equipment	39.4
Gross Carrying Amount
Land	0	0
Building and Improvements	16.2	16.2
Equipment	39.4	38.9
Accumulated Depreciation	20
Wappingers Falls I
Initial Costs
Land	0
Building and Improvements	9.9
Equipment	13.3
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	1.4
Equipment	8.7
Gross Carrying Amount
Land	0	0
Building and Improvements	11.3	11.3
Equipment	22	18
Accumulated Depreciation	13.8
San Antonio I
Initial Costs
Land	4.6
Building and Improvements	3
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	28.7
Equipment	35.3
Gross Carrying Amount
Land	4.6	4.6
Building and Improvements	31.7	31.7
Equipment	35.3	34.8
Accumulated Depreciation	30.9
Houston - Houston West II
Initial Costs
Land	2
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0.7
Building and Improvements	22.9
Equipment	50.9
Gross Carrying Amount
Land	2.7	2.7
Building and Improvements	22.9	22.8
Equipment	50.9	50.1
Accumulated Depreciation	33.7
Phoenix - Chandler I
Initial Costs
Land	10.5
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	58.3
Equipment	68.7
Gross Carrying Amount
Land	10.5	10.5
Building and Improvements	58.3	58.2
Equipment	68.7	65.9
Accumulated Depreciation	45.1
Phoenix - Chandler III
Initial Costs
Land	0
Building and Improvements	0.9
Equipment	2.5
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	10.5
Equipment	48.3
Gross Carrying Amount
Land	0	0
Building and Improvements	11.4	11.4
Equipment	50.8	50
Accumulated Depreciation	11.6
Northern Virginia - Sterling I
Initial Costs
Land	6.9
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	20.2
Equipment	60.4
Gross Carrying Amount
Land	6.9	7
Building and Improvements	20.2	20
Equipment	60.4	59.4
Accumulated Depreciation	24.6
Raleigh-Durham I
Initial Costs
Land	2.1
Building and Improvements	73.5
Equipment	71.3
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	6.3
Equipment	4.1
Gross Carrying Amount
Land	2.1	2.1
Building and Improvements	79.8	78
Equipment	75.4	76
Accumulated Depreciation	21.8
Houston - Galleria
Initial Costs
Land	0
Building and Improvements	56
Equipment	2
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	15
Equipment	18.2
Gross Carrying Amount
Land	0	0
Building and Improvements	71	68.6
Equipment	20.2	17.6
Accumulated Depreciation	56
Phoenix - Chandler VI
Initial Costs
Land	2.3
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0.1
Building and Improvements	23.3
Equipment	100.3
Gross Carrying Amount
Land	2.4	2.4
Building and Improvements	23.3	15.7
Equipment	100.3	49.2
Accumulated Depreciation	10.4
Northern Virginia - Sterling III
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	22.2
Equipment	61.3
Gross Carrying Amount
Land	0	0
Building and Improvements	22.2	22.2
Equipment	61.3	61.3
Accumulated Depreciation	12.5
Frankfurt I
Initial Costs
Land	11.2
Building and Improvements	31
Equipment	106.2
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	94.5
Equipment	72.6
Gross Carrying Amount
Land	11.2	0
Building and Improvements	125.5	0
Equipment	178.8	0
Accumulated Depreciation	5.3
Austin II
Initial Costs
Land	2
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	23.4
Equipment	8.7
Gross Carrying Amount
Land	2	2
Building and Improvements	23.4	23.4
Equipment	8.7	7.2
Accumulated Depreciation	16.9
San Antonio II
Initial Costs
Land	6.7
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0.3
Building and Improvements	30.3
Equipment	60.8
Gross Carrying Amount
Land	7	7
Building and Improvements	30.3	29
Equipment	60.8	60.4
Accumulated Depreciation	17.5
Florence
Initial Costs
Land	2.2
Building and Improvements	7.7
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	34.3
Equipment	8.4
Gross Carrying Amount
Land	2.2	2.2
Building and Improvements	42	42
Equipment	8.4	5.3
Accumulated Depreciation	32.7
Austin III
Initial Costs
Land	3.3
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	11.7
Equipment	47
Gross Carrying Amount
Land	3.3	3.3
Building and Improvements	11.7	10.6
Equipment	47	33.9
Accumulated Depreciation	11.3
Phoenix - Chandler IV
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	18.4
Equipment	43.3
Gross Carrying Amount
Land	0	0
Building and Improvements	18.4	18.3
Equipment	43.3	40.9
Accumulated Depreciation	6.8
San Antonio IV
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	42.1
Equipment	48.2
Gross Carrying Amount
Land	0	0
Building and Improvements	42.1	0
Equipment	48.2	17.9
Accumulated Depreciation	5.4
Cincinnati - Hamilton
Initial Costs
Land	0
Building and Improvements	9.5
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	34.2
Equipment	7.9
Gross Carrying Amount
Land	0	0
Building and Improvements	43.7	50.2
Equipment	7.9	6
Accumulated Depreciation	29.9
Northern Virginia - Sterling IV
Initial Costs
Land	4.6
Building and Improvements	9.6
Equipment	0.1
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	10.4
Equipment	75.9
Gross Carrying Amount
Land	4.6	4.6
Building and Improvements	20	20
Equipment	76	73.7
Accumulated Depreciation	12.9
Phoenix - Chandler V
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	10.7
Equipment	53.4
Gross Carrying Amount
Land	0	0
Building and Improvements	10.7	5.9
Equipment	53.4	20.5
Accumulated Depreciation	4
London II
Initial Costs
Land	0
Building and Improvements	19.9
Equipment	58.7
