CyrusOne (CONE) 10-K 26 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2015	Jan. 29, 2016	Jun. 30, 2015
Document and Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
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 Public Float			$ 1.9
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		72,270,518

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Investment in real estate:
Land	$ 93	$ 89.7
Buildings and improvements	905.3	812.6
Equipment	598.2	349.1
Construction in progress	231.1	127
Subtotal	1,827.6	1,378.4
Accumulated depreciation	(435.6)	(327)
Net investment in real estate	1,392	1,051.4
Cash and cash equivalents	14.3	36.5
Rent and other receivables (net of allowance for doubtful accounts of $1.0 and $1.0 as of December 31, 2015 and December 31, 2014, respectively)	76.1	60.9
Restricted cash	1.5	0
Goodwill	453.4	276.2
Intangible assets (net of accumulated amortization of $90.6 and $72.1 as of December 31, 2015 and December 31, 2014, respectively)	170.3	68.9
Due from affiliates	0	0.8
Other assets	88	76.3
Total assets	2,195.6	1,571
Liabilities and equity
Accounts payable and accrued expenses	136.6	69.9
Deferred revenue	78.7	65.7
Due to affiliates	0	7.3
Capital lease obligations	12.2	13.4
Long-term debt	996.5	644.3
Lease financing arrangements	150	53.4
Total liabilities	$ 1,374	$ 854
Commitment and contingencies
Equity
Preferred stock, $.01 par value, 100,000,000 authorized; no shares issued or outstanding	$ 0	$ 0
Common stock, $.01 par value, 500,000,000 shares authorized and 72,556,334 and 38,651,517 shares issued and outstanding at December 31, 2015 and December 31, 2014, respectively	0.7	0.4
Additional paid in capital	967.2	516.5
Accumulated deficit	(145.9)	(55.9)
Accumulated other comprehensive loss	(0.4)	(0.2)
Total shareholders’ equity	821.6	460.8
Noncontrolling interest	0	256.2
Total equity	821.6	717
Total liabilities and equity	$ 2,195.6	$ 1,571

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 1	$ 1
Accumulated amortization of intangible assets	$ 90.6	$ 72.1
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)	72,556,334	38,651,517
Common stock outstanding (in shares)	72,556,334	38,651,517

Consolidated and Combined State

Consolidated and Combined Statements of Operations - USD ($) shares in Millions, $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 23, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Revenue	$ 15.1	$ 248.4	$ 399.3	$ 330.9
Costs and expenses:
Property operating expenses	4.8	88.4	148.7	124.5
Sales and marketing	0.7	9.9	12.1	12.8
General and administrative	1.5	26.5	46.6	34.6
Depreciation and amortization	5.3	89.9	141.5	118
Restructuring charges		0.7
Transaction and acquisition integration costs	0.1	1.3	14.1	1
Transaction-related compensation	20
Asset impairments and loss on disposal		2.8	13.5	0
Total costs and expenses	32.4	219.5	376.5	290.9
Operating income (loss)	(17.3)	28.9	22.8	40
Interest expense	2.5	41.2	41.2	39.5
Other income		(0.1)
Loss on extinguishment of debt		1.3	0	13.6
Net loss before income taxes	(19.8)	(13.5)	(18.4)	(13.1)
Income tax expense	(0.4)	(1.9)	(1.8)	(1.4)
Loss on sale of real estate improvements		(0.2)
Net loss	(20.2)	(15.6)	(20.2)	(14.5)
Noncontrolling interest in net loss		(10.3)	(4.8)	(6.7)
Net loss attributed to common shareholders		(5.3)	$ (15.4)	$ (7.8)
Basic weighted average common shares outstanding (in shares)			54.3	29.2
Diluted weighted average common shares outstanding (in shares)			54.3	29.2
Loss per share - basic and diluted (in dollars per share)			$ (0.30)	$ (0.30)
Successor
Revenue		248.4	$ 399.3	$ 330.9
Costs and expenses:
Property operating expenses		88.4	148.7	124.5
Sales and marketing		9.9	12.1	12.8
General and administrative		26.5	46.6	34.6
Depreciation and amortization		89.9	141.5	118
Restructuring charges		0.7	0	0
Transaction and acquisition integration costs		1.3	14.1	1
Transaction-related compensation		0	0	0
Asset impairments and loss on disposal		2.8	13.5	0
Total costs and expenses		219.5	376.5	290.9
Operating income (loss)		28.9	22.8	40
Interest expense		41.2	41.2	39.5
Other income		(0.1)	0	0
Loss on extinguishment of debt		1.3	0	13.6
Net loss before income taxes		(13.5)	(18.4)	(13.1)
Income tax expense		(1.9)	(1.8)	(1.4)
Loss on sale of real estate improvements		(0.2)	0	0
Net loss		(15.6)	(20.2)	(14.5)
Noncontrolling interest in net loss		(10.3)	(4.8)	(6.7)
Net loss attributed to common shareholders		$ (5.3)	$ (15.4)	$ (7.8)
Basic weighted average common shares outstanding (in shares)		20.9	54.3	29.2
Diluted weighted average common shares outstanding (in shares)		20.9	54.3	29.2
Loss per share - basic and diluted (in dollars per share)		$ (0.28)	$ (0.30)	$ (0.30)
Predecessor
Revenue	15.1
Costs and expenses:
Property operating expenses	4.8
Sales and marketing	0.7
General and administrative	1.5
Depreciation and amortization	5.3
Restructuring charges	0
Transaction and acquisition integration costs	0.1
Transaction-related compensation	20
Asset impairments and loss on disposal	0
Total costs and expenses	32.4
Operating income (loss)	(17.3)
Interest expense	2.5
Other income	0
Loss on extinguishment of debt	0
Net loss before income taxes	(19.8)
Income tax expense	(0.4)
Loss on sale of real estate improvements	0
Net loss	$ (20.2)

Consolidated and Combined Stat5

Consolidated and Combined Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 23, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Net loss	$ (20.2)	$ (15.6)	$ (20.2)	$ (14.5)
Other comprehensive loss:
Foreign currency translation adjustments			(0.2)	(0.3)
Comprehensive loss attributable to CyrusOne Inc.			(15.6)	(8)
Successor
Net loss		(15.6)	(20.2)	(14.5)
Other comprehensive loss:
Foreign currency translation adjustments		0	(0.2)	(0.3)
Comprehensive loss		(15.6)	(20.4)	(14.8)
Comprehensive loss attributable to noncontrolling interests		(10.3)	(4.8)	(6.8)
Comprehensive loss attributable to CyrusOne Inc.		$ (5.3)	$ (15.6)	$ (8)
Predecessor
Net loss	(20.2)
Other comprehensive loss:
Foreign currency translation adjustments	0
Comprehensive loss	(20.2)
Comprehensive loss attributable to noncontrolling interests	0
Comprehensive loss attributable to CyrusOne Inc.	$ (20.2)

Consolidated and Combined Stat6

Consolidated and Combined Statements of Equity - USD ($) shares in Millions, $ in Millions	Total	Common stock	Accum Deficit	Paid-In Capital	Partnership Capital	Accum Other Comprehensive Loss	Total Shareholder’s Equity/ Parent’s Net Investment	Non Controlling Interest
Beginning Balance (in shares) at Dec. 31, 2012		0
Beginning Balance at Dec. 31, 2012	$ 500.1	$ 0	$ 0	$ 7.1	$ 493	$ 0	$ 500.1	$ 0
Ending Balance at Dec. 31, 2013	777.6	$ 0.2	(18.9)	340.7	0	0	322	455.6
Ending Balance (in shares) at Dec. 31, 2013		22
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(14.5)		(14.5)				(14.5)
Common stock issued (in shares)		16
Common stock issued	356	$ 0.2		355.8			356
IPO costs	(1.3)			(1.3)			(1.3)
Noncontrolling interest in net loss	(6.7)		6.7				6.7	(6.7)
Stock based compensation (in shares)		0.7
Stock based compensation	10.3			10.3			10.3
Dividends declared	(54.9)		(29.2)				(29.2)	(25.7)
Foreign currency translation adjustments	(0.3)					(0.2)	(0.2)	(0.1)
Redemption of noncontrolling interest	(355.9)			(189)			(189)	(166.9)
Ending Balance at Dec. 31, 2014	717	$ 0.4	(55.9)	516.5	0	(0.2)	460.8	256.2
Ending Balance (in shares) at Dec. 31, 2014		38.7
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ (20.2)		(20.2)				(20.2)
Common stock issued (in shares)	0.2	33.6
Common stock issued	$ 799.5	$ 0.3		799.2			799.5
IPO costs	(0.8)			(0.8)			(0.8)
Noncontrolling interest in net loss	(4.8)		4.8				4.8	(4.8)
Stock based compensation (in shares)		0.3
Stock based compensation	14.4			14.4			14.4
Dividends declared	(90.9)		(74.6)				(74.6)	(16.3)
Foreign currency translation adjustments	(0.2)					(0.2)	(0.2)
Redemption of noncontrolling interest	(596.4)			(412.3)			(412.3)	(184.1)
Conversion of operating partnership units to common stock				51			51	(51)
Tax payment upon exercise of equity awards	(0.8)			(0.8)			(0.8)
Ending Balance at Dec. 31, 2015	$ 821.6	$ 0.7	$ (145.9)	$ 967.2	$ 0	$ (0.4)	$ 821.6	$ 0
Ending Balance (in shares) at Dec. 31, 2015		72.6

Consolidated and Combined Stat7

Consolidated and Combined Statements of Equity (Parenthetical) - $ / shares	11 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Dividends declared per share (in dollars per share)	$ 0.64	$ 1.26	$ 0.84

Consolidated and Combined Stat8

Consolidated and Combined Statements of Cash Flows - USD ($) $ in Millions	1 Months Ended	3 Months Ended				11 Months Ended	12 Months Ended
	Jan. 23, 2013	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Cash flows from operating activities:
Net loss	$ (20.2)	$ (1.2)	$ (7.2)	$ (11.8)	$ 0.7	$ (15.6)	$ (20.2)	$ (14.5)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	5.3					89.9	141.5	118
Provision for bad debt write off						0.4	0	0.8
Asset impairments and loss on disposal						2.8	13.5	0	$ 2.8
Loss on extinguishment of debt						1.3	0	13.6
Non-cash interest expense						4	3.4	3.4
Deferred income tax expense, including valuation allowance change						0.6
Stock-based compensation expense						6	14.4	10.3
Changes in operating assets and liabilities:
Rent receivables and other assets	(9.6)					(15.7)	(23.9)	(37)
Accounts payable and accrued expenses	20.5					(14.6)	7	6.9
Deferred revenues						(0.1)	5.4	9.8
Due to affiliates	1.5					18.4	(0.9)	(0.2)
Net cash provided by operating activities	2					77.4	140.2	111.1
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate						(48)	(17.3)
Capital expenditures – other development	(7.7)					(172.9)	(217.2)	(284.2)
Business acquisition, net of cash acquired							(398.4)
Changes in restricted cash	1.9					4.4	7.3	0
Other						(0.2)		0
Net cash used in investing activities	(5.8)					(216.7)	(625.6)	(284.2)
Cash flows from financing activities:
Issuance of common stock						360.5	799.5	356
Stock issuance costs							(0.8)
IPO costs						(26.6)		(1.3)
Acquisition of operating partnership units							(596.4)	(355.9)
Dividends paid						(31)	(80.8)	(50.9)
Borrowings from credit facility							260	315
Payments on credit facility							(10)	(30)
Payments on senior notes							0
Proceeds from issuance of debt							103.8
Payments on capital lease obligations	(0.6)					(5.3)	(5.9)	(150.2)
Payments on lease financing arrangements						(0.7)		(3)
Payment to buyout capital leases						(9.6)		(0.9)
Payment to buyout lease financing arrangements						(10.2)		(12.8)
Debt issuance costs						(1.3)	(5.4)	(5.2)
Payment of debt extinguishment costs							(0.8)
Contributions from/(distributions to) parent, net	0.2					0	0	0
Net cash provided by (used in) by financing activities	(0.4)					275.8	463.2	60.8
Net (decrease) increase in cash and cash equivalents	(4.2)					136.5	(22.2)	(112.3)
Cash and cash equivalents at beginning of period	16.5		36.5		148.8	12.3	36.5	148.8	16.5
Cash and cash equivalents at end of period	12.3	14.3		36.5		148.8	14.3	36.5	148.8
Supplemental disclosures
Capitalized interest							6.1	4.6	1.6
Successor
Cash flows from operating activities:
Net loss						(15.6)	(20.2)	(14.5)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization						89.9	141.5	118
Provision for bad debt write off						0.4	0	0.8
Asset impairments and loss on disposal						2.8	13.5	0
Loss on extinguishment of debt						1.3	0	13.6
Non-cash interest expense						4	3.4	3.4
Deferred income tax expense, including valuation allowance change						0.6	0	0
Stock-based compensation expense						6	14.4	10.3
Changes in operating assets and liabilities:
Rent receivables and other assets						(15.7)	(23.9)	(37)
Accounts payable and accrued expenses						(14.6)	7	6.9
Deferred revenues						(0.1)	5.4	9.8
Due to affiliates						18.4	(0.9)	(0.2)
Other						0	0	0
Net cash provided by operating activities						77.4	140.2	111.1
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate						(48)	(17.3)	0
Capital expenditures – other development						(172.9)	(217.2)	(284.2)
Business acquisition, net of cash acquired						0	(398.4)	0
Changes in restricted cash						4.4	7.3	0
Other						(0.2)	0	0
Net cash used in investing activities						(216.7)	(625.6)	(284.2)
Cash flows from financing activities:
Issuance of common stock						360.5	799.5	356
Stock issuance costs						0	(0.8)	(1.3)
IPO costs						(26.6)	0	0
Acquisition of operating partnership units						0	(596.4)	(355.9)
Dividends paid						(31)	(80.8)	(50.9)
Borrowings from credit facility						0	260	315
Payments on credit facility						0	(10)	(30)
Payments on senior notes						0	0	(150.2)
Proceeds from issuance of debt						0	103.8	0
Payments on capital lease obligations						(5.3)	(2.6)	(3)
Payments on lease financing arrangements						(0.7)	(3.3)	(0.9)
Payment to buyout capital leases						(9.6)	0	0
Payment to buyout lease financing arrangements						(10.2)	0	0
Debt issuance costs						(1.3)	(5.4)	(5.2)
Payment of debt extinguishment costs						0	0	(12.8)
Tax payment upon exercise of equity awards						0	(0.8)	0
Contributions from/(distributions to) parent, net						0	0	0
Net cash provided by (used in) by financing activities						275.8	463.2	60.8
Net (decrease) increase in cash and cash equivalents						136.5	(22.2)	(112.3)
Cash and cash equivalents at beginning of period			$ 36.5		$ 148.8	12.3	36.5	148.8
Cash and cash equivalents at end of period	12.3	$ 14.3		$ 36.5		148.8	14.3	36.5	148.8
Supplemental disclosures
Cash paid for interest, net of amount capitalized						40.7	43.7	41.3
Cash paid for income taxes						0	3.4	0.4
Capitalized interest						1.6	6.1	4.6
Noncash investing and financing transactions:
Acquisition of property in accounts payable and other liabilities						35.8	59.2	26.8
Contribution receivable from Parent related to transaction-related compensation						0	0	0
Dividends payable						10.4	23.6	14.3
Deferred IPO costs						0	0	0
Deferred IPO costs reclassified to additional paid in capital						9.5	0	0
Reclass of equipment to held for sale						0.3	0	0
Noncash additions to fixed assets through lease financing arrangements						4	$ 0	$ 0
Predecessor
Cash flows from operating activities:
Net loss	(20.2)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	5.3
Provision for bad debt write off	0
Asset impairments and loss on disposal	0
Loss on extinguishment of debt	0
Non-cash interest expense	0.1
Deferred income tax expense, including valuation allowance change	0.3
Stock-based compensation expense	0.2
Changes in operating assets and liabilities:
Rent receivables and other assets	(9.6)
Accounts payable and accrued expenses	20.5
Deferred revenues	3.2
Due to affiliates	1.5
Other	0.7
Net cash provided by operating activities	2
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate	0
Capital expenditures – other development	(7.7)
Business acquisition, net of cash acquired	0
Changes in restricted cash	1.9
Other	0
Net cash used in investing activities	(5.8)
Cash flows from financing activities:
Issuance of common stock	0
Stock issuance costs	0
IPO costs	0
Acquisition of operating partnership units	0
Dividends paid	0
Borrowings from credit facility	0
Payments on credit facility	0
Payments on senior notes	0
Proceeds from issuance of debt	0
Payments on capital lease obligations	(0.6)
Payments on lease financing arrangements	0
Payment to buyout capital leases	0
Payment to buyout lease financing arrangements	0
Debt issuance costs	0
Payment of debt extinguishment costs	0
Tax payment upon exercise of equity awards	0
Contributions from/(distributions to) parent, net	0.2
Net cash provided by (used in) by financing activities	(0.4)
Net (decrease) increase in cash and cash equivalents	(4.2)
Cash and cash equivalents at beginning of period	16.5					$ 12.3			$ 16.5
Cash and cash equivalents at end of period	12.3
Supplemental disclosures
Cash paid for interest, net of amount capitalized	0.3
Cash paid for income taxes	0
Capitalized interest	0
Noncash investing and financing transactions:
Acquisition of property in accounts payable and other liabilities	15.7
Contribution receivable from Parent related to transaction-related compensation	19.6
Dividends payable	0
Deferred IPO costs	1.7
Deferred IPO costs reclassified to additional paid in capital	0
Reclass of equipment to held for sale	0
Noncash additions to fixed assets through lease financing arrangements	$ 0

Description of Business

Description of Business	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	Description of Business CyrusOne Inc., together with CyrusOne GP, a wholly owned subsidiary of CyrusOne Inc., through which CyrusOne Inc. holds a controlling interest in CyrusOne LP (operating partnership) and the subsidiaries of the operating partnership (collectively, “CyrusOne”, “we”, “us”, “our”, and the “Company”) is an owner, operator and developer of enterprise-class, carrier-neutral multi-tenant data center properties. Our customers operate in a number of industries, including energy, oil and gas, mining, medical, technology, finance and consumer goods and services. We currently operate 32 data centers and 2 recovery centers located in the United States, United Kingdom and Singapore.

Formation and Recent Developmen

Formation and Recent Developments	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Formation and Recent Developments	Formation and Recent Developments Formation Prior to November 20, 2012, CyrusOne was not an operative legal entity or a combination of legal entities. The accompanying combined financial statements of CyrusOne for such periods represent the data center assets and operations owned by Cincinnati Bell Inc. (CBI) and, unless the context otherwise requires, its consolidated subsidiaries which historically have been maintained in various legal entities, some of which had significant unrelated business activities. The accompanying financial statements for such periods have been “carved out” of CBI’s consolidated financial statements and reflect significant assumptions and allocations. The combined financial statements do not fully reflect what the financial position, results of operations and cash flows would have been had these operations been a stand-alone company during the periods presented. As a result, historical financial information is not necessarily indicative of CyrusOne’s future results of operations, financial position and cash flows. On November 20, 2012, the operating partnership received a contribution of interests in real estate properties and the assumption of debt and other specified liabilities from CBI in exchange for the issuance of 123.7 million operating partnership units to CBI. On January 24, 2013, CyrusOne Inc. completed its initial public offering (the IPO) of common stock, issuing approximately 19 million shares for $337.1 million , net of underwriting discounts. At that time the operating partnership executed a 2.8 to 1.0 reverse unit split, resulting in CBI owning 44.1 million operating partnership units. In addition, CBI exchanged approximately 1.5 million of its operating partnership units for 1.5 million shares of CyrusOne Inc. common stock, and CBI was issued 0.4 million shares of CyrusOne Inc. common stock in repayment for transaction costs paid by CBI. CyrusOne Inc. also issued approximately 1.1 million shares of restricted stock to its directors and employees. In addition, on January 24, 2013, CyrusOne Inc. purchased approximately 21.9 million , or 33.9% of the operating partnership’s units for $337.1 million and assumed the controlling interest in the operating partnership. CBI retained a noncontrolling interest in the operating partnership of 66.1% . Recent Developments On June 25, 2014, CyrusOne Inc. completed a public offering of 16 million shares of its common stock, including 2.1 million shares of common stock issued upon the exercise in full by the underwriters of their option to purchase additional shares, at a price to the public of $23.25 per share, or $371.7 million . CyrusOne Inc. used the proceeds of $355.9 million , net of underwriting discounts of $15.8 million , to acquire 16 million common units of limited partnership interests in the operating partnership from CBI. On April 7, 2015, CyrusOne Inc. completed a public offering of approximately 14.3 million shares of its common stock, including approximately 1.9 million shares of common stock issued upon the exercise in full by the underwriters of their option to purchase additional shares, at a price to the public of $31.12 per share, or $443.8 million . CyrusOne Inc. used the proceeds of $426.0 million , net of underwriting costs of $17.8 million , to acquire approximately 14.3 million common units of limited partnership interests in the operating partnership from CBI. On June 26, 2015, CyrusOne Inc. completed a public offering of approximately 13.0 million shares of its common stock, at a price to the public of $30.00 per share, or $373.3 million , net of underwriting costs of $16.6 million . On July 1, 2015, CyrusOne used the $170.3 million to acquire approximately 6.0 million common units of limited partnership interests in the operating partnership from a subsidiary of CBI. During 2015, the Company issued $0.2 million of common shares related to the employee stock purchase plan. In total, offerings of common stock in 2015 resulted in $799.5 million of cash flow from financing activities on the consolidated and combined statements of cash flows. On July 1, 2015, CyrusOne LP acquired Cervalis for approximately $398.4 million , excluding transaction related expenses.Cervalis operates four data center facilities and two work area recovery facilities serving the New York metropolitan area On December 14, 2015, CyrusOne Inc. completed a public secondary offering of 1,350,000 shares of common stock on behalf of CBI. The Company received no proceeds from the offering. On December 31, 2015, CyrusOne Inc. completed an issuance of approximately 6.3 million newly issued shares of common stock in exchange for an equal number of operating partnership units of CyrusOne LP, held by a subsidiary of CBI. As of December 31, 2015 , CyrusOne Inc. owned 100% of the 72.6 million outstanding partnership units of CyrusOne LP. As of December 31, 2015 , CBI owned approximately 9.5% of the outstanding shares of common stock of CyrusOne Inc.

Basis of Presentation

Basis of Presentation	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements for the period ended January 23, 2013 were prepared on a combined basis using CBI’s historical basis in the assets and liabilities of its data center business and are presented as the “Predecessor” financial statements. The Predecessor financial statements include all revenues, costs, assets and liabilities directly attributable to the data center business. In addition, certain expenses reflected in the Predecessor financial statements include allocations of corporate expenses from CBI, which in the opinion of management are reasonable but do not necessarily reflect what CyrusOne’s financial position, results of operations and cash flows would have been had CyrusOne been a stand-alone company during this period. The financial statements as of December 31, 2015 and 2014 and for the period from January 24, 2013 to December 31, 2013, and the years ended December 31, 2015 and December 31, 2014, are prepared on a consolidated basis and are presented as the “Successor” financial statements. In addition, the accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP). All material intercompany transactions and balances have been eliminated in consolidation. All prior year amounts have been presented to conform to current year's presentation.

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies Use of Estimates —Preparation of the consolidated and combined financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated and combined financial statements and accompanying notes. These estimates and assumptions are based on management’s knowledge of current events and actions that we may undertake in the future. Estimates are used in determining the fair value of leased real estate, the useful lives of real estate and other long-lived assets, future cash flows associated with goodwill and other long-lived asset impairment testing, deferred tax assets and liabilities and loss contingencies. Estimates were also utilized in the determination of historical allocations of shared employees’ payroll, benefits and incentives and management fees between CyrusOne and CBI. Actual results may differ from these estimates and assumptions. Investment in Real Estate —Investment in real estate consist of land, buildings, improvements and integral equipment utilized in our data center operations. Real estate acquired from third parties has been recorded at its acquisition cost. Real estate acquired from CBI and its affiliates has been recorded at its historical cost basis. Additions and improvements which extend an asset’s useful life or increase its functionality are capitalized and depreciated over the asset’s remaining life. Maintenance and repairs are expensed as incurred. When we are involved in the construction of structural improvements to leased property, we are deemed the accounting owner of the leased real estate. In these instances, we bear substantially all the construction period risk, including managing or funding construction. As we have substantially all of the construction risks, we are deemed the “owner” of the asset under construction for accounting purposes during the construction period, and are therefore required to capitalize the construction costs on the accompanying consolidated balance sheets. At inception, the fair value of the building (excluding land) is recorded as an asset and the construction and modification costs to the building, that are not funded by us would be recorded as a liability. As construction progresses, the value of the asset and obligation increases by the fair value of the structural improvements. At completion of the construction, Sales-Leaseback Accounting under ASC 840-40-25 is also evaluated. Due to our continuing involvement with the lessor, Sales-Leaseback Accounting is precluded and the liability is not derecognized. When the asset is placed in service, depreciation commences, and the leased real estate is depreciated to the lesser of (i) its estimated fair value at the end of the term or (ii) the expected amount of the unamortized obligation at the end of the term. The associated obligation is presented as lease financing arrangements in the accompanying consolidated balance sheets. When we are not deemed the accounting owner of leased real estate, we further evaluate the lease to determine whether the lease should be classified as a capital or operating lease. One of the following four characteristics must be present to classify a lease as a capital lease: (i) the lease transfers ownership of the property to the lessee by the end of the lease term, (ii) the lease contains a bargain purchase option, (iii) the lease term is equal to 75% or more of the estimated economic life of the leased property or (iv) the net present value of the lease payments are at least 90% of the fair value of the leased property. Construction in progress includes direct and indirect expenditures for the construction and expansion of our data centers and is stated at its acquisition cost. Independent contractors perform substantially all of the construction and expansion efforts of our data centers. Construction in progress includes costs incurred under construction contracts including project management services, engineering and schematic design services, design development, construction services and other construction-related fees and services. Interest, property taxes and certain labor costs are also capitalized during the construction of an asset. Capitalized interest in 2015 , 2014 , and 2013 was $6.1 million , $4.6 million , and $1.6 million , respectively. These costs are depreciated over the estimated useful life of the related assets. Depreciation is calculated using the straight-line method over the estimated useful life of the asset. Useful lives range from nine to thirty years for buildings, three to thirty years for building improvements, and three to twenty years for equipment. Leasehold improvements are amortized over the shorter of the asset’s useful life or the remaining lease term, including renewal options which are reasonably assured. Management reviews the carrying value of long-lived assets, including intangible assets with finite lives, when events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. Examples of such indicators may include a significant adverse change in the extent to which or manner in which the property is being used, an accumulation of costs significantly in excess of the amount originally expected for acquisition or development, or a history of operating or cash flow losses. When such indicators exist, we review an estimate of the undiscounted future cash flows expected to result from the use of an asset (or group of assets) and its eventual disposition and compare such amount to its carrying amount. We consider factors such as future operating income, leasing demand, competition and other factors. If our undiscounted net cash flows indicate that we are unable to recover the carrying value of the asset, an impairment loss is recognized. An impairment loss is measured as the amount by which the asset’s carrying value exceeds its estimated fair value. For the years ended December 31, 2015 and 2013, we recognized impairments and loss on disposal of $13.5 million and $2.8 million , respectively. Cash and Cash Equivalents —Cash and cash equivalents include all non-restricted cash held in financial institutions and other non-restricted highly liquid short-term investments with original maturities at acquisition of three months or less. Restricted Cash —Restricted cash includes cash equivalents held to collateralize standby letters of credit and/or deposited in escrow to fund construction or pending potential acquisition transactions. In addition, we may have other cash that is not immediately available for use in current operations. Goodwill —Goodwill represents the excess of the purchase price over the fair value of net assets acquired in connection with business acquisitions. We perform impairment testing of goodwill, at the reporting unit level, on an annual basis or more frequently if indicators of potential impairment exist. The fair value of our reporting unit was determined using a combination of market-based valuation multiples for comparable businesses and discounted cash flow analysis based on internal financial forecasts incorporating market participant assumptions. There were no impairments recognized for the years ended December 31, 2015 or 2014. Long-Lived and Intangible Assets —Intangible assets represent purchased assets that lack physical substance, but can be separately distinguished from Goodwill because of contractual or other legal rights or because the asset is capable of being sold or exchanged, either on its own or in combination with a related contract, asset, or liability. Intangible assets with finite lives consist of trademarks, customer relationships, and a favorable leasehold interest. Rent and Other Receivables —Receivables consist principally of trade receivables from customers and are generally unsecured and due within 30 to 120 days . Unbilled receivables arise from services rendered but not yet billed. Expected credit losses associated with trade receivables are recorded as an allowance for uncollectible accounts. The allowance for uncollectible accounts is estimated based upon historic patterns of credit losses for aged receivables as well as specific provisions for certain identifiable, potentially uncollectible balances. When internal collection efforts on receivables have been exhausted, the receivables are written-off and the associated allowance for uncollectible accounts is reduced. The Company has receivables with one customer that exceeds 10% of the Company’s outstanding accounts receivable balance at December 31, 2015 and 2014 . In addition, as of December 31, 2015 , our receivables include $6.5 million that has not been billed to the customer. This amount will be billed and payable in monthly installments through March 2018. Deferred Leasing Costs —Deferred leasing costs are presented with Other assets in the accompanying consolidated balance sheets. Leasing commissions incurred at the commencement of a new lease are capitalized and amortized over the term of the customer lease. Amortization of deferred leasing costs is presented with Depreciation and amortization in the accompanying consolidated and combined statements of operations. If a lease terminates prior to the expiration of the lease, the remaining unamortized cost is written off to amortization expense. As of December 31, 2015 and 2014, deferred leasing costs were $14.2 million and $12.8 million , respectively. Deferred Financing Costs —Deferred financing costs include costs incurred in connection with issuance of debt, including 6.375% senior notes, term loans and revolving credit facilities. These financing costs are capitalized and amortized to expense over the term of the instrument and are included as a component of Interest expense. These costs include deferred financing costs associated with our revolving line of credit and are presented in the balance sheet as a direct reduction from the carrying amount of the debt liability to conform to the 2015 presentation. 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 —Colocation rentals are generally billed monthly in advance, and some contracts have escalating payments over the term of the contract. If rents escalate without the lessee gaining access to or control over additional leased space or power, and the lessee takes possession of, or controls the physical use of the property (including all contractually committed power) at the beginning of the lease term, the rental payments by the lessee are recognized as revenue on a straight-line basis over the term of the lease. If rents escalate because the lessee gains access to and control over additional leased space or power, revenue is recognized in proportion to the additional space or power in the periods that the lessee has control over the use of the additional space or power. The excess of revenue recognized over amounts contractually due is recognized in Other assets in the accompanying consolidated balance sheets. As of December 31, 2015 and 2014, straight-line rent receivable was $44.7 million and $33.7 million , respectively. Some of our leases are structured on a full-service gross basis in which the customer pays a fixed amount for both colocation rent and power. Other leases provide that the customer will be billed for power based upon actual usage times a load factor. Power is generally billed one month in arrears and an estimate of this revenue is accrued in the month that the associated costs are incurred. We generally are not entitled to reimbursements for real estate taxes, insurance or other operating expenses. Revenue is recognized for services or products that are deemed separate units of accounting. When a customer makes an advance payment or they are contractually obligated to pay any amounts in advance, which is not deemed a separate unit of accounting, Deferred revenue is recorded. This revenue is recognized ratably over the expected term of the lease, unless the pattern of service suggests otherwise. As of December 31, 2015 and 2014 , Deferred revenue was $78.7 million and $65.7 million , respectively. Certain customer leases require specified levels of service or performance. If we fail to meet these service levels, our customers may be eligible to receive credits on their contractual billings. These credits are recognized against revenue when an event occurs that gives rise to such credits. Customer credits were immaterial for each of the years presented. A provision for uncollectible accounts is recognized when the collection of contractual rent, straight-line rent or customer reimbursements are deemed to be uncollectible. Sales and Marketing Expense —Sales and marketing expense is comprised of compensation and benefits associated with Sales and marketing personnel as well as advertising and marketing costs. Costs related to advertising are expensed as incurred and amounted to $2.2 million for the year ended December 31, 2015, $2.9 million for the year ended December 31, 2014, $2.1 million for the period ended December 31, 2013, and $0.1 million for the period ended January 23, 2013. Depreciation and Amortization Expense —Depreciation expense is recognized over the estimated useful lives of real estate applying the straight-line method. The useful life of leased real estate and leasehold improvements is the lesser of the economic useful life of the asset or the term of the lease, including optional renewal periods if renewal of the lease is reasonably assured. The residual value of leased real estate is estimated as the lesser of (i) the expected fair value of the asset at the end of the lease term or (ii) the expected amount of the unamortized liability at the end of the lease term. Estimated useful lives are periodically reviewed. Depreciation expense was $117.8 million for the year ended December 31, 2015, $95.8 million for the year ended December 31, 2014, $70.3 million for the period ended December 31, 2013, and $4.1 million for the period ended January 23, 2013. Amortization expense is recognized over the estimated useful lives of finite-lived intangibles. Finite-lived intangibles include trademarks, favorable leasehold interests, deferred leasing costs and deferred sales commissions. As of December 31, 2015, the estimated weighted average useful life of trademarks and customer relationships was ten and 13 years, respectively. In addition, we have a favorable leasehold interest related to a land lease that is being amortized over the lease term of fifty-one years. Deferred leasing costs are amortized over three to five years . Amortization expense was $23.7 million for the year ended December 31, 2015, $22.2 million for the year ended December 31, 2014, $19.6 million for the period ended December 31, 2013, and $1.2 million for the period ended January 23, 2013 . Transaction and Acquisition Integration Costs —Transaction costs represent incremental legal, accounting and professional fees incurred in connection with our formation transactions, our initial qualification as a real estate investment trust, or REIT, and business combination and asset acquisition costs (including unsuccessful efforts). Transaction costs are expensed as incurred and do not include any recurring costs from our ongoing operations. Integration costs represent incremental costs to integrate a consummated acquisition. Transaction-Related Compensation —During the period ended January 23, 2013, the Company received an allocated compensation charge from CBI of $20.0 million for the settlement of its long-term incentive plan associated with the completion of the IPO. The amount was determined by CBI and allocated to CyrusOne Inc. on January 23, 2013, and reflected as expense and contributed capital in the respective period. Income Taxes —CyrusOne Inc. was included in CBI’s consolidated tax returns in various jurisdictions for the Predecessor period and was included in the Successor period for Texas only until June 26, 2014 when CBI's ownership percentage in the operating partnership was reduced below 50%. In the accompanying financial statements, the Predecessor period and the Successor period (for Texas only until June 26, 2014) reflect income taxes as if the Company were a separate stand-alone company. The income tax provision consists of an amount for taxes currently payable and an amount for tax consequences deferred to future periods. CyrusOne Inc. elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (Code), commencing with our initial taxable year ending December 31, 2013. Provided we continue to meet the various qualification tests mandated under the Code, we are generally not subject to corporate level federal income tax on the earnings distributed currently to our shareholders. If we fail to qualify as a REIT in any taxable year, our taxable income will be subject to federal income tax at regular corporate rates and any applicable alternative minimum tax. While CyrusOne Inc. and the operating partnership do not pay federal income taxes, we are still subject to foreign, state and local income taxes in the locations in which we conduct business. Our taxable REIT subsidiaries (each a TRS) are also subject to federal and state income taxes to the extent they earn taxable income. Deferred income taxes are recognized in certain entities. Deferred income taxes are provided for temporary differences in the bases between financial statement and income tax assets and liabilities. Deferred income taxes are recalculated annually at rates then in effect. Valuation allowances are recorded to reduce deferred tax assets to amounts that are more likely than not to be realized. The ultimate realization of the deferred tax assets depends upon our ability to generate future taxable income during the periods in which basis differences and other deductions become deductible and prior to the expiration of the net operating loss carryforwards. The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction as well as various state, local and foreign jurisdictions. The Company's previous tax filings are subject to normal reviews by regulatory agencies until the related statute of limitations expires. With a few exceptions, the Company is no longer subject to U. S. federal, state or local examinations for years prior to 2012, and we have no liabilities for uncertain tax positions as of December 31, 2015 or 2014. Foreign Currency Translation and Transactions —The financial position of foreign subsidiaries is translated at the exchange rates in effect at the end of the period, while revenues and expenses are translated at average rates of exchange during the period. Gains or losses from translation of foreign operations where the local currency is the functional currency are included as components of other comprehensive (loss) income. Gains or losses from foreign currency transactions are included in determining net income. Comprehensive Loss —Comprehensive loss represents the change in net assets of a company from transactions and other events from non-owner sources. Comprehensive loss comprises all components of net loss and all components of other comprehensive loss. Subsequent to the issuance of the Company’s 2014 consolidated financial statements, the Company identified an error in the Consolidated Statements of Comprehensive Income (Loss) and the Consolidated Balance Sheets and Statements of Equity. The Consolidated Statements of Comprehensive Income (Loss) excluded allocations of net loss attributable to noncontrolling interests and only attributed foreign currency translation adjustment allocations to the noncontrolling interest. This error resulted in the understatement of “Comprehensive Loss Attributable to Non-Controlling Interests” of ($6.7) million for the year ended December 31, 2014 (Successor), and ($10.3) million for the Successor period ended December 31, 2013, as well as the corresponding understatement of the total “Comprehensive Loss Attributable to CyrusOne Inc.”. The Consolidated Statements of Equity did not present the comprehensive loss attributed to foreign currency translation adjustment allocations to noncontrolling interest. This error resulted in “Foreign Currency Translation Adjustment” allocated to CyrusOne Inc. to be overstated and the amount allocated to Noncontrolling Interest to be understated by $0.1 million for the year ended December 31, 2014 (Successor) and “Accumulated Other Comprehensive Loss” and “Noncontrolling Interest” to be overstated by $0.1 million as of December 31, 2014 (Successor), which resulted in a corresponding overstatement in the Consolidated Balance Sheets. The prior period amounts disclosed above have been revised to reflect the corrected amounts. The previously issued Consolidated Statement of Operations and Cash Flows were not impacted by this error. Earnings Per Share —For all periods subsequent to January 23, 2013, we present earnings per share (EPS) data. Basic EPS includes only the weighted average number of common shares outstanding during the period. Diluted EPS includes the weighted average number of common shares and the dilutive effect of stock options, restricted stock and share unit awards outstanding during the period, when such instruments are dilutive. All outstanding unvested share-based payment awards that contain rights to nonforfeitable dividends are treated as participating in undistributed earnings with common shareholders. Awards of this nature are considered participating securities and the two-class method of computing basic and diluted EPS must be applied. Related Party Transactions —CBI provided us with a variety of services. Cost allocation methods which were employed to determine the costs to be recognized in the accompanying combined financial statements included the following: • Specific identification—Applied when amounts were specifically identifiable to our operations. • Reasonable allocation method—When amounts were not clearly or specifically identifiable to our operations, management applied a reasonable allocation method. Stock-Based Compensation —In conjunction with the IPO, our board of directors adopted the 2012 Long-Term Incentive Plan (LTIP). The LTIP is administered by the compensation committee of the board of directors, or the plan administrator. Awards issuable under the LTIP include common stock, restricted stock, stock options and other incentive awards. See Note 16 to our audited consolidated and combined financial statements included elsewhere in this Annual Report on Form 10-K for additional details relating to these awards. Share-based compensation expense is based on the estimated grant-date fair value. CyrusOne Inc. recognizes share-based compensation expense, less estimated forfeitures, on a straight-line basis over the requisite service period for time-based awards and on a graded vesting basis for performance-based awards. CyrusOne estimates forfeitures based on historical activity, expected employee turnover, and other qualitative factors which are adjusted for changes in estimates and award vesting. All expenses for an award will be recognized by the time it becomes fully vested. CyrusOne Inc. uses the Black-Scholes-Merton option pricing model to calculate the fair value of stock options. This option valuation model requires the use of subjective assumptions, including the estimated fair value of the underlying common stock, the expected stock price volatility, and the expected term of the option. The estimated fair value of the underlying common stock is based on third-party valuations. Our volatility estimates are based on a peer group of companies. We estimate the expected term of the awards to be the weighted average mid-point between the vesting date and the end of the contractual term. We use this method to estimate the expected term since we do not have sufficient historical exercise data. For interim periods, we use our year-to-date actual results, financial forecasts, and other available information to estimate the probability of the award vesting based on the performance metrics. Fair Value Measurements —Fair value measurements are utilized in accounting for business combinations and testing of goodwill and other long-lived assets for impairment and disclosures. Fair value of financial and non-financial assets and liabilities is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. The three-tier hierarchy for inputs used in measuring fair value, which prioritizes the inputs used in the methodologies of measuring fair value for asset and liabilities, is as follows: Level 1—Observable inputs for identical instruments such as quoted market prices; Level 2—Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs); and Level 3—Unobservable inputs that reflect our determination of assumptions that market participants would use in pricing the asset or liability. These inputs are developed based on the best information available, including our own data. Business Segments —Business segments are components of an enterprise for which separate financial information is available and regularly viewed by the chief operating decision maker to assess performance and allocate resources. Our chief operating decision maker, the Company's Chief Executive Officer, reviews our financial information on an aggregate basis. Furthermore, our data centers have similar economic characteristics and customers across all geographic locations, our service offerings have similar production processes, deliver services in a similar manner and use the same types of facilities and similar technologies. As a result, we have concluded that we have one reportable operating segment.