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	5.3
Equipment	16.1
Gross Carrying Amount
Land	0	0
Building and Improvements	25.2	0
Equipment	74.8	0
Accumulated Depreciation	4.4
London I
Initial Costs
Land	0
Building and Improvements	25.3
Equipment	20.5
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	8.8
Equipment	5.8
Gross Carrying Amount
Land	0	0
Building and Improvements	34.1	0
Equipment	26.3	0
Accumulated Depreciation	1.3
Stamford - Riverbend
Initial Costs
Land	0
Building and Improvements	4.3
Equipment	13.2
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	(1.4)
Equipment	(5.4)
Gross Carrying Amount
Land	0	0
Building and Improvements	2.9	2.9
Equipment	7.8	6.9
Accumulated Depreciation	5
Cincinnati - Mason
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	20.3
Equipment	1.7
Gross Carrying Amount
Land	0	0
Building and Improvements	20.3	20.3
Equipment	1.7	1.6
Accumulated Depreciation	14.8
Cincinnati - Blue Ash
Initial Costs
Land	0
Building and Improvements	2.6
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	(1.9)
Equipment	0.2
Gross Carrying Amount
Land	0	0
Building and Improvements	0.7	0.7
Equipment	0.2	0.2
Accumulated Depreciation	0.5
Houston - Houston West III
Initial Costs
Land	7.1
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0.1
Building and Improvements	18
Equipment	31.4
Gross Carrying Amount
Land	7.2	7.2
Building and Improvements	18	17.9
Equipment	31.4	30.7
Accumulated Depreciation	9.7
Norwalk I
Initial Costs
Land	0
Building and Improvements	18.3
Equipment	25.3
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	(4.7)
Equipment	(15.2)
Gross Carrying Amount
Land	0	0
Building and Improvements	13.6	13.5
Equipment	10.1	9.4
Accumulated Depreciation	4.5
Chicago - Lombard
Initial Costs
Land	0.7
Building and Improvements	3.2
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	1.5
Equipment	8.1
Gross Carrying Amount
Land	0.7	0.7
Building and Improvements	4.7	4.7
Equipment	8.1	7.7
Accumulated Depreciation	7.7
Stamford - Omega
Initial Costs
Land	0
Building and Improvements	3.2
Equipment	0.6
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	(0.6)
Equipment	0.1
Gross Carrying Amount
Land	0	0
Building and Improvements	2.6	2.6
Equipment	0.7	0.7
Accumulated Depreciation	0.7
Cincinnati - Goldcoast
Initial Costs
Land	0.6
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	(0.4)
Building and Improvements	4
Equipment	0.1
Gross Carrying Amount
Accumulated Depreciation	3.1
Totowa - Commerce
Initial Costs
Land	0
Building and Improvements	4.1
Equipment	0.8
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0
Equipment	0.9
Gross Carrying Amount
Land	0	0
Building and Improvements	4.1	4.1
Equipment	1.7	1.6
Accumulated Depreciation	1.3
South Bend - Crescent
Initial Costs
Land	0
Building and Improvements	1.1
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0.6
Equipment	0.2
Gross Carrying Amount
Land	0	0
Building and Improvements	1.7	1.7
Equipment	0.2	0.1
Accumulated Depreciation	1.8
South Bend - Monroe
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	2.5
Equipment	0.4
Gross Carrying Amount
Land	0	0
Building and Improvements	2.5	2.5
Equipment	0.4	0.3
Accumulated Depreciation	1.8
Singapore - Inter Business Park
Initial Costs
Land	0
Building and Improvements	9
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	(9)
Equipment	0
Gross Carrying Amount
Land	0
Building and Improvements	0
Equipment	0
Accumulated Depreciation	0
Chicago - Aurora II
Initial Costs
Land	2.6
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	22.6
Equipment	68.6
Gross Carrying Amount
Land	2.6	2.6
Building and Improvements	22.6	8.3
Equipment	68.6	42.9
Accumulated Depreciation	7.1
Chicago - Aurora Tower
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	4.9
Equipment	0.4
Gross Carrying Amount
Land	0	0
Building and Improvements	4.9	0
Equipment	0.4	0
Accumulated Depreciation	0.1
London - Great Bridgewater
Initial Costs
Land	0
Building and Improvements	16.5
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	10.3
Equipment	1.2
Gross Carrying Amount
Land	0	0
Building and Improvements	26.8	28.4
Equipment	1.2	$ 1.1
Accumulated Depreciation	$ 4.2

Schedule III. Real Estate Pro_3

Schedule III. Real Estate Properties and Accumulated Depreciation - Historical Cost and Accumulated Depreciation and Amortization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property
Balance—beginning of period	$ 3,840.8	$ 2,601.6	$ 1,827.6
Disposals	(20.8)	(3.4)	(12)
Impairments	0	(71.8)	(4.9)
Additions (acquisitions and improvements)	1,527.5	1,314.4	790.9
Balance, end of period(1)	5,347.5	3,840.8	2,601.6
Accumulated Depreciation
Balance—beginning of period	782.4	578.5	435.6
Disposals	(14)	(1.9)	(7.9)
Impairments	0	(14.1)	0
Additions (depreciation and amortization expense)	286.1	219.9	150.8
Balance, end of period	$ 1,054.5	$ 782.4	$ 578.5

Uncategorized Items - cone-2018

Label	Element	Value
Accounting Standards Update 2016-01 [Member] | AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (75,600,000)
Accounting Standards Update 2016-01 [Member] | Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	0
Accounting Standards Update 2014-09 [Member] | Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 300,000