Recently Issued Accounting Stan

Recently Issued Accounting Standards	12 Months Ended
	Dec. 31, 2015
Accounting Changes and Error Corrections [Abstract]
Recently Issued Accounting Standards	Recently Issued Accounting Standards Accounting Standards Update (ASU) No. 2014-09 (ASU 2014-09), Revenue from Contracts with Customers (Topic 606) In May 2014, the Financial Accounting Standards Board (FASB) issued guidance that outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most of the existing revenue recognition guidance. This guidance requires an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services and also requires certain additional disclosures which are effective for interim and annual reporting periods in fiscal years that begin after December 15, 2016. In July 2015, the FASB voted to approve a one-year deferral of the effective date to December 15, 2017 for interim and annual reporting periods beginning after that date and permitted early adoption of the standard, but not before the original effective date of December 15, 2016. This guidance permits two implementation approaches. Companies can chose to apply the standard retrospectively to each prior reporting period presented (full retrospective application) or retrospectively with the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings of the annual reporting period that includes the date of initial application (modified retrospective application). We are currently evaluating the impact of the adoption of this guidance in our consolidated financial statements. ASU No. 2014-12 (ASU 2014-12), Compensation-Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved After the Requisite Service Period In June 2014, the FASB issued a guidance update for the presentation of stock compensation. This guidance requires an entity to treat performance targets that can be met after the requisite service period of a share based award has ended, as a performance condition that affects vesting and is effective for interim and annual reporting periods in fiscal years that begin after December 15, 2015. Since the Company's share-based awards do not contain performance targets that could be achieved after the employee completes the requisite service, the adoption of this guidance has no impact on our consolidated financial statements. ASU No. 2014-15 (ASU 2014-15), Presentation of Financial Statements - Going Concern (Subtopic 205-40) In August 2014, the FASB issued guidance on determining when and how reporting entities must disclose going-concern uncertainties in their financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date of issuance of the entity’s financial statements. This guidance is effective for annual periods ending after December 15, 2016, and interim periods thereafter; early adoption is permitted. We are currently evaluating the full impact of the new standard. ASU No. 2015-01 (ASU 2015-01), Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items In January 2015, the FASB issued guidance eliminating from U.S. GAAP the concept of an extraordinary item. An entity is no longer required to (1) segregate an extraordinary item from the results of ordinary operations; (2) separately present an extraordinary item on its income statement, net of tax, after income from continuing operations; and (3) disclose income taxes and earnings-per-share data applicable to an extraordinary item. This guidance does not affect the reporting and disclosure requirements for an event that is unusual in nature or that occurs infrequently. ASU No. 2015-02 (ASU 2015-02), Consolidation (Topic 810) In February 2015, the FASB issued guidance which amended the consolidation requirements in ASC 810 and significantly changed the consolidation analysis required under U.S. GAAP. The amendments include (1) limited partnerships will be variable interest entities; (2) changes the effect that fees paid to a decision maker or service provider have on the consolidation analysis; (3) amends how variable interests held by a reporting entity's related parties or de facto agents affect its consolidation conclusion; (4) clarifies how to determine whether the equity holders have power over the entity, and (5) the deferral of ASU 2009-17 for investments in certain investment funds has been eliminated. This guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. The adoption of this guidance will have no impact on our consolidated financial statements as the provisions of this standard do not currently apply to CyrusOne Inc. ASU No. 2015-03 (ASU 2015-03), Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued guidance to simplify the presentation of debt issuance costs. The amendments would require that debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of debt liability, consistent with debt discounts or premiums. The recognition and measurement guidance for debt issuance costs would not be affected by this guidance. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted this standard and debt issuance costs for all periods presented have been shown as a reduction from the carrying amount of the debt. ASU No. 2015-15 (ASU 2015-15), Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements In August 2015, the FASB issued ASU 2015-15 to clarify the SEC staff's position on presenting and measuring debt issuance costs incurred in connection with line-of-credit arrangements given the lack of guidance on this topic in ASU 2015-03. The SEC staff has announced that it would not object to an entity deferring issuance costs ratably over the term of the line-of-credit arrangement. The Company ratably expenses the debt issuance costs over the term of its revolving line of credit and reflects any unamortized amount as a reduction from the carrying amount of its debt. ASU No. 2015-16 (ASU 2015-16), Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments In September 2015, the FASB issued ASU 2015-16 to simplify the accounting for measurement-period adjustments. Under the ASU, an acquirer must recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The ASU also requires acquirers to present separately on the face on the income statement, or disclose in the notes, the portion of the amount recorded in the current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. This guidance is effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The adoption of this standard is not expected to have a material impact on our consolidated financial statements. ASU No. 2015-17 (ASU 2015-17), Income Taxes (Topic 740) In November 2015, the FASB issued guidance which amended the balance sheet classification requirements for deferred Taxes. The ASU requires an entity to classify all deferred tax liabilities and assets as noncurrent in the balance sheet. This guidance is effective for financial statements issued for annual periods beginning after December 15, 2016, including interim periods within those fiscal years. We are currently evaluating the full impact of the new standard. ASU No. 2016-01 (ASU 2016-01), Financial instruments-Overall (Subtopic 825-10) In January 2016, the FASB amended its standards related to the accounting of certain financial instruments. This amendment addresses certain aspects of recognition, measurement, presentation and disclosure. The new rules will become effective for annual and interim periods beginning after December 15, 2017. Early adoption is not permitted. We are in the process of evaluating the impact the amendment will have on the consolidated financial statements. ASU No. 2016-02 (ASU 2016-02), Leases (Topic 842) In February 2016, the FASB issued accounting standard update (“ASU”) No. 2016-02, Leases (Topic 842). This new lease guidance requires that an entity should recognize assets and liabilities for leases with a maximum possible term of more than 12 months. A lessee would recognize a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the leased asset (the underlying asset) for the lease term. Leases would be classified as either Type A leases (generally today’s capital leases) or Type B leases (generally today’s operating leases). For certain leases of assets other than property (for example, equipment, aircraft, cars, trucks), a lessee would classify the lease as a Type A lease and would do the following: (1) recognize a right-of-use asset and a lease liability, initially measured at the present value of lease payments and (2) recognize the unwinding of the discount on the lease liability as interest separately from the amortization of the right-of-use asset. For certain leases of property (that is, land and/or a building or part of a building), a lessee would classify the lease as a Type B lease and would do the following: (1) recognize a right-of-use asset and a lease liability, initially measured at the present value of lease payments and (2) recognize a single lease cost, combining the unwinding of the discount on the lease liability with the amortization of the right-of-use asset, on a straight-line basis. This guidance also provides accounting updates with respect to lessor accounting under a lease arrangement. This new lease guidance is effective for CyrusOne beginning in the first quarter of fiscal 2019. Entities have the option of using either a full retrospective or a modified approach (cumulative effect adjustment in period of adoption) to adopt the new guidance. Early adoption is permitted for all entities. We are currently evaluating the impact of the adoption of this guidance in our consolidated financial statements.”

Acquisitions

Acquisitions	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Acquisitions	Acquisitions On July 1, 2015, CyrusOne LP acquired 100% of Cervalis, a privately-held owner and operator of data centers for $398.4 million , excluding transaction-related expenses, in an all cash transaction. Cervalis has four data center facilities and two work recovery facilities serving the New York metropolitan area. CyrusOne LP financed the acquisition with proceeds of CyrusOne Inc's June 2015 common stock offering and CyrusOne LP and CyrusOne Finance Corp.'s July 2015 6.375% senior notes offering as well as drawing under CyrusOne Inc's senior unsecured credit facility. The acquisition of Cervalis enhances the geographic diversification of CyrusOne, provides access to a high quality enterprise customer base and strengthens our product portfolio. The goodwill recorded for this acquisition relates to the incremental value that Cervalis brings to the existing CyrusOne operations. The customer relationships intangible is expected to be amortized over fifteen years . For the year ended December 31, 2015, transaction and integration costs related to the Cervalis Acquisition were $12.9 million . The consolidated and combined financial statements include the operating results of Cervalis from the date of acquisition. The following table summarizes the estimated fair values of all assets acquired and liabilities assumed at the date of acquisition: Cash $ 1.1 Rent and other receivables 10.5 Restricted cash 8.8 Net investment in real estate 197.8 Goodwill 177.2 Customer relationships 117.4 Trade name 2.3 Other long-term assets 7.3 Total assets acquired 522.4 Current liabilities 18.3 Capital lease obligations 1.7 Long-term debt 1.5 Other arrangements 101.4 Total liabilities 122.9 Net assets acquired attributable to CyrusOne Inc. 399.5 Cash acquired (1.1 ) Net cash paid at acquisition 398.4 The acquisition of Cervalis in July 2015 resulted in an increase in revenue of $37.7 million for year ended December 31, 2015. The unaudited pro forma combined historical results of CyrusOne, as if Cervalis had been acquired and the financing transactions had been consummated as of January 1, 2014 are: IN MILLIONS For the year ended December 31, 2015 2014 Revenue 438.6 399.0 Net loss (10.9 ) (17.2 ) Loss per share - basic and diluted (0.16 ) (0.35 ) These amounts have been calculated after applying CyrusOne's policies and adjusting the results to reflect changes to Depreciation and amortization to property and equipment, amongst others, and amortizing intangible assets had been recorded as of January 1, 2014. These pro forma combined results of operation are presented for informative purposes only and they do not purport to be indicative of the results of operation that actually would have resulted had the acquisition occurred on the date indicated, or that may result in the future.

Investment in Real Estate

Investment in Real Estate	12 Months Ended
	Dec. 31, 2015
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, 2015 2014 Land Building and Equipment Land Building and Equipment West Seventh St., Cincinnati, OH (7th Street) $ 0.9 $ 110.6 $ 19.6 $ 0.9 $ 110.6 $ 12.7 Parkway Dr., Mason, OH (Mason) — 20.2 1.0 — 20.2 0.9 Industrial Rd., Florence, KY (Florence) 2.2 41.5 3.3 2.2 41.4 3.0 Goldcoast Dr., Cincinnati, OH (Goldcoast) 0.6 6.7 0.1 0.6 6.7 0.1 Knightsbridge Dr., Hamilton, OH (Hamilton) — 49.2 4.4 — 49.2 3.7 E. Monroe St., South Bend, IN (Monroe St.) — 2.5 0.3 — 2.5 0.1 Springer St., Lombard, IL (Lombard) 0.7 4.7 7.6 0.7 4.7 5.7 Crescent Circle, South Bend, IN (Blackthorn) — 3.3 0.4 — 3.3 0.1 Kingsview Dr., Lebanon, OH (Lebanon) 4.0 77.3 7.6 4.0 77.0 5.5 McAuley Place, Blue Ash, OH (Blue Ash) — 0.6 0.1 — 0.6 0.1 Westway Park Blvd., Houston, TX (Houston West 1) 1.4 84.8 46.4 1.4 84.4 43.8 Westway Park Blvd., Houston, TX (Houston West 2) 2.0 22.6 47.1 2.0 22.5 45.1 Westway Park Blvd., Houston, TX (Houston West 3) 18.4 4.0 0.8 18.4 — — Southwest Fwy., Houston, TX (Galleria) — 68.6 16.0 — 68.6 15.0 E. Ben White Blvd., Austin, TX (Austin 1) — 13.6 1.0 — 22.5 1.2 S. State Highway 121 Business, Lewisville, TX (Lewisville) — 76.6 24.9 — 76.7 22.8 Marsh Lane, Carrollton, TX (Marsh Ln) — 0.1 0.6 — 0.1 0.5 Midway Rd., Carrollton, TX (Midway) — 2.0 0.4 — 2.0 0.4 W. Frankford Rd., Carrollton, TX (Carrollton) 16.1 52.7 116.5 16.1 51.6 85.3 Bryan St., Dallas, TX (Bryan St) — — — — 0.1 0.2 North Freeway, Houston, TX (Greenspoint) — — — — 1.3 — South Ellis Street, Chandler, AZ (Phoenix 1) 14.8 56.7 39.8 14.8 56.4 43.9 South Ellis Street, Chandler, AZ (Phoenix 2) — 16.0 39.5 — 13.2 21.8 Westover Hills Blvd., San Antonio, TX (San Antonio 1) 4.6 32.1 33.0 4.6 32.1 32.4 Westover Hills Blvd., San Antonio, TX (San Antonio 2) 7.0 — 0.1 7.0 — — Metropolis Dr., Austin, TX (Austin 2) 2.0 23.2 5.7 2.0 23.2 4.0 Myer Conners Rd (Wappinger Falls) — 11.3 14.4 — — — Madison Road (Totowa) — 28.3 48.8 — — — Commerce Road (Totowa) — 4.1 1.0 — — — Norden Place (Norwalk) — 18.3 25.4 — — — Riverbend Drive South (Stamford) — 4.3 13.2 — — — Omega Drive (Stamford) — 3.2 1.5 — — — Kestral Way (London) — 31.2 0.8 — 32.7 0.7 Jurong East (Singapore) — 8.4 0.1 — 9.0 0.1 Ridgetop Circle, Sterling, VA (Northern Virginia) 7.0 19.2 45.2 7.0 — — Metropolis Dr., Austin, TX (Austin 3) 8.0 — 0.1 8.0 — — Metropolis Dr., Austin, TX (Austin 4) 3.3 7.4 31.5 — — — Total $ 93.0 $ 905.3 $ 598.2 $ 89.7 $ 812.6 $ 349.1 In addition, Construction in progress was $231.1 million and $127.0 million as of December 31, 2015 and December 31, 2014 , respectively, as we continue to build data center facilities. For the year ended December 31, 2015, our capital expenditures were $17.3 million for the purchase of Austin 4 facility and $217.2 million for other development as shown on the consolidated and combined statements of cash flows. The significant items included the development of additional square footage and power in our Northern Virginia, Phoenix 2, Houston West 3 and Carrollton data centers, and the purchase of Austin 4 in February of 2015. The total purchase price of the Austin 4 facility was $17.3 million , of which $3.3 million was allocated to Land and the remaining amount remains in Construction in progress as of December 31, 2015. For the year ended December 31, 2015, we recognized Asset impairment and loss on disposal of $ 13.5 million which related primarily to the exit of Austin 1, which is a leased facility, and loss on disposal of certain other assets.

Goodwill, Intangible and Other

Goodwill, Intangible and Other Long-Lived Assets	12 Months Ended
	Dec. 31, 2015
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 $453.4 million and $276.2 million as of December 31, 2015 and 2014 . As of December 31, 2015, the amounts recognized for Goodwill and Intangible assets were in connection with the acquisition of Cyrus Networks as well as prior acquisitions, as described in Note 2, Formation and Recent Developments. For the year ended December 31, 2015, the additions to Goodwill, customer relationships, trade name and favorable leasehold interest related to the acquisition of Cervalis which were $177.2 million , $117.4 million , $2.3 million and $0.2 million , respectively. Summarized below are the carrying values for the major classes of intangible assets: IN MILLIONS For the year ended December 31, 2015 2014 Weighted- Gross Carrying Amount Accumulated Amortization Total Gross Carrying Amount Accumulated Amortization Total Customer relationships 13 $ 247.1 $ (87.5 ) $ 159.6 $ 129.7 $ (69.5 ) $ 60.2 Trademark 10 7.4 (2.7 ) 4.7 7.4 (2.3 ) 5.1 Favorable leasehold interest 49 4.1 (0.4 ) 3.7 3.9 (0.3 ) 3.6 Trade name (not amortized) 2.3 — 2.3 — — — Total $ 260.9 $ (90.6 ) $ 170.3 $ 141.0 $ (72.1 ) $ 68.9 There were no goodwill or intangible asset impairments for the years ended December 31, 2015 or 2014. Amortization expense for acquired intangible assets subject to amortization was $18.5 million , $17.0 million , $15.9 million and $1.0 million for the years ended December 31, 2015 and 2014, for the period ended December 31, 2013, and for the period ended January 23, 2013, respectively. The following table presents estimated amortization expense for each of the next five years and thereafter, commencing January 1, 2016: IN MILLIONS 2016 $ 19.4 2017 17.3 2018 15.4 2019 13.8 2020 12.6 Thereafter 89.5 Total $ 168.0

Debt and Other Financing Arrang

Debt and Other Financing Arrangements	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt and Other Financing Arrangements	Debt, Capital Lease Obligations and Lease Financing Arrangements Debt, Capital lease obligations and Lease financing arrangements presented in the accompanying consolidated and combined financial statements consist of the following: IN MILLIONS For the year ended December 31, 2015 2014 Credit facilities: Revolving credit facility $ 235.0 $ 135.0 Term loan 300.0 150.0 6.375% senior notes due 2022, including bond premium 477.6 374.8 Notes Payable 1.5 — Deferred financing costs (17.6 ) (15.5 ) Long-term debt 996.5 644.3 Capital lease obligations 12.2 13.4 Lease financing arrangements 150.0 53.4 Total $ 1,158.7 $ 711.1 Credit Facility —On October 9, 2014, CyrusOne LP entered into a credit agreement which provided for a $450 million senior unsecured revolving credit facility to replace CyrusOne LP's $225 million secured credit facility, and a $150 million senior unsecured term loan. On June 22, 2015, CyrusOne entered into an amendment to the Credit Agreement and other loan documents governing its revolving credit facility and term loan facility. The amendment increased the size of the Credit Agreement's accordion feature, which gave the operating partnership the ability to request an increase in the total commitment under the Credit Agreement, from $300 million to $600 million . Immediately after entering into the amendment, the operating partnership exercised $350 million of this accordion feature and obtained commitments to increase the total commitment under the Credit Agreement from $600 million to $950 million , comprised of $650 million of commitments under the revolving credit facility and $300 million under the term loan. In addition, the Credit Agreement contains an accordion feature that allows CyrusOne LP to increase the aggregate commitment by up to $250 million . The revolving credit facility is scheduled to mature in October 2018 and includes a one -year extension option, which if exercised by CyrusOne LP would extend the maturity date to October 2019. The term loan is scheduled to mature in October 2019. The revolving credit facility currently bears interest at a rate per annum equal to LIBOR plus 1.70% and the term loan currently bears interest at a rate per annum equal to LIBOR plus 1.65% . As of December 31, 2015 there were borrowings of $235.0 million under the revolving credit facility and $300.0 million under the term loan. As of December 31, 2014 there were borrowings of $135 million under the revolving credit facility and $150 million under the term loan. There were no borrowings under the previous credit agreement as of December 31, 2013. We pay commitment fees for the unused amount of borrowings on the revolving credit facility and term loan and letter of credit fees on any outstanding letters of credit. The commitment fees are equal to 0.25% per annum of the actual daily amount by which the aggregate revolving commitments exceed the sum of outstanding revolving loans and letter of credit obligations. Commitment fees related to the credit agreement were $0.9 million and $1.1 million for the years ended December 31, 2015 and 2014 , respectively. 6.375% Senior Notes due 2022 —On November 20, 2012, CyrusOne LP and CyrusOne Finance Corp. (Issuers) issued $525 million of 6.375% senior notes due 2022 ( 6.375% senior notes). The 6.375% senior notes are senior unsecured obligations of the Issuers, which rank equally in right of payment with all existing and future unsecured senior debt of the Issuers. The 6.375% senior notes are effectively subordinated to all existing and future secured indebtedness of the Issuers to the extent of the value of the assets securing such indebtedness. The 6.375% senior notes are fully and unconditionally and jointly and severally guaranteed by CyrusOne Inc., CyrusOne GP, and each of CyrusOne LP’s existing and future domestic wholly owned subsidiaries, subject to certain exceptions. Each such guarantee is a senior unsecured obligation of the applicable guarantor, ranking equally with all existing and future unsecured senior debt 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 6.375% senior notes are structurally subordinated to all liabilities, including trade payables, of each subsidiary of the Issuer that does not guarantee the 6.375% senior notes. The 6.375% senior notes bear interest at a rate of 6.375% per annum, payable semi-annually on May 15 and November 15 of each year, beginning on May 15, 2013. The 6.375% senior notes will mature on November 15, 2022. However, prior to November 15, 2017, the Issuers may, at their option, redeem some or all of the 6.375% senior notes at a redemption price equal to 100% of the principal amount of the 6.375% senior notes, together with accrued and unpaid interest, if any, plus a “make-whole” premium. On or after November 15, 2017, the Issuers were permitted , at our option, redeem some or all of the 6.375% senior notes at any time at declining redemption prices equal to (i) 103.188% beginning on November 15, 2017, (ii) 102.125% beginning on November 15, 2018, (iii) 101.063% beginning on November 15, 2019 and (iv) 100.000% beginning on November 15, 2020 and thereafter, plus, in each case, accrued and unpaid interest, if any, to the applicable redemption date. In addition, before November 15, 2015, and subject to certain conditions, the Issuers may, at their option, redeem up to 35% of the aggregate principal amount of the 6.375% senior notes with the net proceeds of certain equity offerings at 106.375% of the principal amount thereof, plus accrued and unpaid interest, if any, to the date of redemption; provided that (i) at least 65% of the aggregate principal amount of the 6.375% senior notes remains outstanding and (ii) the redemption occurs within 90 days of the closing of any such equity offering. In November and December of 2014, we repurchased our 6.375% senior notes with an aggregate face value of $150.2 million for a purchase price of $163 million , including accrued interest. This resulted in a loss on extinguishment of debt of $12.8 million . On July 1, 2015, the Issuers closed a private offering of $100 million aggregate principal amount of the 6.375% senior notes (New Notes) plus a premium of $3.8 million . The New Notes were issued as additional notes under the Indenture dated November 20, 2012 as supplemented by the first supplemental indenture dated July 1, 2015, and the New Notes have terms substantially identical to those of the 6.375% senior notes issued in November 2012. The Issuers and guarantors of the New Notes entered into a registration rights agreement which requires them, at their cost, to use commercially reasonably efforts to file and cause to become effective a registration statement within 180 days of July 1, 2015, to be used in connection with the exchange of the New Notes for freely tradable notes with substantially identical terms in all material respects to the New Notes (which exchange must be completed on or prior to the 30 th day after such registration statement is declared effective). On December 29, 2015, all notes issued on July 1, 2015 were exchanged for registered notes. Debt Covenants —The 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 ratio; • A maximum secured recourse indebtedness ratio; • A minimum unencumbered debt yield ratio; and • A maximum ratio of unsecured indebtedness to unencumbered asset value. Notwithstanding these limitations, we will be permitted, subject to the terms and conditions of the Credit Agreement, to distribute to our shareholders cash dividends in an amount not to exceed 95% of our Funds From Operations (FFO), as defined in the Credit Agreement) for any period. Similarly, our indenture permits dividends and distributions necessary for us to maintain our status as a REIT. The Company’s most restrictive covenants are generally included in its credit agreement. In order to continue to have access to amounts available to it under the credit agreement, the Company must remain in compliance with all covenants. The indenture governing the 6.375% senior notes contains affirmative and negative covenants customarily found in indebtedness of this type, including a number of covenants that, among other things, restrict, subject to certain exceptions, the Company’s ability to: incur secured or unsecured indebtedness; pay dividends or distributions on its equity interests, or redeem or repurchase equity interests of the Company; make certain investments or other restricted payments; enter into transactions with affiliates; enter into agreements limiting the ability of the operating partnership’s subsidiaries to pay dividends or make certain transfers and other payments to the operating partnership or to other subsidiaries; sell assets; and merge, consolidate or transfer all or substantially all of the operating partnership’s assets. Notwithstanding the foregoing, the covenants contained in the indenture do not restrict the Company’s ability to pay dividends or distributions to shareholders to the extent (i) no default or event of default exists or is continuing under the indenture and (ii) the Company believes in good faith that we qualify as a REIT under the Code and the payment of such dividend or distribution is necessary either to maintain its status as a REIT or to enable it to avoid payment of any tax that could be avoided by reason of such dividend or distribution. The Company and its subsidiaries are also required to maintain total unencumbered assets of at least 150% of their unsecured debt on a consolidated basis, provided that for the purposes of such calculation their revolving credit facility shall be treated as unsecured indebtedness, in each case subject to certain qualifications set forth in the indenture. As of December 31, 2015 , we believe we were in compliance with all covenants. Notes Payable —As of December 31, 2015, the Company had a note payable for approximately $1.5 million with a third-party for electrical infrastructure at one of the Company's locations. The note payable matures in January 2034. We will pay approximately $9,000 per month until maturity under the note payable. Deferred financing costs —Deferred financing costs are costs incurred in connection with obtaining long-term financing. Deferred financing costs were incurred in connection with the issuance of the revolving credit facility and term loan and 6.375% senior notes due 2022. As of December 31, 2015, and 2014, deferred financing costs totaled $17.6 million and $15.5 million , respectively. Deferred financing costs related to the 6.375% senior notes are amortized using the effective interest method over the term of the related indebtedness. Deferred financing costs related to the revolving credit facility and term loan are amortized using the straight-line method. Amortization of deferred financing costs, included in Interest expense in the consolidated and combined statements of operations, totaled $3.4 million , $3.4 million , $4.0 million and $0.1 million for the years ended December 31, 2015 and 2014, for the periods ended December 31, 2013, and January 23, 2013, respectively. The amortization of deferred financing costs for the year ended December 31, 2014 included $0.8 million related to the extinguishment of debt and the correction of expense recorded in prior periods. Capital lease obligations —We use leasing as a source of financing for certain of our data center facilities and related equipment. We currently operate four data center facilities subject to capital leases. We have options to extend the initial lease term on all these leases and options to purchase the facility for one of these leases. Lease financing arrangements —Lease financing arrangements represent leases of real estate in which we are involved in the construction of structural improvements to develop buildings into data centers. When we bear substantially all the construction period risk, such as managing or funding construction, we are deemed to be the accounting owner of the leased property and, at the lease inception date, we are required to record at fair value the property and associated liability on our balance sheet. These transactions generally do not qualify for sale-leaseback accounting due to our continued involvement in these data center operations. Interest expense on Capital lease obligations and Lease financing arrangements were $7.8 million , $5.9 million , $6.3 million and $0.3 million for the years ended December 31, 2015 and 2014, for the period ended December 31, 2013 and January 23, 2013, 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, 2015 , and thereafter: IN MILLIONS Future Value of Payments Interest Present Value of Payments 2016 $ 17.8 $ 8.7 $ 9.1 2017 16.8 8.3 8.5 2018 14.8 7.9 6.9 2019 15.1 7.5 7.6 2020 26.0 6.8 19.2 Thereafter 127.0 28.3 98.7 Total lease financing arrangements $ 217.5 $ 67.5 $ 150.0 The following table summarizes aggregate maturities of revolving credit facility and term loan, 6.375% senior notes due 2022 and capital leases for the five years subsequent to December 31, 2015 , and thereafter: IN MILLIONS Revolving Credit Facility/Term Loan 6.375% Senior Notes Capital Leases Total 2016 $ — $ — $ 3.1 $ 3.1 2017 — — 1.6 1.6 2018 235.0 — 1.5 236.5 2019 300.0 — 1.6 301.6 2020 — — 1.7 1.7 Thereafter — 474.8 2.7 477.5 Total debt $ 535.0 $ 474.8 $ 12.2 $ 1,022.0 The payment of interest on capital leases over the next five years and thereafter will be $1.0 million , $0.8 million , $0.7 million , $0.5 million , $0.4 million and $0.4 million , respectively.

Fair Value of Financial Instrum

Fair Value of Financial Instruments	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value of Financial Instruments	Fair Value of Financial Instruments The fair value of Cash and cash equivalents, Restricted cash, Rent and other receivables and Accounts payable and accrued expenses approximate their carrying value because of the short-term nature of these instruments. The carrying value and fair value of other financial instruments are as follows: IN MILLIONS For the year ended December 31, 2015 2014 Carrying Value Fair Value Carrying Value Fair Value 6.375% senior notes due 2022 $ 477.6 $ 493.8 $ 374.8 $ 402.0 Revolving credit facility and term loan 535.0 535.0 285.0 285.0 Note payable 1.5 1.2 — — The fair value of our 6.375% senior notes as of December 31, 2015 and 2014 was based on the quoted market price for these notes, which is considered Level 1 of the fair value hierarchy. The carrying value of the revolving credit facility and term loan approximates estimated fair value as of December 31, 2015 , due to the variability of interest rates and the stability of our credit ratings. The fair value of the note payable at December 31, 2015, was calculated using a discounted cash flow model that incorporates current borrowing rates for obligations of similar duration. These fair value measurements are considered Level 3 of the fair value hierarchy. Non-recurring fair value measurements Certain long-lived assets, intangibles and goodwill are required to be measured at fair value on a non-recurring basis subsequent to their initial measurement. These non-recurring fair value measurements generally occur when evidence of impairment has occurred. The measured fair value used in the 2013 related impairment charges is summarized below: IN MILLIONS December 31, 2013 Quoted prices in active markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) 2013 Impairment Loss Equipment $ 0.3 $ — $ 0.3 $ — $ (2.8 ) Total impairment $ (2.8 ) In the fourth quarter of 2013, we agreed to an offer to sell equipment which had a net book value of $3.1 million for $0.3 million , resulting in a loss of $2.8 million . There were no impairment charges for the year ended December 31, 2014. The Asset impairments and loss on disposal for the year ended December 31, 2015 was $13.5 million and were related to the exit from a leased facility and loss on disposal of assets.

Noncontrolling Interests - Oper

Noncontrolling Interests - Operating Partnership	12 Months Ended
	Dec. 31, 2015
Noncontrolling Interest [Abstract]
Noncontrolling Interest - Operating Partnership	Noncontrolling Interest - Operating Partnership As discussed in Note 2, Formation and Recent Developments, the noncontrolling interest represents the limited partnership interest in the operating partnership held by CBI. The following table shows the ownership interests as of December 31, 2015 and 2014, and the portion of net loss and distributions for the year ended December 31, 2015 and 2014: For the year ended December 31, 2015 2014 (in millions, except unit amount) The Company CBI The Company CBI Operating partnership units 72.6 — 38.7 26.6 Ownership % 100.0 % — % 59.2 % 40.8 % Portion of net loss $ (15.4 ) $ (4.8 ) $ (7.8 ) $ (6.7 ) Distributions $ (74.6 ) $ (16.3 ) $ (29.2 ) $ (25.7 ) Under the Amended and Restated Agreement of Limited Partnership of the operating partnership (the LP Agreement), the limited partners of the operating partnership (including CBI) have certain redemption rights. The LP Agreement grants the limited partners the right to require the operating partnership to redeem part or all of their operating partnership units for cash based upon the fair market value of an equivalent number of shares of our common stock at the time of the redemption, determined in accordance with and subject to adjustment as provided in the LP Agreement. Alternatively, at our discretion, we may elect to acquire those operating partnership units in exchange for shares of our common stock. Our acquisition of partnership units in exchange for shares of our common stock would be on a one -for-one basis, subject to adjustment in the event of stock splits, stock dividends, distributions of warrants or stock rights, specified extraordinary distributions and similar events. With each redemption or exchange, we increase our percentage ownership interest in our operating partnership. On December 31, 2015, CyrusOne Inc. issued 6,346,835 shares of its common stock, in exchange for an equal number of operating partnership units in CyrusOne LP held by a subsidiary of CBI. As a result, CBI owns approximately 9.5% of the Company’s common stock, and all of the operating partnership units in the CyrusOne LP are owned, directly or indirectly, by the Company. CyrusOne Inc. had no noncontrolling interests as of December 31, 2015 .

Dividends

Dividends	12 Months Ended
	Dec. 31, 2015
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, 2015 and 2014 as presented in the table below: Record date Payment date Cash dividend per share or operating partnership unit March 28, 2014 April 15, 2014 $0.21 June 27, 2014 July 15, 2014 $0.21 September 26, 2014 October 15, 2014 $0.21 December 26, 2014 January 9, 2015 $0.21 March 27, 2015 April 15, 2015 $0.315 June 26, 2015 July 15, 2015 $0.315 September 25, 2015 October 15, 2015 $0.315 December 24, 2015 January 8, 2016 $0.315 As of December 31, 2015 and 2014 we had a dividend payable of $24.4 million and $14.3 million , respectively. On February 23, 2016 , we announced a regular cash dividend of $0.38 per common share payable to shareholders of record as of March 25, 2016. The dividend will be paid on April 15, 2016.

Customer Leases

Customer Leases	12 Months Ended
	Dec. 31, 2015
Leases [Abstract]
Customer Leases	Customer Leases Customer lease arrangements customarily contain provisions that allow either for renewal or continuation on a month-to-month arrangement. Certain leases contain early termination rights. At lease inception, early termination is generally not deemed reasonably assured due to the significant economic penalty incurred by the lessee to exercise its termination right and to relocate its equipment. The future minimum lease payments to be received under non-cancellable operating leases, excluding month-to-month arrangements and submetered power, for the next five years are shown below: IN MILLIONS 2016 $ 379.4 2017 295.0 2018 204.1 2019 121.6 2020 81.2

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [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 $3.1 million and $2.1 million of expenses related to these plans for the years ended December 31, 2015 and 2014, respectively. For the periods ended December 31, 2013 and January 23, 2013, we incurred $1.6 million and $0.1 million , respectively, of expenses related to these plans. CyrusOne offers a retirement savings plan to its employees. CyrusOne's matching contribution to its retirement savings plan was $1.1 million and $0.8 million for the years ended December 31, 2015 and December 31, 2014 , respectively, less than $0.5 million for the period ended December 31, 2013, and less than $0.1 million for the period ended January 23, 2013.

Loss per Share

Loss per Share	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Loss per Share	Loss Per Share Basic loss per share is calculated using the weighted average number of shares of common stock outstanding during the period. In addition, net loss applicable to participating securities and the related participating securities are excluded from the computation of basic loss per share. Diluted 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. The following table reflects a reconciliation of the shares used in the basic and diluted net loss per share computation: IN MILLIONS, except per share amounts Year Ended Year Ended Period Ended For December 31, 2015 2014 2013 Basic Diluted Basic Diluted Basic Diluted Numerator: Net loss attributed to common shareholders $ (15.4 ) $ (15.4 ) $ (7.8 ) $ (7.8 ) $ (5.3 ) $ (5.3 ) Less: Restricted stock dividends (1.0 ) (1.0 ) (0.8 ) (0.8 ) (0.6 ) (0.6 ) Net loss available to shareholders $ (16.4 ) $ (16.4 ) $ (8.6 ) $ (8.6 ) $ (5.9 ) $ (5.9 ) Denominator: Weighted average common outstanding-basic 54.3 54.3 29.2 29.2 20.9 20.9 Performance-based restricted stock (1)(2)(3) — — — Convertible securities (1)(2)(3) — — — Weighted average shares outstanding-diluted 54.3 29.2 20.9 EPS: Net loss per share-basic $ (0.30 ) $ (0.30 ) $ (0.28 ) Effect of dilutive shares — — — Net loss per share-diluted $ (0.30 ) $ (0.30 ) $ (0.28 ) (1) We have excluded 1.9 million weighted average shares of restricted stock, and 13.1 million of weighted average operating partnership units which are securities convertible into common stock from our diluted earnings per share as of December 31, 2015 . These amounts were deemed anti-dilutive. (2) We have excluded 0.8 million weighted average shares of restricted stock, and 34.3 million of weighted average operating partnership units which are securities convertible into common stock from our diluted earnings per share as of December 31, 2014. These amounts were deemed anti-dilutive. (3) We have excluded 0.2 million weighted average shares of restricted stock, and 42.6 million of weighted average operating partnership units which are securities convertible into common stock from our diluted earnings per share as of December 31, 2013. These amounts were deemed anti-dilutive.

Stock-Based Compensation Plans

Stock-Based Compensation Plans	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Stock-Based Compensation Plans	Stock-Based Compensation Plans Stock-based compensation expense was as follows: For the periods ended December 31, 2015 2014 2013 Founders $ 5.2 $ 5.4 $ 5.3 2013 Grants 1.2 1.2 0.9 2014 Grants 3.0 3.7 — 2015 Grants 5.0 — — Total $ 14.4 $ 10.3 $ 6.2 In conjunction with the CyrusOne Inc. IPO, the board of directors of CyrusOne Inc. adopted the 2012 Long-Term Incentive Plan (LTIP). The LTIP is administered by the board of directors. Awards issuable under the LTIP include common stock, restricted stock, stock options and other incentive awards. CyrusOne Inc. has reserved a total of 4 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, 2015, were approximately 1.5 million . Shares vest according to each agreement and as long as the employee remains employed with the Company. The Company uses the Black-Scholes option-pricing model for time and performance-based options and a Monte Carlo simulation for market-based awards. 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. 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. Holders of the restricted stock have all of the rights and privileges of shareholders including but not limited to the right to vote, receive dividends and distributions upon liquidation of CyrusOne. These shares vest at the end of three years. As of December 31, 2015, unearned compensation representing the unvested portion of the Founders awards, net of forfeitures, totaled $0.3 million , and the weighted average vesting period was 0.1 years. 2013 Grants On April 17, 2013, the Company issued performance and market-based awards under the LTIP in the form of stock options and restricted stock units. For these awards, vesting was tied 50% to the achievement of a non-GAAP performance measure (cumulative EBITDA targets, as defined in the agreement), over the 2013-2015 performance period, and 50% market-based performance measure (the total stockholder return (TSR), as defined in the agreement) at the end of the three -year period ending December 31, 2015. The portion of the awards tied to cumulative EBITDA was eligible to vest annually over a three -year period based on the Company attaining predetermined cumulative EBITDA targets. 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 = 0% - At 90% of performance target = 50% - At 100% of performance target = 100% - At or above 115% of performance target = up to 200% The portion of the awards tied to TSR was eligible to vest at the end of three years if the TSR, during the three -year measurement period following the grant date, met or exceeded the return of the MSCI US REIT Index (Index) over the same period. The TSR targets are 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 Index = 0% - If CyrusOne's TSR is equal to or greater than the return of the Index = 100% ; up to 200% if CyrusOne's TSR exceeds the return of the Index by 2% - If CyrusOne's TSR exceeds the return of the Index, but is negative, any calculated vesting amount will be reduced by 50% 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 . In addition, during the year ended December 31, 2013, the Company also granted from time-to-time a total of 4,361 additional time-based restricted shares which had an aggregate value of $0.1 million on the grant date. These shares cliff vested one year after the grant date or will vest three years after the grant date. The holders of restricted stock shall have all of the rights and privileges of shareholders including the right to vote. Any dividends paid with respect to the shares shall be accrued by the Company and distributed on the vesting date provided that the applicable performance goal has been attained. As of December 31, 2015, unearned compensation representing the unvested portion of the awards granted during 2013 (excluding the Founders awards), net of forfeitures, totaled $0.1 million , with a weighted average vesting period of 0.3 years. 2014 Grants On February 7, 2014, the Company issued performance and market-based awards under the LTIP in the form of restricted stock units. For these awards, vesting is tied 50% to the achievement of a non-GAAP performance measure (cumulative Adjusted EBITDA targets, as defined in the agreement) over the 2014-2016 performance period, and 50% to a market-based performance measure TSR, as defined in the agreement), as of the end of the three-year period ending December 31, 2016. The portion of the awards tied to cumulative Adjusted EBITDA vest annually over a three -year period based on the Company attaining predetermined cumulative Adjusted EBITDA targets and as long as the employee remains employed with the Company. The portion of the award tied to TSR will vest at the end of three years based on the cumulative TSR over a three -year performance period. The market and performance-based awards will vest based on the same scales as the awards granted during 2013. 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 will vest three years after the grant date. The holders of restricted stock have all of the rights and privileges of shareholders including the right to vote. Any dividends paid with respect to the shares shall be accrued by the Company and distributed on the vesting date provided that the applicable performance goal has been attained. As of December 31, 2015, unearned compensation representing the unvested portion of the awards granted during 2014, net of forfeitures, totaled $1.3 million , with a weighted average vesting period of 1.1 years. 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-five percent of the restricted stock awards are subject to time-based vesting and seventy-five percent of the restricted stock awards are equally split between performance-based and market-based vesting. The time-based restricted stock will vest pro-rata annually over three years . The performance and market-based restricted stock will vest annually based upon the achievement of certain criteria for each year of the three -year measurement period. The first two years are capped at 100% of the target with a cumulative true-up in year three. The fair values of these awards were determined using the Black-Scholes or Monte-Carlo model which use assumptions such as volatility, risk-free interest rate, and expected term of the awards. In addition, during the year ended December 31, 2015, for various new employee hires, the following grants were made: • 8,157 shares of time-based restricted stock which cliff vest in three years from the date of each grant. • 29,424 shares of time-based restricted stock which vest annually from the date of each grant. • 12,719 time-based options which vest annually from the date of each grant. • 11,711 shares of performance-based restricted stock, which vest annually based upon the achievement of certain criteria for each year of the three -year measurement period. • 55,301 shares of performance-based (separate non-GAAP measure, as defined in the specific agreement) restricted stock, which cliff vests in three years from the date of grant. For the year ended December 31, 2015, the unvested portion of the awards granted in 2015, net of forfeitures, totaled $5.6 million and the weighted average vesting period was 1.6 years. 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. Restricted Stock and Stock Option Activity The following table summarizes the unvested restricted stock activity and the weighted average fair value of these shares at the date of grant for the year ended December 31, 2015: For the year ended December 31, 2015 Shares Weighted Average Grant Date Fair Value Non-vested at January 1 1,739,642 $ 20.20 Granted 571,224 23.80 Vested (458,606 ) 20.90 Forfeited (266,779 ) 21.80 Non-vested at December 31 1,585,481 $ 20.99 The non-vested shares were 1,739,642 and 1,126,669 at December 31, 2014 and 2013, respectively. The following table summarizes the stock option activity for the year ended December 31, 2015: For the year ended December 31, 2015 Options Weighted Average Exercise Price Outstanding at January 1 166,872 $ 23.58 Granted 223,186 28.44 Exercised (2,525 ) 23.58 Forfeited or expired (53,554 ) 25.98 Outstanding at December 31 333,979 26.44 Exercisable at December 31 78,806 25.75 Vested and expected to vest 78,806 $ 25.75 The outstanding options were 166,872 and 168,963 at December 31, 2014 and 2013, respectively. 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 fiscal year 2015 was immaterial. There were no options exercised during 2014 and 2013. The aggregate intrinsic value of options outstanding at December 31, 2015 was $3.7 million . The aggregate intrinsic value of options exercisable at December 31, 2015 was $0.9 million . Stock Option Assumptions The following table summarizes the stock option assumptions for the years ended December 31, 2015, 2014, and 2013: 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 2013 $23.58 168,963 9.3 — 0.0 0.92% 3.4% 6.0 35% 2014 $23.58 166,872 8.3 13,915 8.3 0.92% 3.4% 6.0 35% 2015 $23.58 142,556 7.3 43,460 7.3 0.92% 3.4% 6.0 35% $28.42 178,704 9.1 35,346 9.1 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $30.74 12,719 9.6 — 0.0 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5%

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Prior to November 20, 2012, CyrusOne Inc., CyrusOne GP, CyrusOne LP and its subsidiaries were operated by CBI. The consolidated and combined financial statements have been prepared from the records maintained by CBI and may not necessarily be indicative of the conditions that would have existed or the results of operations that would have occurred if the business had been operated as an unaffiliated company. The consolidated and combined financial statements reflect the following transactions with CBI and its affiliated entities, including Cincinnati Bell Telephone (CBT) and Cincinnati Bell Technology Solutions (CBTS). Revenues —The Company records revenues from CBI under contractual service arrangements. These services include leasing of data center space, power and cooling in certain of our data center facilities network interface services and office space. Operating Expenses —The Company records expenses from CBI incurred in relation to network support, services calls, monitoring and management, storage and backup, IT systems support, and connectivity services. The following related party transactions are based on agreements and arrangements that were in place during the respective periods. Revenues and expenses for the periods presented were as follows: IN MILLIONS Successor Predecessor December 31, 2015 December 31, 2014 January 24, 2013 to December 31, 2013 January 1, 2013 to January 23, 2013 Revenue: Data center colocation agreement provided to CBT and CBTS $ 7.8 $ 6.4 $ 5.6 $ 0.3 229 West 7th Street lease provided to CBT 1.9 2.0 1.7 — Goldcoast Drive/Parkway (Mason) lease 0.3 0.4 0.3 — Transition services provided to CBTS (network interfaces) 0.3 0.4 0.6 0.1 Data center leases provided to CBTS 12.0 13.6 13.1 — Total revenue $ 22.3 $ 22.8 $ 21.3 $ 0.4 Operating costs and expenses: Transition services agreement by CBTS $ 0.7 $ 0.8 $ 1.3 $ — Charges for services provided by CBT (connectivity) 1.0 1.0 1.0 0.1 209 West 7th Street rent provided by CBT 0.2 0.2 0.1 — Management fees with CBI — — 0.1 — Allocated employee benefit plans by CBI — — — 0.2 Allocated centralized insurance costs by CBI — — — 0.1 Total operating costs and expenses $ 1.9 $ 2.0 $ 2.5 $ 0.4 As of December 31, 2014, the amounts receivable and payable to CBI were as follows: IN MILLIONS As of December 31, 2014 Accounts receivable from CBI $ 0.8 Accounts payable $ 1.7 Dividends payable 5.6 Total payable to CBI $ 7.3 The dividends payable as of December 31, 2015 , was approximately $2.0 million , which relates to the 6.3 million operating partnership units in CyrusOne LP held by a subsidiary of CyrusOne Inc. as of the record date of December 24, 2015. As of December 31, 2015, CBI was no longer an affiliate of CyrusOne Inc. as described in Note 2, Formation and Recent Developments. Other Related Party Transactions Prior to joining CyrusOne in March 2013, our former general counsel Thomas Bosse was principal in the Law Offices of Thomas W. Bosse, PLLC, (Bosselaw). In 2013, amounts paid to Bosselaw for services rendered prior to his employment were $1.6 million , which included a bonus payment under CyrusOne’s Data Center Plan as a result of the successful completion of the IPO. In the ordinary course of its business, CyrusOne periodically pays brokerage commissions to real estate brokerage firms in connection with property transactions and tenant leases. In 2015, 2014 and 2013, CyrusOne paid $1.1 million , $1.0 million and $1.5 million , respectively, to one such firm, Jones Lang LaSalle. One of our former directors is a principal with Jones Lang LaSalle. The spouse of one of our former directors is a partner with Skadden, Arps, Slate, Meagher & Flom LLP (Skadden). For the years ended December 31, 2014 and 2013, CyrusOne paid Skadden $1.1 million and $0.2 million , respectively, for services rendered. In 2015, the amount CyrusOne paid to Skadden was immaterial. Our director, Lynn A. Wentworth, is a member of the board of directors of CBI, and serves as the chair of its audit and finance committee.

Restructuring Charges

Restructuring Charges	12 Months Ended
	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring Charges	Restructuring Charges For the period ended December 31, 2013, we incurred restructuring charges of $0.7 million that were a result of moving certain administrative functions to the corporate office. All restructuring charges were settled by December 31, 2014.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
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 taxable income distributed currently to our shareholders. It is our policy and intent, subject to change, to distribute 100% of our taxable income and therefore no provision is required in the accompanying financial statements for federal income taxes with regards to activities of CyrusOne Inc. and its subsidiary pass-through entities. We have elected to designate two subsidiaries as taxable REIT subsidiaries (each a TRS). A TRS may perform services for our tenants that would otherwise be considered impermissible for REITs. The income generated from these services is taxed at federal and state corporate rates. While CyrusOne Inc. and the operating partnership do not pay federal income taxes, we are still subject to foreign, state, and local income taxes in the locations in which we conduct business. Income tax expense for the year ended December 31, 2015 and December 31, 2014, and for the periods ended December 31, 2013 and January 23, 2013 was $1.8 million , $1.4 million , $1.9 million and $0.4 million , respectively. In conjunction with the Company’s tax sharing arrangement with CBI, CBI may be required to file Texas margin tax returns on a consolidated, combined or unitary basis with the Company for any given year. If such return is prepared by CBI on a combined or consolidated basis to include the Company, the related Texas margin tax of the Company will be paid by CBI. The Company will then reimburse CBI for its portion of the related Texas margin tax. Our total Texas margin tax payable was $ 0.0 million and $1.7 million as of December 31, 2015 and 2014, respectively. For certain entities we calculate deferred tax assets and liabilities for temporary differences in the basis between financial statement and income tax assets and liabilities. Deferred income taxes are recalculated annually at rates then in effect. Valuation allowances are recorded to reduce deferred tax assets to amounts that are more likely than not to be realized. The ultimate realization of the deferred tax assets depends upon our ability to generate future taxable income during the periods in which basis differences and other deductions become deductible and prior to the expiration of the net operating loss carryforwards. Deferred tax assets (net of valuation allowance) and liabilities were accrued, as necessary, for the periods ended December 31, 2015, and December 31, 2014. Historically, we have recorded a full valuation allowance on our foreign net deferred tax assets related to our foreign generated net operating losses due to the uncertainty of their realization. In 2013 and 2014, management determined it was necessary to record a full valuation allowance on all of our domestic and foreign net deferred tax assets due to the uncertainty of their realization. Accordingly, at December 31, 2015 and at December 31, 2014, the net domestic and foreign deferred tax assets were zero . In 2015 and 2014, we paid all our dividends in cash. The following table summarizes the taxability of our common stock dividends per share for the year ended December 31, 2015 and December 31, 2014: For the year ended December 31, 2015 2014 Common Stock dividend per share: Ordinary income $ — $ 0.45 Return of capital 1.16 0.34 Total dividend $ 1.16 $ 0.79 Common stock dividends may be characterized for federal income tax purposes as ordinary income, qualified dividends, capital gains, non-taxable return of capital or a combination of the four. Common stock dividends that exceed our current and accumulated earnings and profits (calculated for tax purposes) constitute a return of capital rather than a dividend and generally reduce the stockholder's basis in the common stock. To the extent that a dividend exceeds both current and accumulated earnings and profits and the stockholder's basis in the common stock, it will generally be treated as gain from the sale or exchange of that stockholder's common stock. At the beginning of each year, we notify our stockholders of the taxability of the common stock dividends paid during the preceding year.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
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 $7.4 million , $6.7 million , $6.5 million and $0.2 million for the years ended December 31, 2015 , and December 31, 2014 , and the period ended December 31, 2013 and January 23, 2013, respectively. Certain of these leases provide for renewal options with fixed rent escalations beyond the initial lease term. At December 31, 2015 , 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 2016 $ 4.3 2017 4.2 2018 1.8 2019 — 2020 — Thereafter 0.9 Total $ 11.2 Standby Letters of Credit As of December 31, 2015 , CyrusOne Inc. had outstanding letters of credit of $7.1 million as security for obligations under the terms of the lease 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, 2015 and 2014 , no accruals for performance guarantees were required. Indemnifications During the normal course of business, CyrusOne has made certain indemnities, commitments and guarantees under which it 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 negligence or willful misconduct and (iii) indemnities involving the representations and warranties in certain contracts. 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 CyrusOne has non-cancellable purchase commitments for certain services and contracts related to construction of data center facilities and equipment. 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, 2015 , the minimum commitments for these arrangements were approximately $42.6 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, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Guarantors	Guarantors CyrusOne Inc. CyrusOne LP and CyrusOne Finance Corp., as “LP Co-issuer” and “Finance Co-issuer,” respectively (together, the Issuers), had $477.6 million aggregate principal amount of 6.375% senior notes outstanding, including bond premium, at December 31, 2015 . As of December 31, 2015 , the 6.375% senior notes are fully and unconditionally and jointly and severally guaranteed on a senior basis by CyrusOne Inc. (Parent Guarantor), CyrusOne GP (General Partner), and CyrusOne LP’s wholly owned subsidiaries, CyrusOne LLC, CyrusOne TRS Inc., CyrusOne Foreign Holdings LLC, Cervalis Holdings LLC, and Cervalis LLC (such subsidiaries, together the Guarantors). None of CyrusOne LP's subsidiaries organized outside of the United States (collectively, the Non-Guarantors) guarantee the 6.375% senior notes. Subject to the provisions of the indenture governing the 6.375% senior 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 indenture, • 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 indenture, • if such Guarantor is no longer a guarantor or other obligor of any other indebtedness of the LP Co-issuer or the Parent Guarantor, and • upon the defeasance or discharge of the 6.375% senior notes in accordance with the terms of the indenture. The entity structure of each guarantor of the 6.375% senior notes is described below. CyrusOne Inc. – CyrusOne Inc. was formed on July 31, 2012. As of January 23, 2013, CyrusOne Inc. was a wholly owned subsidiary of CBI. Effective January 24, 2013 , CyrusOne Inc. completed its IPO of common stock for net proceeds of $337.1 million , and together with the General Partner, purchased a 33.9% ownership interest in CyrusOne LP. CyrusOne Inc. is a guarantor or Parent Guarantor and became a separate registrant with the SEC upon completion of its IPO. CyrusOne GP – CyrusOne GP was formed on July 31, 2012, and was a wholly owned subsidiary of CyrusOne Inc. as of January 23, 2013 . Effective upon completion of CyrusOne Inc.’s IPO, this entity became the general partner and 1% owner of CyrusOne LP and has no other assets or operations. Prior to the IPO, this entity did not incur any obligations or record any transactions. Issuers – The Issuers are CyrusOne LP and CyrusOne Finance Corp. CyrusOne Finance Corp., a wholly owned subsidiary of CyrusOne LP, was formed for the sole purpose of acting as co-issuer of the 6.375% senior notes and has no other assets or operations. CyrusOne LP, in addition to being the co-issuer of the 6.375% senior notes, is also the 100% owner, either directly or indirectly, of the Guarantors and Non-Guarantors. Guarantor Subsidiaries – The guarantors of the 6.375% senior notes include CyrusOne LLC, CyrusOne TRS Inc., CyrusOne Foreign Holdings LLC, Cervalis and Cervalis LLC (the Guarantor Subsidiaries) agreed to provide unconditional guarantees of the issuers’ obligations under the 6.375% senior notes. The guarantee of each Guarantor Subsidiary is (i) a senior unsecured obligation of such Guarantor Subsidiary, (ii) pari passu in right of payment with any existing and future unsecured senior indebtedness of such Guarantor Subsidiary, (iii) senior in right of payment to any future subordinated indebtedness of such Guarantor Subsidiary and (iv) effectively subordinated in right of payment to all existing and future secured indebtedness of such Guarantor Subsidiary, to the extent of the value of the collateral securing that indebtedness. CyrusOne LLC, together with CyrusOne Foreign Holdings LLC, directly or indirectly owns 100% of the Non-Guarantors. Non-Guarantors consist of wholly owned subsidiaries which conduct operations in the United Kingdom and Singapore, as well as CyrusOne Government Services LLC, a Delaware limited liability company and 100% owned subsidiary. The following schedules present the balance sheets as of December 31, 2015 and 2014, and the statements of operations and comprehensive income (loss) for the years ended December 31, 2015 and 2014 and the periods ended December 31, 2013 and January 23, 2013, and the statements of cash flows for the years ended December 31, 2015 and 2014 and the periods ended December 31, 2013 and January 23, 2013 for the Parent Guarantor, General Partner, LP Co-issuer, Finance Co-issuer, Guarantors, and Non-Guarantors. The financial statements for the period ended January 23, 2013, present the financial information prior to the effective date of the IPO, and the financial statements for the period ended December 31, 2013, present the financial information after the effective date of the IPO. The consolidating schedules are provided in accordance with the reporting requirements for guarantor subsidiaries. The condensed consolidating statements of cash flows for the year ended December 31, 2015 , includes the acquisition of Cervalis in July 2015. The results for Cervalis are included in the Guarantor financial statements subsequent to the Cervalis Acquisition. Consolidating Balance Sheets IN MILLIONS As of December 31, 2015 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Land $ — $ — $ — $ — $ 93.0 $ — $ — $ 93.0 Buildings and improvements — — — — 865.6 39.6 0.1 905.3 Equipment — — — — 594.7 0.9 2.6 598.2 Construction in progress — — — — 229.8 0.1 1.2 231.1 Subtotal — — — — 1,783.1 40.6 3.9 1,827.6 Accumulated depreciation — — — — (426.0 ) (9.6 ) — (435.6 ) Net investment in real estate — — — — 1,357.1 31.0 3.9 1,392.0 Cash and cash equivalents — — — — 10.4 3.9 — 14.3 Investment in subsidiaries 817.7 8.2 850.6 — 0.7 — (1,677.2 ) — Restricted cash — — — — 1.5 — — 1.5 Rent and other receivables — — — — 74.8 1.3 — 76.1 Intercompany receivable — — 991.3 — — — (991.3 ) — Goodwill — — — — 453.4 — — 453.4 Intangible assets, net — — — — 170.3 — — 170.3 Due from affiliates — — — — — — — — Other assets — — — — 85.3 2.7 — 88.0 Total assets $ 817.7 $ 8.2 $ 1,841.9 $ — $ 2,153.5 $ 38.9 $ (2,664.6 ) $ 2,195.6 Accounts payable and accrued expenses $ — $ — $ 29.2 — $ 106.8 $ 0.6 $ — $ 136.6 Deferred revenue — — — — 78.0 0.7 — 78.7 Intercompany payable — — — — 991.3 — (991.3 ) — Due to affiliates — — — — — — — — Capital lease obligations — — — — 6.1 6.1 — 12.2 Long-term debt — — 995.0 — 1.5 — — 996.5 Lease financing arrangements — — — — 119.2 30.8 — 150.0 Total liabilities — — 1,024.2 — 1,302.9 38.2 (991.3 ) 1,374.0 Total shareholders' equity 817.7 8.2 817.7 — 850.6 0.7 (1,673.3 ) 821.6 Noncontrolling interest — — — — — — — — Total equity 817.7 8.2 817.7 — 850.6 0.7 (1,673.3 ) 821.6 Total liabilities and equity $ 817.7 $ 8.2 $ 1,841.9 $ — $ 2,153.5 $ 38.9 $ (2,664.6 ) $ 2,195.6 IN MILLIONS As of December 31, 2014 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Land $ — $ — $ — $ — $ 89.7 $ — $ — $ 89.7 Buildings and improvements — — — — 770.9 41.7 — 812.6 Equipment — — — — 348.3 0.8 — 349.1 Construction in progress — — — — 124.8 — 2.2 127.0 Subtotal — — — — 1,333.7 42.5 2.2 1,378.4 Accumulated depreciation — — — — (319.7 ) (7.3 ) — (327.0 ) Net investment in real estate — — — — 1,014.0 35.2 2.2 1,051.4 Cash and cash equivalents — — — — 33.5 3.0 — 36.5 Investment in subsidiaries 458.5 7.1 734.3 — 3.6 — (1,203.5 ) — Rent and other receivables — — — — 57.9 3.0 — 60.9 Intercompany receivable — — 642.9 — — — (642.9 ) — Goodwill — — — — 276.2 — — 276.2 Intangible assets, net — — — — 68.9 — — 68.9 Due from affiliates — — — — 0.8 — — 0.8 Other assets — — — — 73.1 3.2 — 76.3 Total assets $ 458.5 $ 7.1 $ 1,377.2 $ — $ 1,528.0 $ 44.4 $ (1,844.2 ) $ 1,571.0 Accounts payable and accrued expenses $ — $ — $ 12.5 — $ 56.9 $ 0.5 $ — $ 69.9 Deferred revenue — — — — 65.1 0.6 — 65.7 Intercompany payable — — — — 642.9 — (642.9 ) — Due to affiliates — — 5.6 — 1.7 — — 7.3 Capital lease obligations — — — — 6.2 7.2 — 13.4 Long-term debt — — 644.3 — — — — 644.3 Lease financing arrangements — — — — 20.9 32.5 — 53.4 Total liabilities — — 662.4 — 793.7 40.8 (642.9 ) 854.0 Total shareholders' equity 458.5 7.1 714.8 — 734.3 3.6 (1,457.5 ) 460.8 Noncontrolling interest — — — — — — 256.2 256.2 Total equity 458.5 7.1 714.8 — 734.3 3.6 (1,201.3 ) 717.0 Total liabilities and equity $ 458.5 $ 7.1 $ 1,377.2 $ — $ 1,528.0 $ 44.4 $ (1,844.2 ) $ 1,571.0 Consolidating Statements of Operations and Comprehensive Income (Loss) IN MILLIONS Year Ended December 31, 2015 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Revenue $ — $ — $ — $ — $ 393.8 $ 5.5 $ — $ 399.3 Costs and expenses: Property operating expenses — — — — 146.0 2.7 — 148.7 Sales and marketing — — — — 12.0 0.1 — 12.1 General and administrative — — — — 46.6 — — 46.6 Depreciation and amortization — — — — 138.7 2.8 — 141.5 Transaction and acquisition integration costs — — — — 14.1 — — 14.1 Asset impairments and loss on disposal — — — — 13.5 — — 13.5 Total costs and expenses — — — — 370.9 5.6 — 376.5 Operating income (loss) — — — — 22.9 (0.1 ) — 22.8 Interest expense — — 39.7 — — 3.2 (1.7 ) 41.2 Loss on extinguishment of debt — — — — — — — — (Loss) income before income taxes — — (39.7 ) — 22.9 (3.3 ) 1.7 (18.4 ) Income tax expense — — — — (1.8 ) — — (1.8 ) Equity (loss) earnings related to investment in subsidiaries (17.1 ) (0.2 ) 17.8 — (3.3 ) — 2.8 — Net (loss) income (17.1 ) (0.2 ) (21.9 ) — 17.8 (3.3 ) 4.5 (20.2 ) Noncontrolling interest in net loss — — — — — — 4.8 4.8 Net (loss) income attributed to common shareholders (17.1 ) (0.2 ) (21.9 ) — 17.8 (3.3 ) 9.3 (15.4 ) Other comprehensive loss — — — — — (0.2 ) — (0.2 ) Comprehensive loss attributable to common shareholders $ (17.1 ) $ (0.2 ) $ (21.9 ) $ — $ 17.8 $ (3.5 ) $ 9.3 $ (15.6 ) IN MILLIONS Year Ended December 31, 2014 Parent (1) General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Revenue $ — $ — $ — $ — $ 325.1 $ 5.8 $ — $ 330.9 Costs and expenses: Property operating expenses — — — — 121.9 2.6 — 124.5 Sales and marketing — — — — 12.6 0.2 — 12.8 General and administrative — — — — 34.2 0.4 — 34.6 Depreciation and amortization — — — — 115.0 3.0 — 118.0 Transaction and acquisition integration costs — — — — 1.0 — — 1.0 Total costs and expenses — — — — 284.7 6.2 — 290.9 Operating income (loss) — — — — 40.4 (0.4 ) — 40.0 Interest expense — — 38.2 — — 3.5 (2.2 ) 39.5 Loss on extinguishment of debt — — 13.6 — — — — 13.6 (Loss) income before income taxes — — (51.8 ) — 40.4 (3.9 ) 2.2 (13.1 ) Income tax expense — — — — (1.4 ) — — (1.4 ) Equity (loss) earnings related to investment in subsidiaries (10.0 ) (0.2 ) 35.1 — (3.9 ) — (21.0 ) — Net loss (10.0 ) (0.2 ) (16.7 ) — 35.1 (3.9 ) (18.8 ) (14.5 ) Noncontrolling interest in net loss — — — — — — 6.7 6.7 Net (loss) income attributed to common shareholders (10.0 ) (0.2 ) (16.7 ) — 35.1 (3.9 ) (12.1 ) (7.8 ) Other comprehensive loss — — — — — (0.3 ) — (0.3 ) Comprehensive loss attributable to noncontrolling interests — — — — — — 0.1 0.1 Comprehensive loss attributable to common shareholders $ (10.0 ) $ (0.2 ) $ (16.7 ) $ — $ 35.1 $ (4.2 ) $ (12.0 ) $ (8.0 ) IN MILLIONS Period Ended December 31, 2013 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Revenue $ — $ — $ — $ — $ 244.3 $ 4.1 $ — $ 248.4 Costs and expenses: Property operating expenses — — — — 85.9 2.5 — 88.4 Sales and marketing — — — — 9.7 0.2 — 9.9 General and administrative — — — — 26.3 0.2 — 26.5 Depreciation and amortization — — — — 87.1 2.8 — 89.9 Restructuring charges — — — — 0.7 — — 0.7 Transaction costs — — — — 1.3 — — 1.3 Asset impairment — — — — 2.8 — — 2.8 Total costs and expenses — — — — 213.8 5.7 — 219.5 Operating loss — — — — 30.5 (1.6 ) — 28.9 Interest expense — — 36.5 — 1.8 2.9 — 41.2 Other income — — — — (0.1 ) — — (0.1 ) Loss on extinguishment of debt — — — — 1.3 — — 1.3 Loss before income taxes — — (36.5 ) — 27.5 (4.5 ) — (13.5 ) Income tax expense — — — — (1.9 ) — — (1.9 ) Equity loss related to investment in subsidiaries (5.3 ) (0.2 ) 20.9 — (4.5 ) — (10.9 ) — Loss on sale of real estate improvements — — — — (0.2 ) — — (0.2 ) Net loss (5.3 ) (0.2 ) (15.6 ) — 20.9 (4.5 ) (10.9 ) (15.6 ) Noncontrolling interest in net loss — — — — — — (10.3 ) (10.3 ) Net income (loss) attributed to common shareholders $ (5.3 ) $ (0.2 ) $ (15.6 ) $ — $ 20.9 $ (4.5 ) $ (0.6 ) $ (5.3 ) IN MILLIONS Period Ended January 23, 2013 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Revenue $ — $ — $ — $ — $ 14.9 $ 0.2 $ — $ 15.1 Costs and expenses: Property operating expenses — — — — 4.8 — — 4.8 Sales and marketing — — — — 0.7 — — 0.7 General and administrative — — — — 1.4 0.1 — 1.5 Transaction-related compensation — — — — 20.0 — — 20.0 Depreciation and amortization — — — — 5.2 0.1 — 5.3 Transaction costs — — — — 0.1 — — 0.1 Total costs and expenses — — — — 32.2 0.2 — 32.4 Operating (loss) income — — — — (17.3 ) — — (17.3 ) Interest expense — — 2.3 — 0.1 0.1 — 2.5 Loss before income taxes — — (2.3 ) — (17.4 ) (0.1 ) — (19.8 ) Income tax expense — — — — (0.4 ) — — (0.4 ) Equity loss related to investment in subsidiaries — — (17.9 ) — (0.1 ) — 18.0 — Net loss $ — $ — $ (20.2 ) $ — $ (17.9 ) $ (0.1 ) $ 18.0 $ (20.2 ) Consolidating Statements of Cash Flows IN MILLIONS Year Ended December 31, 2015 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Net (loss) income $ (17.1 ) (0.2 ) $ (21.9 ) $ — 17.8 $ (3.3 ) $ 4.5 $ (20.2 ) Equity earnings (loss) related to investment in subsidiaries 17.1 0.2 (17.8 ) — 3.3 — (2.8 ) — Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities: Depreciation and amortization — — — — 138.7 2.8 — 141.5 Stock-based compensation expense — — — — 14.4 — — 14.4 Non-cash interest expense — — 3.4 — — — — 3.4 Provision for bad debt write off — — — — — — — — Loss on extinguishment of debt — — — — — — — — Asset impairments and loss on disposal — — — — 13.5 — — 13.5 Changes in operating assets and liabilities: Rent receivables and other assets — — — — (26.1 ) 2.2 — (23.9 ) Accounts payable and accrued expenses — — 16.7 — (9.8 ) 0.1 — 7.0 Deferred revenues — — — — 5.3 0.1 — 5.4 Due to affiliates — — — — (0.9 ) — — (0.9 ) Net cash (used in) provided by operating activities — — (19.6 ) — 156.2 1.9 1.7 140.2 Cash flows from investing activities: Capital expenditures - acquisitions of real estate — — — — (17.3 ) — — (17.3 ) Capital expenditures - other development — — — — (216.7 ) (0.5 ) — (217.2 ) Business acquisition, net of cash acquired — — — — (398.4 ) — — (398.4 ) Release of restricted cash — — — — 7.3 — — 7.3 Investment in and loans to subsidiaries (203.1 ) (2.0 ) (203.1 ) — (0.4 ) — 408.6 — Return of investment 62.6 — 102.0 — (17.9 ) — (146.7 ) — Intercompany contributions/distributions — — (348.4 ) — — — 348.4 — Net cash provided by (used in) investing activities (140.5 ) (2.0 ) (449.5 ) — (643.4 ) (0.5 ) 610.3 (625.6 ) Cash flows from financing activities: Issuance of common stock 799.5 — — — — — — 799.5 Stock issuance costs (0.8 ) — — — — — — (0.8 ) Acquisition of operating partnership units (596.4 ) — — — — — — (596.4 ) Dividends paid (61.0 ) — (80.8 ) — (80.8 ) — 141.8 (80.8 ) Intercompany borrowings — — — — 348.4 — (348.4 ) — Borrowings from credit facility — — 260.0 — — — — 260.0 Proceeds from issuance of debt — — 103.8 — — — — 103.8 Payments on credit facility — — (10.0 ) — — — — (10.0 ) Payments on senior notes — — — — — — — — Payments on capital leases and other financing arrangements — — — — (5.0 ) (0.9 ) — (5.9 ) Tax payment upon exercise of equity awards (0.8 ) — — — — — — (0.8 ) Contributions from/(distributions to) parent, net — 2.0 201.5 — 201.5 0.4 (405.4 ) — Debt issuance costs — — (5.4 ) — — — — (5.4 ) Net cash (used in) provided by financing activities 140.5 2.0 469.1 — 464.1 (0.5 ) (612.0 ) 463.2 Net (decrease) increase in cash and cash equivalents — — — — (23.1 ) 0.9 — (22.2 ) Cash and cash equivalents at beginning of period — — — — 33.5 3.0 — 36.5 Cash and cash equivalents at end of period $ — $ — $ — $ — $ 10.4 $ 3.9 $ — $ 14.3 IN MILLIONS Year Ended December 31, 2014 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Net (loss) income $ (10.0 ) (0.2 ) $ (16.7 ) $ — 35.1 $ (3.9 ) $ (18.8 ) $ (14.5 ) Equity earnings (loss) related to investment in subsidiaries 10.0 0.2 (35.1 ) — 3.9 — 21.0 — Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities: Depreciation and amortization — — — — 115.0 3.0 — 118.0 Stock-based compensation expense — — — — 10.3 — — 10.3 Non-cash interest expense — — 3.4 — — — — 3.4 Provision for bad debt write off — — — — 0.8 — — 0.8 Loss on extinguishment of debt — — 13.6 — — — — 13.6 Changes in operating assets and liabilities: Rent receivables and other assets — — 0.4 — (35.3 ) (2.1 ) — (37.0 ) Accounts payable and accrued expenses — — 4.7 — 2.1 0.1 — 6.9 Due to affiliates — — — — (0.2 ) — — (0.2 ) Deferred revenues — — — — 10.0 (0.2 ) — 9.8 Net cash provided by (used in) operating activities — — (29.7 ) — 141.7 (3.1 ) 2.2 111.1 Cash flows from investing activities: Capital expenditures - other development — — — — (283.9 ) (0.3 ) — (284.2 ) Return of investment 25.2 — 97.3 — (45.4 ) — (77.1 ) — Intercompany receipts — — 180.2 — — — (180.2 ) — Intercompany distributions — — (315.0 ) — — — 315.0 — Net cash (used in) provided by investing activities 25.2 — (37.5 ) — (329.3 ) (0.3 ) 57.7 (284.2 ) Cash flows from financing activities: Issuance of common stock 356.0 — — — — — — 356.0 Stock issuance costs (1.3 ) — — — — — — (1.3 ) Acquisition of operating partnership units (355.9 ) — — — — — — (355.9 ) Dividends paid (24.0 ) — (50.9 ) — (50.9 ) — 74.9 (50.9 ) Intercompany borrowings — — — — 315.0 — (315.0 ) — Intercompany payments — — — — (180.2 ) — 180.2 — Borrowings from credit facility — — 315.0 — — — — 315.0 Payments on credit facility — — (30.0 ) — — — — (30.0 ) Payments on senior notes — — (150.2 ) — — — — (150.2 ) Payments on capital leases obligations — — — — (2.4 ) (0.6 ) — (3.0 ) Payments on financing arrangements — — — — (0.7 ) (0.2 ) — (0.9 ) Payment of debt extinguishment costs — — (12.8 ) — — — — (12.8 ) Contributions from/(distributions to) parent, net — — 1.3 — (6.5 ) 5.2 — — Debt issuance costs — — (5.2 ) — — — — (5.2 ) Net cash provided by (used in) financing activities (25.2 ) — 67.2 — 74.3 4.4 (59.9 ) 60.8 Net (decrease) increase in cash and cash equivalents — — — — (113.3 ) 1.0 — (112.3 ) Cash and cash equivalents at beginning of period — — — — 146.8 2.0 — 148.8 Cash and cash equivalents at end of period $ — $ — $ — $ — $ 33.5 $ 3.0 $ — $ 36.5 IN MILLIONS Period Ended December 31, 2013 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Net (loss) income $ (5.3 ) $ (0.2 ) $ (15.6 ) $ — $ 20.9 $ (4.5 ) $ (10.9 ) $ (15.6 ) Equity loss related to investment in subsidiaries 5.3 0.2 (20.9 ) — 4.5 — 10.9 — Adjustments to reconcile net (loss) income to net cash provided by operating activities: Depreciation and amortization — — — — 87.1 2.8 — 89.9 Stock-based compensation expense — — — — 6.0 — — 6.0 Non-cash interest expense — — 4.0 — — — — 4.0 Provision for bad debt write off — — — — 0.4 — — 0.4 Loss on extinguishment of debt — — — — 1.3 — — 1.3 Asset impairments and loss on disposal — — — — 2.8 — — 2.8 Deferred income tax expense, including valuation allowance change — — — — 0.6 — — 0.6 Other, net (7.1 ) — (13.4 ) — (16.2 ) — 36.7 — Changes in operating assets and liabilities: Rent receivables and other assets 9.4 — — — (9.9 ) (3.0 ) (12.2 ) (15.7 ) Accounts payable and accrued expenses (2.3 ) — 4.8 — 0.2 0.3 (17.6 ) (14.6 ) Due to affiliates — — 6.8 — 18.4 — (6.8 ) 18.4 Deferred revenues — — — — (0.3 ) 0.2 — (0.1 ) Net cash provided by operating activities — — (34.3 ) — 115.8 (4.2 ) 0.1 77.4 Cash flows from investing activities: Capital expenditures - acquisitions of real estate — — — — (48.0 ) — — (48.0 ) Capital expenditures - other development — — — — (172.9 ) — — (172.9 ) Investment in subsidiaries (337.1 ) — (337.1 ) — — — 674.2 — Release of restricted cash — — — — 4.4 — — 4.4 Return of investment 10.6 — 66.5 — — — (77.1 ) — Other — — — — (0.2 ) — — (0.2 ) Net cash provided by (used in) investing activities (326.5 ) — (270.6 ) — (216.7 ) — 597.1 (216.7 ) Cash flows from financing activities: Issuance of common stock/partnership units 360.5 — 337.1 — — — (337.1 ) 360.5 IPO costs (23.4 ) — — — (3.2 ) — — (26.6 ) Dividends paid (10.6 ) — (31.0 ) — (31.0 ) — 41.6 (31.0 ) Payments on capital leases — — — — (4.4 ) (0.9 ) — (5.3 ) Payments on financing obligations — — — — (0.5 ) (0.2 ) — (0.7 ) Payment to buyout capital leases — — — — (9.6 ) — — (9.6 ) Payment to buyout other financing arrangements — — — — (10.2 ) — — (10.2 ) Contributions from parent guarantor — — — — 295.4 6.3 (301.7 ) — Debt issuance costs — — (1.3 ) — — — — (1.3 ) Net cash provided by (used in) financing activities 326.5 — 304.8 — 236.5 5.2 (597.2 ) 275.8 Net increase (decrease) in cash and cash equivalents — — (0.1 ) — 135.6 1.0 — 136.5 Cash and cash equivalents at beginning of period — — 0.1 — 11.2 1.0 — 12.3 Cash and cash equivalents at end of period $ — $ — $ — $ — $ 146.8 $ 2.0 $ — $ 148.8 IN MILLIONS Period Ended January 23, 2013 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Net (loss) income $ — $ — $ (20.2 ) $ — $ (17.9 ) $ (0.1 ) $ 18.0 $ (20.2 ) Equity loss related to investment in subsidiaries — — 17.9 — 0.1 — (18.0 ) — Adjustments to reconcile net (loss) income to net cash provided by operating activities — — 0.2 — 5.6 0.1 — 5.9 Changes in operating assets and liabilities: Rent receivables and other assets — — — — (9.6 ) — — (9.6 ) Accounts payable and accrued expenses — — 2.1 — 18.4 — — 20.5 Due to affiliates — — — — 1.5 — — 1.5 Other changes in assets and liabilities — — — — 3.8 0.1 — 3.9 Net cash provided by operating activities — — — — 1.9 0.1 — 2.0 Cash flows from investing activities: Capital expenditures - other development — — — — (7.7 ) — — (7.7 ) Release of restricted cash — — — — 1.9 — — 1.9 Intercompany advances, net — — 0.1 — (0.1 ) — — — Net cash provided by (used in) investing activities — — 0.1 — (5.9 ) — — (5.8 ) Cash flows from financing activities: Payments on capital lease obligations — — — — (0.6 ) — — (0.6 ) Contributions from/(distributions to) parent, net — — — — 0.2 — — 0.2 Net cash used in financing activities — — — — (0.4 ) — — (0.4 ) Net increase (decrease) in cash and cash equivalents — — 0.1 — (4.4 ) 0.1 — (4.2 ) Cash and cash equivalents at beginning of period — — — — 15.6 0.9 — 16.5 Cash and cash equivalents at end of period $ — $ — $ 0.1 $ — $ 11.2 $ 1.0 $ — $ 12.3

Quarterly Financial Information

Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2015
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, 2015 and 2014 : IN MILLIONS, except per share amounts 2015 First Quarter Second Quarter Third Quarter Fourth Total Revenue $ 85.7 $ 89.1 $ 111.2 $ 113.3 $ 399.3 Operating income 1.6 2.6 7.5 11.1 22.8 Net income (loss) (7.2 ) (6.5 ) (5.3 ) (1.2 ) (20.2 ) Net income (loss) attributed to common shareholders (4.3 ) (5.5 ) (4.6 ) (1.0 ) (15.4 ) Basic and diluted loss per share (a) $ (0.12 ) $ (0.11 ) $ (0.08 ) $ (0.02 ) $ (0.33 ) IN MILLIONS, except per share amounts 2014 First Second Quarter Third Quarter Fourth Quarter Total Revenue $ 77.5 $ 81.7 $ 84.8 $ 86.9 $ 330.9 Operating (loss) income 11.8 7.4 9.6 11.2 40.0 Net loss 0.7 (3.6 ) 0.2 (11.8 ) (14.5 ) Net loss attributed to common shareholders 0.2 (1.1 ) 0.1 (7.0 ) (7.8 ) Basic and diluted loss per share (b) $ — $ (0.06 ) $ — $ (0.19 ) $ (0.25 ) (a) The basic and diluted income (loss) per share for 2015 was $(0.30) compared to $(0.33) due to the impact of the 14.3 million shares of common stock issued during the secondary offering in April 2015, and the 6.0 million shares of common stock issued during the secondary offering in June 2015. (b) The basic and diluted income (loss) per share for 2014 was $(0.30) compared to $(0.25) due to the impact of the 16.0 million shares of common stock issued during the secondary offering in June 2014.

Subsequent Event

Subsequent Event	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Event	Subsequent Event None.

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2015
Valuation and Qualifying Accounts [Abstract]
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 2015 $ 1.0 $ — $ — $ 1.0 2014 0.5 0.8 0.3 1.0 2013 0.3 0.4 0.2 0.5 Deferred Tax Valuation Allowance 2015 $ 5.7 $ 0.6 $ — $ 6.3 2014 3.6 2.1 — 5.7 2013 1.9 1.7 — 3.6

Real Estate Properties and Accu

Real Estate Properties and Accumulated Depreciation	12 Months Ended
	Dec. 31, 2015
SEC Schedule III, Real Estate and Accumulated Depreciation Disclosure [Abstract]
Real Estate and Accumulated Depreciation Disclosure	Real Estate Properties and Accumulated Depreciation CyrusOne Inc. As of December 31, 2015 (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 West Seventh St., Cincinnati, OH (7th Street) $ 0.9 $ 42.2 $ — $ — $ 68.4 $ 19.6 $ 0.9 $ 110.6 $ 19.6 $ 75.1 1999 Parkway Dr., Mason, OH (Mason) — — — — 20.2 1.0 — 20.2 1.0 11.8 2004 Industrial Rd., Florence, KY (Florence) 2.2 7.7 — — 33.8 3.3 2.2 41.5 3.3 21.8 2005 Goldcoast Dr., Cincinnati, OH (Goldcoast) 0.6 — — — 6.7 0.1 0.6 6.7 0.1 2.6 2007 Knightsbridge Dr., Hamilton, OH (Hamilton) — 9.5 — — 39.7 4.4 — 49.2 4.4 22.7 2007 E. Monroe St., South Bend, IN (Monroe St.) — — — — 2.5 0.3 — 2.5 0.3 1.3 2007 Springer St., Lombard, IL (Lombard) 0.7 3.2 — — 1.5 7.6 0.7 4.7 7.6 2.9 2008 Crescent Circle, South Bend, IN (Blackthorn) — 1.1 — — 2.2 0.4 — 3.3 0.4 1.5 2008 Kingsview Dr., Lebanon, OH (Lebanon) 4.0 12.3 — — 65.0 7.6 4.0 77.3 7.6 26.5 2008 McAuley Place, Blue Ash, OH (Blue Ash) — 2.6 — — (2.0 ) 0.1 — 0.6 0.1 0.3 2009 Westway Park Blvd., Houston, TX (Houston West 1) 1.4 21.4 0.1 — 63.4 46.3 1.4 84.8 46.4 51.7 2010 Westway Park Blvd., Houston, TX (Houston West 2) 2.0 — — — 22.6 47.1 2.0 22.6 47.1 15.3 2013 Westway Park Blvd., Houston, TX (Houston West 3) 18.3 — — 0.1 4.0 0.8 18.4 4.0 0.8 0.3 2013 Southwest Fwy., Houston, TX (Galleria) — 56.0 2.0 — 12.6 14.0 — 68.6 16.0 36.8 2010 E. Ben White Blvd., Austin, TX (Austin 1) — 11.9 0.2 — 1.7 0.8 — 13.6 1.0 10.1 2010 S. State Highway 121 Business, Lewisville, TX (Lewisville) — 46.2 2.2 — 30.4 22.7 — 76.6 24.9 45.3 2010 Marsh Lane, Carrollton, TX (Marsh Ln) — — — — 0.1 0.6 — 0.1 0.6 0.4 2010 Midway Rd., Carrollton, TX (Midway) — 1.8 — — 0.2 0.4 — 2.0 0.4 2.2 2010 W. Frankford Rd., Carrollton, TX (Carrollton) 16.1 — — — 52.7 116.5 16.1 52.7 116.5 34.3 2012 Bryan St., Dallas, TX (Bryan St) — 0.1 — — (0.1 ) — — — — — 2010 North Freeway, Houston, TX (Greenspoint) — — — — — — — — — — 2010 South Ellis Street, Chandler, AZ (Phoenix 1) 14.8 — — — 56.7 39.8 14.8 56.7 39.8 18.5 2011 South Ellis Street, Chandler, AZ (Phoenix 2) — — — — 16.0 39.5 — 16.0 39.5 5.3 2014 Westover Hills Blvd., San Antonio, TX (San Antonio 1) 4.6 3.0 — — 29.1 33.0 4.6 32.1 33.0 15.9 2011 Westover Hills Blvd., San Antonio, TX (San Antonio 2) 6.7 — — 0.3 — 0.1 7.0 — 0.1 — 2013 Metropolis Dr., Austin, TX (Austin 2) 2.0 — — — 23.2 5.7 2.0 23.2 5.7 9.6 2011 Myer Conners Rd (Wappinger Falls) — 9.9 13.3 — 1.4 1.1 — 11.3 14.4 1.3 2015 Madison Road (Totowa) — 28.3 45.6 — — 3.2 — 28.3 48.8 3.8 2015 Commerce Road (Totowa) — 4.1 0.8 — — 0.2 — 4.1 1.0 0.2 2015 Norden Place (Norwalk) — 18.3 25.3 — — 0.1 — 18.3 25.4 1.6 2015 Riverbend Drive South (Stamford) — 4.3 13.2 — — — — 4.3 13.2 1.2 2015 Omega Drive (Stamford) — 3.2 0.6 — — 0.9 — 3.2 1.5 0.2 2015 Kestral Way (London) — 16.5 — — 14.7 0.8 — 31.2 0.8 6.0 2011 Jurong East (Singapore) — 9.0 — — (0.6 ) 0.1 — 8.4 0.1 3.6 2011 Ridgetop Circle, Sterling, VA (Northern Virginia) 6.9 — — 0.1 19.2 45.2 7.0 19.2 45.2 5.0 2013 Metropolis Dr., Austin, TX (Austin 3) 7.9 — — 0.1 — 0.1 8.0 — 0.1 — 2013 Metropolis Dr., Austin, TX (Austin 4) 3.3 $ — $ — — 7.4 31.5 3.3 7.4 31.5 0.5 2015 $ 92.4 $ 312.6 $ 103.3 $ 0.6 $ 592.7 $ 494.9 $ 93.0 $ 905.3 $ 598.2 $ 435.6 The aggregate cost of the total properties for federal income tax purposes was $2,419.1 million at December 31, 2015 . Historical Cost and Accumulated Depreciation and Amortization The following table reconciles the historical cost and accumulated depreciation for the years ended December 31, 2015 , 2014 and 2013 . Years Ended December 31, (amounts in millions) 2015 2014 2013 Property Balance—beginning of period $ 1,378.4 $ 1,120.5 $ 883.6 Disposals (7.0 ) (0.1 ) (8.5 ) Impairments (9.3 ) — (4.0 ) Additions (acquisitions and improvements) 465.5 258.0 249.4 Balance, end of period $ 1,827.6 $ 1,378.4 $ 1,120.5 Accumulated Depreciation Balance—beginning of period $ 327.0 $ 236.7 $ 176.7 Disposals (2.7 ) — (9.3 ) Impairments — — (0.9 ) Additions (depreciation and amortization expense) 111.3 90.3 70.2 Balance, end of period $ 435.6 $ 327.0 $ 236.7

Significant Accounting Polici34

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying financial statements for the period ended January 23, 2013 were prepared on a combined basis using CBI’s historical basis in the assets and liabilities of its data center business and are presented as the “Predecessor” financial statements. The Predecessor financial statements include all revenues, costs, assets and liabilities directly attributable to the data center business. In addition, certain expenses reflected in the Predecessor financial statements include allocations of corporate expenses from CBI, which in the opinion of management are reasonable but do not necessarily reflect what CyrusOne’s financial position, results of operations and cash flows would have been had CyrusOne been a stand-alone company during this period. The financial statements as of December 31, 2015 and 2014 and for the period from January 24, 2013 to December 31, 2013, and the years ended December 31, 2015 and December 31, 2014, are prepared on a consolidated basis and are presented as the “Successor” financial statements. In addition, the accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (GAAP). All material intercompany transactions and balances have been eliminated in consolidation. All prior year amounts have been presented to conform to current year's presentation.
Use of Estimates	Use of Estimates —Preparation of the consolidated and combined financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated and combined financial statements and accompanying notes. These estimates and assumptions are based on management’s knowledge of current events and actions that we may undertake in the future. Estimates are used in determining the fair value of leased real estate, the useful lives of real estate and other long-lived assets, future cash flows associated with goodwill and other long-lived asset impairment testing, deferred tax assets and liabilities and loss contingencies. Estimates were also utilized in the determination of historical allocations of shared employees’ payroll, benefits and incentives and management fees between CyrusOne and CBI. Actual results may differ from these estimates and assumptions.
Investments in Real Estate	Investment in Real Estate —Investment in real estate consist of land, buildings, improvements and integral equipment utilized in our data center operations. Real estate acquired from third parties has been recorded at its acquisition cost. Real estate acquired from CBI and its affiliates has been recorded at its historical cost basis. Additions and improvements which extend an asset’s useful life or increase its functionality are capitalized and depreciated over the asset’s remaining life. Maintenance and repairs are expensed as incurred. When we are involved in the construction of structural improvements to leased property, we are deemed the accounting owner of the leased real estate. In these instances, we bear substantially all the construction period risk, including managing or funding construction. As we have substantially all of the construction risks, we are deemed the “owner” of the asset under construction for accounting purposes during the construction period, and are therefore required to capitalize the construction costs on the accompanying consolidated balance sheets. At inception, the fair value of the building (excluding land) is recorded as an asset and the construction and modification costs to the building, that are not funded by us would be recorded as a liability. As construction progresses, the value of the asset and obligation increases by the fair value of the structural improvements. At completion of the construction, Sales-Leaseback Accounting under ASC 840-40-25 is also evaluated. Due to our continuing involvement with the lessor, Sales-Leaseback Accounting is precluded and the liability is not derecognized. When the asset is placed in service, depreciation commences, and the leased real estate is depreciated to the lesser of (i) its estimated fair value at the end of the term or (ii) the expected amount of the unamortized obligation at the end of the term. The associated obligation is presented as lease financing arrangements in the accompanying consolidated balance sheets. When we are not deemed the accounting owner of leased real estate, we further evaluate the lease to determine whether the lease should be classified as a capital or operating lease. One of the following four characteristics must be present to classify a lease as a capital lease: (i) the lease transfers ownership of the property to the lessee by the end of the lease term, (ii) the lease contains a bargain purchase option, (iii) the lease term is equal to 75% or more of the estimated economic life of the leased property or (iv) the net present value of the lease payments are at least 90% of the fair value of the leased property. Construction in progress includes direct and indirect expenditures for the construction and expansion of our data centers and is stated at its acquisition cost. Independent contractors perform substantially all of the construction and expansion efforts of our data centers. Construction in progress includes costs incurred under construction contracts including project management services, engineering and schematic design services, design development, construction services and other construction-related fees and services. Interest, property taxes and certain labor costs are also capitalized during the construction of an asset. Capitalized interest in 2015 , 2014 , and 2013 was $6.1 million , $4.6 million , and $1.6 million , respectively. These costs are depreciated over the estimated useful life of the related assets. Depreciation is calculated using the straight-line method over the estimated useful life of the asset. Useful lives range from nine to thirty years for buildings, three to thirty years for building improvements, and three to twenty years for equipment. Leasehold improvements are amortized over the shorter of the asset’s useful life or the remaining lease term, including renewal options which are reasonably assured. Management reviews the carrying value of long-lived assets, including intangible assets with finite lives, when events or changes in circumstances indicate that the carrying amount of the assets may not be recoverable. Examples of such indicators may include a significant adverse change in the extent to which or manner in which the property is being used, an accumulation of costs significantly in excess of the amount originally expected for acquisition or development, or a history of operating or cash flow losses. When such indicators exist, we review an estimate of the undiscounted future cash flows expected to result from the use of an asset (or group of assets) and its eventual disposition and compare such amount to its carrying amount. We consider factors such as future operating income, leasing demand, competition and other factors. If our undiscounted net cash flows indicate that we are unable to recover the carrying value of the asset, an impairment loss is recognized. An impairment loss is measured as the amount by which the asset’s carrying value exceeds its estimated fair value.
Cash and Cash Equivalents	Cash and Cash Equivalents —Cash and cash equivalents include all non-restricted cash held in financial institutions and other non-restricted highly liquid short-term investments with original maturities at acquisition of three months or less.
Restricted Cash	Restricted Cash —Restricted cash includes cash equivalents held to collateralize standby letters of credit and/or deposited in escrow to fund construction or pending potential acquisition transactions. In addition, we may have other cash that is not immediately available for use in current operations.
Goodwill	Goodwill —Goodwill represents the excess of the purchase price over the fair value of net assets acquired in connection with business acquisitions. We perform impairment testing of goodwill, at the reporting unit level, on an annual basis or more frequently if indicators of potential impairment exist. The fair value of our reporting unit was determined using a combination of market-based valuation multiples for comparable businesses and discounted cash flow analysis based on internal financial forecasts incorporating market participant assumptions.
Long-Lived and Intangible Assets	Long-Lived and Intangible Assets —Intangible assets represent purchased assets that lack physical substance, but can be separately distinguished from Goodwill because of contractual or other legal rights or because the asset is capable of being sold or exchanged, either on its own or in combination with a related contract, asset, or liability. Intangible assets with finite lives consist of trademarks, customer relationships, and a favorable leasehold interest.
Receivables	Rent and Other Receivables —Receivables consist principally of trade receivables from customers and are generally unsecured and due within 30 to 120 days . Unbilled receivables arise from services rendered but not yet billed. Expected credit losses associated with trade receivables are recorded as an allowance for uncollectible accounts. The allowance for uncollectible accounts is estimated based upon historic patterns of credit losses for aged receivables as well as specific provisions for certain identifiable, potentially uncollectible balances. When internal collection efforts on receivables have been exhausted, the receivables are written-off and the associated allowance for uncollectible accounts is reduced.
Deferred Costs	Deferred Leasing Costs —Deferred leasing costs are presented with Other assets in the accompanying consolidated balance sheets. Leasing commissions incurred at the commencement of a new lease are capitalized and amortized over the term of the customer lease. Amortization of deferred leasing costs is presented with Depreciation and amortization in the accompanying consolidated and combined statements of operations. If a lease terminates prior to the expiration of the lease, the remaining unamortized cost is written off to amortization expense. As of December 31, 2015 and 2014, deferred leasing costs were $14.2 million and $12.8 million , respectively. Deferred Financing Costs —Deferred financing costs include costs incurred in connection with issuance of debt, including 6.375% senior notes, term loans and revolving credit facilities. These financing costs are capitalized and amortized to expense over the term of the instrument and are included as a component of Interest expense. These costs include deferred financing costs associated with our revolving line of credit and are presented in the balance sheet as a direct reduction from the carrying amount of the debt liability to conform to the 2015 presentation.
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 —Colocation rentals are generally billed monthly in advance, and some contracts have escalating payments over the term of the contract. If rents escalate without the lessee gaining access to or control over additional leased space or power, and the lessee takes possession of, or controls the physical use of the property (including all contractually committed power) at the beginning of the lease term, the rental payments by the lessee are recognized as revenue on a straight-line basis over the term of the lease. If rents escalate because the lessee gains access to and control over additional leased space or power, revenue is recognized in proportion to the additional space or power in the periods that the lessee has control over the use of the additional space or power. The excess of revenue recognized over amounts contractually due is recognized in Other assets in the accompanying consolidated balance sheets. As of December 31, 2015 and 2014, straight-line rent receivable was $44.7 million and $33.7 million , respectively. Some of our leases are structured on a full-service gross basis in which the customer pays a fixed amount for both colocation rent and power. Other leases provide that the customer will be billed for power based upon actual usage times a load factor. Power is generally billed one month in arrears and an estimate of this revenue is accrued in the month that the associated costs are incurred. We generally are not entitled to reimbursements for real estate taxes, insurance or other operating expenses. Revenue is recognized for services or products that are deemed separate units of accounting. When a customer makes an advance payment or they are contractually obligated to pay any amounts in advance, which is not deemed a separate unit of accounting, Deferred revenue is recorded. This revenue is recognized ratably over the expected term of the lease, unless the pattern of service suggests otherwise. As of December 31, 2015 and 2014 , Deferred revenue was $78.7 million and $65.7 million , respectively. Certain customer leases require specified levels of service or performance. If we fail to meet these service levels, our customers may be eligible to receive credits on their contractual billings. These credits are recognized against revenue when an event occurs that gives rise to such credits. Customer credits were immaterial for each of the years presented. A provision for uncollectible accounts is recognized when the collection of contractual rent, straight-line rent or customer reimbursements are deemed to be uncollectible.
Sales and Marketing Expense	Sales and Marketing Expense —Sales and marketing expense is comprised of compensation and benefits associated with Sales and marketing personnel as well as advertising and marketing costs. Costs related to advertising are expensed as incurred and amounted to $2.2 million for the year ended December 31, 2015, $2.9 million for the year ended December 31, 2014, $2.1 million for the period ended December 31, 2013, and $0.1 million for the period ended January 23, 2013.
Depreciation and Amortization Expense	Depreciation and Amortization Expense —Depreciation expense is recognized over the estimated useful lives of real estate applying the straight-line method. The useful life of leased real estate and leasehold improvements is the lesser of the economic useful life of the asset or the term of the lease, including optional renewal periods if renewal of the lease is reasonably assured. The residual value of leased real estate is estimated as the lesser of (i) the expected fair value of the asset at the end of the lease term or (ii) the expected amount of the unamortized liability at the end of the lease term. Estimated useful lives are periodically reviewed. Depreciation expense was $117.8 million for the year ended December 31, 2015, $95.8 million for the year ended December 31, 2014, $70.3 million for the period ended December 31, 2013, and $4.1 million for the period ended January 23, 2013. Amortization expense is recognized over the estimated useful lives of finite-lived intangibles. Finite-lived intangibles include trademarks, favorable leasehold interests, deferred leasing costs and deferred sales commissions. As of December 31, 2015, the estimated weighted average useful life of trademarks and customer relationships was ten and 13 years, respectively. In addition, we have a favorable leasehold interest related to a land lease that is being amortized over the lease term of fifty-one years.
Transaction Costs	Transaction and Acquisition Integration Costs —Transaction costs represent incremental legal, accounting and professional fees incurred in connection with our formation transactions, our initial qualification as a real estate investment trust, or REIT, and business combination and asset acquisition costs (including unsuccessful efforts). Transaction costs are expensed as incurred and do not include any recurring costs from our ongoing operations. Integration costs represent incremental costs to integrate a consummated acquisition.
Transaction-related Compensation	Transaction-Related Compensation —During the period ended January 23, 2013, the Company received an allocated compensation charge from CBI of $20.0 million for the settlement of its long-term incentive plan associated with the completion of the IPO. The amount was determined by CBI and allocated to CyrusOne Inc. on January 23, 2013, and reflected as expense and contributed capital in the respective period.
Income Taxes	Income Taxes —CyrusOne Inc. was included in CBI’s consolidated tax returns in various jurisdictions for the Predecessor period and was included in the Successor period for Texas only until June 26, 2014 when CBI's ownership percentage in the operating partnership was reduced below 50%. In the accompanying financial statements, the Predecessor period and the Successor period (for Texas only until June 26, 2014) reflect income taxes as if the Company were a separate stand-alone company. The income tax provision consists of an amount for taxes currently payable and an amount for tax consequences deferred to future periods. CyrusOne Inc. elected to be taxed as a REIT under the Internal Revenue Code of 1986, as amended (Code), commencing with our initial taxable year ending December 31, 2013. Provided we continue to meet the various qualification tests mandated under the Code, we are generally not subject to corporate level federal income tax on the earnings distributed currently to our shareholders. If we fail to qualify as a REIT in any taxable year, our taxable income will be subject to federal income tax at regular corporate rates and any applicable alternative minimum tax. While CyrusOne Inc. and the operating partnership do not pay federal income taxes, we are still subject to foreign, state and local income taxes in the locations in which we conduct business. Our taxable REIT subsidiaries (each a TRS) are also subject to federal and state income taxes to the extent they earn taxable income. Deferred income taxes are recognized in certain entities. Deferred income taxes are provided for temporary differences in the bases between financial statement and income tax assets and liabilities. Deferred income taxes are recalculated annually at rates then in effect. Valuation allowances are recorded to reduce deferred tax assets to amounts that are more likely than not to be realized. The ultimate realization of the deferred tax assets depends upon our ability to generate future taxable income during the periods in which basis differences and other deductions become deductible and prior to the expiration of the net operating loss carryforwards. The Company and its subsidiaries file income tax returns in the U.S. federal jurisdiction as well as various state, local and foreign jurisdictions. The Company's previous tax filings are subject to normal reviews by regulatory agencies until the related statute of limitations expires. With a few exceptions, the Company is no longer subject to U. S. federal, state or local examinations for years prior to 2012, and we have no liabilities for uncertain tax positions as of December 31, 2015 or 2014.
Foreign Currency Translation and Transactions	Foreign Currency Translation and Transactions —The financial position of foreign subsidiaries is translated at the exchange rates in effect at the end of the period, while revenues and expenses are translated at average rates of exchange during the period. Gains or losses from translation of foreign operations where the local currency is the functional currency are included as components of other comprehensive (loss) income. Gains or losses from foreign currency transactions are included in determining net income.
Comprehensive Loss	Comprehensive Loss —Comprehensive loss represents the change in net assets of a company from transactions and other events from non-owner sources. Comprehensive loss comprises all components of net loss and all components of other comprehensive loss. Subsequent to the issuance of the Company’s 2014 consolidated financial statements, the Company identified an error in the Consolidated Statements of Comprehensive Income (Loss) and the Consolidated Balance Sheets and Statements of Equity. The Consolidated Statements of Comprehensive Income (Loss) excluded allocations of net loss attributable to noncontrolling interests and only attributed foreign currency translation adjustment allocations to the noncontrolling interest. This error resulted in the understatement of “Comprehensive Loss Attributable to Non-Controlling Interests” of ($6.7) million for the year ended December 31, 2014 (Successor), and ($10.3) million for the Successor period ended December 31, 2013, as well as the corresponding understatement of the total “Comprehensive Loss Attributable to CyrusOne Inc.”. The Consolidated Statements of Equity did not present the comprehensive loss attributed to foreign currency translation adjustment allocations to noncontrolling interest. This error resulted in “Foreign Currency Translation Adjustment” allocated to CyrusOne Inc. to be overstated and the amount allocated to Noncontrolling Interest to be understated by $0.1 million for the year ended December 31, 2014 (Successor) and “Accumulated Other Comprehensive Loss” and “Noncontrolling Interest” to be overstated by $0.1 million
Earnings Per Share	Earnings Per Share —For all periods subsequent to January 23, 2013, we present earnings per share (EPS) data. Basic EPS includes only the weighted average number of common shares outstanding during the period. Diluted EPS includes the weighted average number of common shares and the dilutive effect of stock options, restricted stock and share unit awards outstanding during the period, when such instruments are dilutive. All outstanding unvested share-based payment awards that contain rights to nonforfeitable dividends are treated as participating in undistributed earnings with common shareholders. Awards of this nature are considered participating securities and the two-class method of computing basic and diluted EPS must be applied.
Related Party Transactions	Related Party Transactions —CBI provided us with a variety of services. Cost allocation methods which were employed to determine the costs to be recognized in the accompanying combined financial statements included the following: • Specific identification—Applied when amounts were specifically identifiable to our operations. • Reasonable allocation method—When amounts were not clearly or specifically identifiable to our operations, management applied a reasonable allocation method.
Stock-Based Compensation	Stock-Based Compensation —In conjunction with the IPO, our board of directors adopted the 2012 Long-Term Incentive Plan (LTIP). The LTIP is administered by the compensation committee of the board of directors, or the plan administrator. Awards issuable under the LTIP include common stock, restricted stock, stock options and other incentive awards. See Note 16 to our audited consolidated and combined financial statements included elsewhere in this Annual Report on Form 10-K for additional details relating to these awards. Share-based compensation expense is based on the estimated grant-date fair value. CyrusOne Inc. recognizes share-based compensation expense, less estimated forfeitures, on a straight-line basis over the requisite service period for time-based awards and on a graded vesting basis for performance-based awards. CyrusOne estimates forfeitures based on historical activity, expected employee turnover, and other qualitative factors which are adjusted for changes in estimates and award vesting. All expenses for an award will be recognized by the time it becomes fully vested. CyrusOne Inc. uses the Black-Scholes-Merton option pricing model to calculate the fair value of stock options. This option valuation model requires the use of subjective assumptions, including the estimated fair value of the underlying common stock, the expected stock price volatility, and the expected term of the option. The estimated fair value of the underlying common stock is based on third-party valuations. Our volatility estimates are based on a peer group of companies. We estimate the expected term of the awards to be the weighted average mid-point between the vesting date and the end of the contractual term. We use this method to estimate the expected term since we do not have sufficient historical exercise data. For interim periods, we use our year-to-date actual results, financial forecasts, and other available information to estimate the probability of the award vesting based on the performance metrics.
Fair Value Measurements	Fair Value Measurements —Fair value measurements are utilized in accounting for business combinations and testing of goodwill and other long-lived assets for impairment and disclosures. Fair value of financial and non-financial assets and liabilities is defined as an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. The three-tier hierarchy for inputs used in measuring fair value, which prioritizes the inputs used in the methodologies of measuring fair value for asset and liabilities, is as follows: Level 1—Observable inputs for identical instruments such as quoted market prices; Level 2—Inputs include quoted prices for similar assets and liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (i.e., interest rates, yield curves, etc.), and inputs that are derived principally from or corroborated by observable market data by correlation or other means (market corroborated inputs); and Level 3—Unobservable inputs that reflect our determination of assumptions that market participants would use in pricing the asset or liability. These inputs are developed based on the best information available, including our own data.
Business Segments	Business Segments —Business segments are components of an enterprise for which separate financial information is available and regularly viewed by the chief operating decision maker to assess performance and allocate resources. Our chief operating decision maker, the Company's Chief Executive Officer, reviews our financial information on an aggregate basis. Furthermore, our data centers have similar economic characteristics and customers across all geographic locations, our service offerings have similar production processes, deliver services in a similar manner and use the same types of facilities and similar technologies. As a result, we have concluded that we have one reportable operating segment.
Recently Issued Accounting Standards	Accounting Standards Update (ASU) No. 2014-09 (ASU 2014-09), Revenue from Contracts with Customers (Topic 606) In May 2014, the Financial Accounting Standards Board (FASB) issued guidance that outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes most of the existing revenue recognition guidance. This guidance requires an entity to recognize revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services and also requires certain additional disclosures which are effective for interim and annual reporting periods in fiscal years that begin after December 15, 2016. In July 2015, the FASB voted to approve a one-year deferral of the effective date to December 15, 2017 for interim and annual reporting periods beginning after that date and permitted early adoption of the standard, but not before the original effective date of December 15, 2016. This guidance permits two implementation approaches. Companies can chose to apply the standard retrospectively to each prior reporting period presented (full retrospective application) or retrospectively with the cumulative effect of initially applying the standard as an adjustment to the opening balance of retained earnings of the annual reporting period that includes the date of initial application (modified retrospective application). We are currently evaluating the impact of the adoption of this guidance in our consolidated financial statements. ASU No. 2014-12 (ASU 2014-12), Compensation-Stock Compensation (Topic 718): Accounting for Share-Based Payments When the Terms of an Award Provide That a Performance Target Could Be Achieved After the Requisite Service Period In June 2014, the FASB issued a guidance update for the presentation of stock compensation. This guidance requires an entity to treat performance targets that can be met after the requisite service period of a share based award has ended, as a performance condition that affects vesting and is effective for interim and annual reporting periods in fiscal years that begin after December 15, 2015. Since the Company's share-based awards do not contain performance targets that could be achieved after the employee completes the requisite service, the adoption of this guidance has no impact on our consolidated financial statements. ASU No. 2014-15 (ASU 2014-15), Presentation of Financial Statements - Going Concern (Subtopic 205-40) In August 2014, the FASB issued guidance on determining when and how reporting entities must disclose going-concern uncertainties in their financial statements. The new standard requires management to perform interim and annual assessments of an entity’s ability to continue as a going concern within one year of the date of issuance of the entity’s financial statements. This guidance is effective for annual periods ending after December 15, 2016, and interim periods thereafter; early adoption is permitted. We are currently evaluating the full impact of the new standard. ASU No. 2015-01 (ASU 2015-01), Extraordinary and Unusual Items (Subtopic 225-20): Simplifying Income Statement Presentation by Eliminating the Concept of Extraordinary Items In January 2015, the FASB issued guidance eliminating from U.S. GAAP the concept of an extraordinary item. An entity is no longer required to (1) segregate an extraordinary item from the results of ordinary operations; (2) separately present an extraordinary item on its income statement, net of tax, after income from continuing operations; and (3) disclose income taxes and earnings-per-share data applicable to an extraordinary item. This guidance does not affect the reporting and disclosure requirements for an event that is unusual in nature or that occurs infrequently. ASU No. 2015-02 (ASU 2015-02), Consolidation (Topic 810) In February 2015, the FASB issued guidance which amended the consolidation requirements in ASC 810 and significantly changed the consolidation analysis required under U.S. GAAP. The amendments include (1) limited partnerships will be variable interest entities; (2) changes the effect that fees paid to a decision maker or service provider have on the consolidation analysis; (3) amends how variable interests held by a reporting entity's related parties or de facto agents affect its consolidation conclusion; (4) clarifies how to determine whether the equity holders have power over the entity, and (5) the deferral of ASU 2009-17 for investments in certain investment funds has been eliminated. This guidance is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. The adoption of this guidance will have no impact on our consolidated financial statements as the provisions of this standard do not currently apply to CyrusOne Inc. ASU No. 2015-03 (ASU 2015-03), Imputation of Interest (Subtopic 835-30): Simplifying the Presentation of Debt Issuance Costs In April 2015, the FASB issued guidance to simplify the presentation of debt issuance costs. The amendments would require that debt issuance costs be presented in the balance sheet as a direct deduction from the carrying amount of debt liability, consistent with debt discounts or premiums. The recognition and measurement guidance for debt issuance costs would not be affected by this guidance. This guidance is effective for financial statements issued for fiscal years beginning after December 15, 2015, and interim periods within those fiscal years. Early adoption is permitted. The Company adopted this standard and debt issuance costs for all periods presented have been shown as a reduction from the carrying amount of the debt. ASU No. 2015-15 (ASU 2015-15), Imputation of Interest (Subtopic 835-30): Presentation and Subsequent Measurement of Debt Issuance Costs Associated with Line-of-Credit Arrangements In August 2015, the FASB issued ASU 2015-15 to clarify the SEC staff's position on presenting and measuring debt issuance costs incurred in connection with line-of-credit arrangements given the lack of guidance on this topic in ASU 2015-03. The SEC staff has announced that it would not object to an entity deferring issuance costs ratably over the term of the line-of-credit arrangement. The Company ratably expenses the debt issuance costs over the term of its revolving line of credit and reflects any unamortized amount as a reduction from the carrying amount of its debt. ASU No. 2015-16 (ASU 2015-16), Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments In September 2015, the FASB issued ASU 2015-16 to simplify the accounting for measurement-period adjustments. Under the ASU, an acquirer must recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The ASU also requires acquirers to present separately on the face on the income statement, or disclose in the notes, the portion of the amount recorded in the current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. This guidance is effective for fiscal years beginning after December 15, 2015, including interim periods within those fiscal years. The adoption of this standard is not expected to have a material impact on our consolidated financial statements. ASU No. 2015-17 (ASU 2015-17), Income Taxes (Topic 740) In November 2015, the FASB issued guidance which amended the balance sheet classification requirements for deferred Taxes. The ASU requires an entity to classify all deferred tax liabilities and assets as noncurrent in the balance sheet. This guidance is effective for financial statements issued for annual periods beginning after December 15, 2016, including interim periods within those fiscal years. We are currently evaluating the full impact of the new standard. ASU No. 2016-01 (ASU 2016-01), Financial instruments-Overall (Subtopic 825-10) In January 2016, the FASB amended its standards related to the accounting of certain financial instruments. This amendment addresses certain aspects of recognition, measurement, presentation and disclosure. The new rules will become effective for annual and interim periods beginning after December 15, 2017. Early adoption is not permitted. We are in the process of evaluating the impact the amendment will have on the consolidated financial statements. ASU No. 2016-02 (ASU 2016-02), Leases (Topic 842) In February 2016, the FASB issued accounting standard update (“ASU”) No. 2016-02, Leases (Topic 842). This new lease guidance requires that an entity should recognize assets and liabilities for leases with a maximum possible term of more than 12 months. A lessee would recognize a liability to make lease payments (the lease liability) and a right-of-use asset representing its right to use the leased asset (the underlying asset) for the lease term. Leases would be classified as either Type A leases (generally today’s capital leases) or Type B leases (generally today’s operating leases). For certain leases of assets other than property (for example, equipment, aircraft, cars, trucks), a lessee would classify the lease as a Type A lease and would do the following: (1) recognize a right-of-use asset and a lease liability, initially measured at the present value of lease payments and (2) recognize the unwinding of the discount on the lease liability as interest separately from the amortization of the right-of-use asset. For certain leases of property (that is, land and/or a building or part of a building), a lessee would classify the lease as a Type B lease and would do the following: (1) recognize a right-of-use asset and a lease liability, initially measured at the present value of lease payments and (2) recognize a single lease cost, combining the unwinding of the discount on the lease liability with the amortization of the right-of-use asset, on a straight-line basis. This guidance also provides accounting updates with respect to lessor accounting under a lease arrangement. This new lease guidance is effective for CyrusOne beginning in the first quarter of fiscal 2019. Entities have the option of using either a full retrospective or a modified approach (cumulative effect adjustment in period of adoption) to adopt the new guidance. Early adoption is permitted for all entities. We are currently evaluating the impact of the adoption of this guidance in our consolidated financial statements.”

Acquisitions (Tables)

Acquisitions (Tables)	12 Months Ended
	Dec. 31, 2015
Business Combinations [Abstract]
Schedule of Assets Acquired and Liabilities Assumed	The consolidated and combined financial statements include the operating results of Cervalis from the date of acquisition. The following table summarizes the estimated fair values of all assets acquired and liabilities assumed at the date of acquisition: Cash $ 1.1 Rent and other receivables 10.5 Restricted cash 8.8 Net investment in real estate 197.8 Goodwill 177.2 Customer relationships 117.4 Trade name 2.3 Other long-term assets 7.3 Total assets acquired 522.4 Current liabilities 18.3 Capital lease obligations 1.7 Long-term debt 1.5 Other arrangements 101.4 Total liabilities 122.9 Net assets acquired attributable to CyrusOne Inc. 399.5 Cash acquired (1.1 ) Net cash paid at acquisition 398.4
Pro Forma	The unaudited pro forma combined historical results of CyrusOne, as if Cervalis had been acquired and the financing transactions had been consummated as of January 1, 2014 are: IN MILLIONS For the year ended December 31, 2015 2014 Revenue 438.6 399.0 Net loss (10.9 ) (17.2 ) Loss per share - basic and diluted (0.16 ) (0.35 )

Investment in Real Estate (Tabl

Investment in Real Estate (Tables)	12 Months Ended
	Dec. 31, 2015
Real Estate [Abstract]
Schedule of Gross Investment in Real Estate	A schedule of our gross investment in real estate follows: IN MILLIONS As of December 31, 2015 2014 Land Building and Equipment Land Building and Equipment West Seventh St., Cincinnati, OH (7th Street) $ 0.9 $ 110.6 $ 19.6 $ 0.9 $ 110.6 $ 12.7 Parkway Dr., Mason, OH (Mason) — 20.2 1.0 — 20.2 0.9 Industrial Rd., Florence, KY (Florence) 2.2 41.5 3.3 2.2 41.4 3.0 Goldcoast Dr., Cincinnati, OH (Goldcoast) 0.6 6.7 0.1 0.6 6.7 0.1 Knightsbridge Dr., Hamilton, OH (Hamilton) — 49.2 4.4 — 49.2 3.7 E. Monroe St., South Bend, IN (Monroe St.) — 2.5 0.3 — 2.5 0.1 Springer St., Lombard, IL (Lombard) 0.7 4.7 7.6 0.7 4.7 5.7 Crescent Circle, South Bend, IN (Blackthorn) — 3.3 0.4 — 3.3 0.1 Kingsview Dr., Lebanon, OH (Lebanon) 4.0 77.3 7.6 4.0 77.0 5.5 McAuley Place, Blue Ash, OH (Blue Ash) — 0.6 0.1 — 0.6 0.1 Westway Park Blvd., Houston, TX (Houston West 1) 1.4 84.8 46.4 1.4 84.4 43.8 Westway Park Blvd., Houston, TX (Houston West 2) 2.0 22.6 47.1 2.0 22.5 45.1 Westway Park Blvd., Houston, TX (Houston West 3) 18.4 4.0 0.8 18.4 — — Southwest Fwy., Houston, TX (Galleria) — 68.6 16.0 — 68.6 15.0 E. Ben White Blvd., Austin, TX (Austin 1) — 13.6 1.0 — 22.5 1.2 S. State Highway 121 Business, Lewisville, TX (Lewisville) — 76.6 24.9 — 76.7 22.8 Marsh Lane, Carrollton, TX (Marsh Ln) — 0.1 0.6 — 0.1 0.5 Midway Rd., Carrollton, TX (Midway) — 2.0 0.4 — 2.0 0.4 W. Frankford Rd., Carrollton, TX (Carrollton) 16.1 52.7 116.5 16.1 51.6 85.3 Bryan St., Dallas, TX (Bryan St) — — — — 0.1 0.2 North Freeway, Houston, TX (Greenspoint) — — — — 1.3 — South Ellis Street, Chandler, AZ (Phoenix 1) 14.8 56.7 39.8 14.8 56.4 43.9 South Ellis Street, Chandler, AZ (Phoenix 2) — 16.0 39.5 — 13.2 21.8 Westover Hills Blvd., San Antonio, TX (San Antonio 1) 4.6 32.1 33.0 4.6 32.1 32.4 Westover Hills Blvd., San Antonio, TX (San Antonio 2) 7.0 — 0.1 7.0 — — Metropolis Dr., Austin, TX (Austin 2) 2.0 23.2 5.7 2.0 23.2 4.0 Myer Conners Rd (Wappinger Falls) — 11.3 14.4 — — — Madison Road (Totowa) — 28.3 48.8 — — — Commerce Road (Totowa) — 4.1 1.0 — — — Norden Place (Norwalk) — 18.3 25.4 — — — Riverbend Drive South (Stamford) — 4.3 13.2 — — — Omega Drive (Stamford) — 3.2 1.5 — — — Kestral Way (London) — 31.2 0.8 — 32.7 0.7 Jurong East (Singapore) — 8.4 0.1 — 9.0 0.1 Ridgetop Circle, Sterling, VA (Northern Virginia) 7.0 19.2 45.2 7.0 — — Metropolis Dr., Austin, TX (Austin 3) 8.0 — 0.1 8.0 — — Metropolis Dr., Austin, TX (Austin 4) 3.3 7.4 31.5 — — — Total $ 93.0 $ 905.3 $ 598.2 $ 89.7 $ 812.6 $ 349.1

Goodwill, Intangible and Othe37

Goodwill, Intangible and Other Long-Lived Assets (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 2014 Weighted- Gross Carrying Amount Accumulated Amortization Total Gross Carrying Amount Accumulated Amortization Total Customer relationships 13 $ 247.1 $ (87.5 ) $ 159.6 $ 129.7 $ (69.5 ) $ 60.2 Trademark 10 7.4 (2.7 ) 4.7 7.4 (2.3 ) 5.1 Favorable leasehold interest 49 4.1 (0.4 ) 3.7 3.9 (0.3 ) 3.6 Trade name (not amortized) 2.3 — 2.3 — — — Total $ 260.9 $ (90.6 ) $ 170.3 $ 141.0 $ (72.1 ) $ 68.9
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, 2016: IN MILLIONS 2016 $ 19.4 2017 17.3 2018 15.4 2019 13.8 2020 12.6 Thereafter 89.5 Total $ 168.0

Debt and Other Financing Arra38

Debt and Other Financing Arrangements (Tables)	12 Months Ended
	Dec. 31, 2015
Debt Disclosure [Abstract]
Debt and other financing arrangements	Debt, Capital lease obligations and Lease financing arrangements presented in the accompanying consolidated and combined financial statements consist of the following: IN MILLIONS For the year ended December 31, 2015 2014 Credit facilities: Revolving credit facility $ 235.0 $ 135.0 Term loan 300.0 150.0 6.375% senior notes due 2022, including bond premium 477.6 374.8 Notes Payable 1.5 — Deferred financing costs (17.6 ) (15.5 ) Long-term debt 996.5 644.3 Capital lease obligations 12.2 13.4 Lease financing arrangements 150.0 53.4 Total $ 1,158.7 $ 711.1
Annual minimum payments associated with our other financing arrangements	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, 2015 , and thereafter: IN MILLIONS Future Value of Payments Interest Present Value of Payments 2016 $ 17.8 $ 8.7 $ 9.1 2017 16.8 8.3 8.5 2018 14.8 7.9 6.9 2019 15.1 7.5 7.6 2020 26.0 6.8 19.2 Thereafter 127.0 28.3 98.7 Total lease financing arrangements $ 217.5 $ 67.5 $ 150.0
Schedule of annual principal maturities of our 6 3/8% Senior Notes due 2022 and capital leases	The following table summarizes aggregate maturities of revolving credit facility and term loan, 6.375% senior notes due 2022 and capital leases for the five years subsequent to December 31, 2015 , and thereafter: IN MILLIONS Revolving Credit Facility/Term Loan 6.375% Senior Notes Capital Leases Total 2016 $ — $ — $ 3.1 $ 3.1 2017 — — 1.6 1.6 2018 235.0 — 1.5 236.5 2019 300.0 — 1.6 301.6 2020 — — 1.7 1.7 Thereafter — 474.8 2.7 477.5 Total debt $ 535.0 $ 474.8 $ 12.2 $ 1,022.0

Fair Value of Financial Instr39

Fair Value of Financial Instruments (Tables)	12 Months Ended
	Dec. 31, 2015
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 For the year ended December 31, 2015 2014 Carrying Value Fair Value Carrying Value Fair Value 6.375% senior notes due 2022 $ 477.6 $ 493.8 $ 374.8 $ 402.0 Revolving credit facility and term loan 535.0 535.0 285.0 285.0 Note payable 1.5 1.2 — —
Assets Measured at Fair Value	The measured fair value used in the 2013 related impairment charges is summarized below: IN MILLIONS December 31, 2013 Quoted prices in active markets for Identical Assets (Level 1) Significant Other Observable Inputs (Level 2) Significant Unobservable Inputs (Level 3) 2013 Impairment Loss Equipment $ 0.3 $ — $ 0.3 $ — $ (2.8 ) Total impairment $ (2.8 )

Noncontrolling Interests - Op40

Noncontrolling Interests - Operating Partnership (Tables)	12 Months Ended
	Dec. 31, 2015
Noncontrolling Interest [Abstract]
Schedule of Ownership Interests in Operating Partnership	The following table shows the ownership interests as of December 31, 2015 and 2014, and the portion of net loss and distributions for the year ended December 31, 2015 and 2014: For the year ended December 31, 2015 2014 (in millions, except unit amount) The Company CBI The Company CBI Operating partnership units 72.6 — 38.7 26.6 Ownership % 100.0 % — % 59.2 % 40.8 % Portion of net loss $ (15.4 ) $ (4.8 ) $ (7.8 ) $ (6.7 ) Distributions $ (74.6 ) $ (16.3 ) $ (29.2 ) $ (25.7 )

Dividends (Tables)

Dividends (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 and 2014 as presented in the table below: Record date Payment date Cash dividend per share or operating partnership unit March 28, 2014 April 15, 2014 $0.21 June 27, 2014 July 15, 2014 $0.21 September 26, 2014 October 15, 2014 $0.21 December 26, 2014 January 9, 2015 $0.21 March 27, 2015 April 15, 2015 $0.315 June 26, 2015 July 15, 2015 $0.315 September 25, 2015 October 15, 2015 $0.315 December 24, 2015 January 8, 2016 $0.315 In 2015 and 2014, we paid all our dividends in cash. The following table summarizes the taxability of our common stock dividends per share for the year ended December 31, 2015 and December 31, 2014: For the year ended December 31, 2015 2014 Common Stock dividend per share: Ordinary income $ — $ 0.45 Return of capital 1.16 0.34 Total dividend $ 1.16 $ 0.79

Customer Leases (Tables)

Customer Leases (Tables)	12 Months Ended
	Dec. 31, 2015
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 submetered power, for the next five years are shown below: IN MILLIONS 2016 $ 379.4 2017 295.0 2018 204.1 2019 121.6 2020 81.2 At December 31, 2015 , 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 2016 $ 4.3 2017 4.2 2018 1.8 2019 — 2020 — Thereafter 0.9 Total $ 11.2

Loss per Share (Tables)

Loss per Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Income (Loss) Per Share	The following table reflects a reconciliation of the shares used in the basic and diluted net loss per share computation: IN MILLIONS, except per share amounts Year Ended Year Ended Period Ended For December 31, 2015 2014 2013 Basic Diluted Basic Diluted Basic Diluted Numerator: Net loss attributed to common shareholders $ (15.4 ) $ (15.4 ) $ (7.8 ) $ (7.8 ) $ (5.3 ) $ (5.3 ) Less: Restricted stock dividends (1.0 ) (1.0 ) (0.8 ) (0.8 ) (0.6 ) (0.6 ) Net loss available to shareholders $ (16.4 ) $ (16.4 ) $ (8.6 ) $ (8.6 ) $ (5.9 ) $ (5.9 ) Denominator: Weighted average common outstanding-basic 54.3 54.3 29.2 29.2 20.9 20.9 Performance-based restricted stock (1)(2)(3) — — — Convertible securities (1)(2)(3) — — — Weighted average shares outstanding-diluted 54.3 29.2 20.9 EPS: Net loss per share-basic $ (0.30 ) $ (0.30 ) $ (0.28 ) Effect of dilutive shares — — — Net loss per share-diluted $ (0.30 ) $ (0.30 ) $ (0.28 ) (1) We have excluded 1.9 million weighted average shares of restricted stock, and 13.1 million of weighted average operating partnership units which are securities convertible into common stock from our diluted earnings per share as of December 31, 2015 . These amounts were deemed anti-dilutive. (2) We have excluded 0.8 million weighted average shares of restricted stock, and 34.3 million of weighted average operating partnership units which are securities convertible into common stock from our diluted earnings per share as of December 31, 2014. These amounts were deemed anti-dilutive. (3) We have excluded 0.2 million weighted average shares of restricted stock, and 42.6 million of weighted average operating partnership units which are securities convertible into common stock from our diluted earnings per share as of December 31, 2013. These amounts were deemed anti-dilutive.

Stock-Based Compensation Plans

Stock-Based Compensation Plans (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 2014 2013 Founders $ 5.2 $ 5.4 $ 5.3 2013 Grants 1.2 1.2 0.9 2014 Grants 3.0 3.7 — 2015 Grants 5.0 — — Total $ 14.4 $ 10.3 $ 6.2
Schedule of Restricted Stock Awards Activity	The following table summarizes the unvested restricted stock activity and the weighted average fair value of these shares at the date of grant for the year ended December 31, 2015: For the year ended December 31, 2015 Shares Weighted Average Grant Date Fair Value Non-vested at January 1 1,739,642 $ 20.20 Granted 571,224 23.80 Vested (458,606 ) 20.90 Forfeited (266,779 ) 21.80 Non-vested at December 31 1,585,481 $ 20.99
Schedule of Unvested Stock Options	The following table summarizes the stock option activity for the year ended December 31, 2015: For the year ended December 31, 2015 Options Weighted Average Exercise Price Outstanding at January 1 166,872 $ 23.58 Granted 223,186 28.44 Exercised (2,525 ) 23.58 Forfeited or expired (53,554 ) 25.98 Outstanding at December 31 333,979 26.44 Exercisable at December 31 78,806 25.75 Vested and expected to vest 78,806 $ 25.75
Schedule of Option Valuation Assumptions	The following table summarizes the stock option assumptions for the years ended December 31, 2015, 2014, and 2013: 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 2013 $23.58 168,963 9.3 — 0.0 0.92% 3.4% 6.0 35% 2014 $23.58 166,872 8.3 13,915 8.3 0.92% 3.4% 6.0 35% 2015 $23.58 142,556 7.3 43,460 7.3 0.92% 3.4% 6.0 35% $28.42 178,704 9.1 35,346 9.1 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5% $30.74 12,719 9.6 — 0.0 1.6% - 1.75% 4.4% 5.5-6.5 32.5% - 37.5%

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	The following related party transactions are based on agreements and arrangements that were in place during the respective periods. Revenues and expenses for the periods presented were as follows: IN MILLIONS Successor Predecessor December 31, 2015 December 31, 2014 January 24, 2013 to December 31, 2013 January 1, 2013 to January 23, 2013 Revenue: Data center colocation agreement provided to CBT and CBTS $ 7.8 $ 6.4 $ 5.6 $ 0.3 229 West 7th Street lease provided to CBT 1.9 2.0 1.7 — Goldcoast Drive/Parkway (Mason) lease 0.3 0.4 0.3 — Transition services provided to CBTS (network interfaces) 0.3 0.4 0.6 0.1 Data center leases provided to CBTS 12.0 13.6 13.1 — Total revenue $ 22.3 $ 22.8 $ 21.3 $ 0.4 Operating costs and expenses: Transition services agreement by CBTS $ 0.7 $ 0.8 $ 1.3 $ — Charges for services provided by CBT (connectivity) 1.0 1.0 1.0 0.1 209 West 7th Street rent provided by CBT 0.2 0.2 0.1 — Management fees with CBI — — 0.1 — Allocated employee benefit plans by CBI — — — 0.2 Allocated centralized insurance costs by CBI — — — 0.1 Total operating costs and expenses $ 1.9 $ 2.0 $ 2.5 $ 0.4 As of December 31, 2014, the amounts receivable and payable to CBI were as follows: IN MILLIONS As of December 31, 2014 Accounts receivable from CBI $ 0.8 Accounts payable $ 1.7 Dividends payable 5.6 Total payable to CBI $ 7.3

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of taxability of common stock dividends per share	We have declared cash dividends on common shares and distributions on operating partnership units for the years ended December 31, 2015 and 2014 as presented in the table below: Record date Payment date Cash dividend per share or operating partnership unit March 28, 2014 April 15, 2014 $0.21 June 27, 2014 July 15, 2014 $0.21 September 26, 2014 October 15, 2014 $0.21 December 26, 2014 January 9, 2015 $0.21 March 27, 2015 April 15, 2015 $0.315 June 26, 2015 July 15, 2015 $0.315 September 25, 2015 October 15, 2015 $0.315 December 24, 2015 January 8, 2016 $0.315 In 2015 and 2014, we paid all our dividends in cash. The following table summarizes the taxability of our common stock dividends per share for the year ended December 31, 2015 and December 31, 2014: For the year ended December 31, 2015 2014 Common Stock dividend per share: Ordinary income $ — $ 0.45 Return of capital 1.16 0.34 Total dividend $ 1.16 $ 0.79

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
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 submetered power, for the next five years are shown below: IN MILLIONS 2016 $ 379.4 2017 295.0 2018 204.1 2019 121.6 2020 81.2 At December 31, 2015 , 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 2016 $ 4.3 2017 4.2 2018 1.8 2019 — 2020 — Thereafter 0.9 Total $ 11.2

Guarantors (Tables)

Guarantors (Tables)	12 Months Ended
	Dec. 31, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Balance Sheet	Consolidating Balance Sheets IN MILLIONS As of December 31, 2015 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Land $ — $ — $ — $ — $ 93.0 $ — $ — $ 93.0 Buildings and improvements — — — — 865.6 39.6 0.1 905.3 Equipment — — — — 594.7 0.9 2.6 598.2 Construction in progress — — — — 229.8 0.1 1.2 231.1 Subtotal — — — — 1,783.1 40.6 3.9 1,827.6 Accumulated depreciation — — — — (426.0 ) (9.6 ) — (435.6 ) Net investment in real estate — — — — 1,357.1 31.0 3.9 1,392.0 Cash and cash equivalents — — — — 10.4 3.9 — 14.3 Investment in subsidiaries 817.7 8.2 850.6 — 0.7 — (1,677.2 ) — Restricted cash — — — — 1.5 — — 1.5 Rent and other receivables — — — — 74.8 1.3 — 76.1 Intercompany receivable — — 991.3 — — — (991.3 ) — Goodwill — — — — 453.4 — — 453.4 Intangible assets, net — — — — 170.3 — — 170.3 Due from affiliates — — — — — — — — Other assets — — — — 85.3 2.7 — 88.0 Total assets $ 817.7 $ 8.2 $ 1,841.9 $ — $ 2,153.5 $ 38.9 $ (2,664.6 ) $ 2,195.6 Accounts payable and accrued expenses $ — $ — $ 29.2 — $ 106.8 $ 0.6 $ — $ 136.6 Deferred revenue — — — — 78.0 0.7 — 78.7 Intercompany payable — — — — 991.3 — (991.3 ) — Due to affiliates — — — — — — — — Capital lease obligations — — — — 6.1 6.1 — 12.2 Long-term debt — — 995.0 — 1.5 — — 996.5 Lease financing arrangements — — — — 119.2 30.8 — 150.0 Total liabilities — — 1,024.2 — 1,302.9 38.2 (991.3 ) 1,374.0 Total shareholders' equity 817.7 8.2 817.7 — 850.6 0.7 (1,673.3 ) 821.6 Noncontrolling interest — — — — — — — — Total equity 817.7 8.2 817.7 — 850.6 0.7 (1,673.3 ) 821.6 Total liabilities and equity $ 817.7 $ 8.2 $ 1,841.9 $ — $ 2,153.5 $ 38.9 $ (2,664.6 ) $ 2,195.6 IN MILLIONS As of December 31, 2014 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Land $ — $ — $ — $ — $ 89.7 $ — $ — $ 89.7 Buildings and improvements — — — — 770.9 41.7 — 812.6 Equipment — — — — 348.3 0.8 — 349.1 Construction in progress — — — — 124.8 — 2.2 127.0 Subtotal — — — — 1,333.7 42.5 2.2 1,378.4 Accumulated depreciation — — — — (319.7 ) (7.3 ) — (327.0 ) Net investment in real estate — — — — 1,014.0 35.2 2.2 1,051.4 Cash and cash equivalents — — — — 33.5 3.0 — 36.5 Investment in subsidiaries 458.5 7.1 734.3 — 3.6 — (1,203.5 ) — Rent and other receivables — — — — 57.9 3.0 — 60.9 Intercompany receivable — — 642.9 — — — (642.9 ) — Goodwill — — — — 276.2 — — 276.2 Intangible assets, net — — — — 68.9 — — 68.9 Due from affiliates — — — — 0.8 — — 0.8 Other assets — — — — 73.1 3.2 — 76.3 Total assets $ 458.5 $ 7.1 $ 1,377.2 $ — $ 1,528.0 $ 44.4 $ (1,844.2 ) $ 1,571.0 Accounts payable and accrued expenses $ — $ — $ 12.5 — $ 56.9 $ 0.5 $ — $ 69.9 Deferred revenue — — — — 65.1 0.6 — 65.7 Intercompany payable — — — — 642.9 — (642.9 ) — Due to affiliates — — 5.6 — 1.7 — — 7.3 Capital lease obligations — — — — 6.2 7.2 — 13.4 Long-term debt — — 644.3 — — — — 644.3 Lease financing arrangements — — — — 20.9 32.5 — 53.4 Total liabilities — — 662.4 — 793.7 40.8 (642.9 ) 854.0 Total shareholders' equity 458.5 7.1 714.8 — 734.3 3.6 (1,457.5 ) 460.8 Noncontrolling interest — — — — — — 256.2 256.2 Total equity 458.5 7.1 714.8 — 734.3 3.6 (1,201.3 ) 717.0 Total liabilities and equity $ 458.5 $ 7.1 $ 1,377.2 $ — $ 1,528.0 $ 44.4 $ (1,844.2 ) $ 1,571.0
Condensed Income Statement	Consolidating Statements of Operations and Comprehensive Income (Loss) IN MILLIONS Year Ended December 31, 2015 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Revenue $ — $ — $ — $ — $ 393.8 $ 5.5 $ — $ 399.3 Costs and expenses: Property operating expenses — — — — 146.0 2.7 — 148.7 Sales and marketing — — — — 12.0 0.1 — 12.1 General and administrative — — — — 46.6 — — 46.6 Depreciation and amortization — — — — 138.7 2.8 — 141.5 Transaction and acquisition integration costs — — — — 14.1 — — 14.1 Asset impairments and loss on disposal — — — — 13.5 — — 13.5 Total costs and expenses — — — — 370.9 5.6 — 376.5 Operating income (loss) — — — — 22.9 (0.1 ) — 22.8 Interest expense — — 39.7 — — 3.2 (1.7 ) 41.2 Loss on extinguishment of debt — — — — — — — — (Loss) income before income taxes — — (39.7 ) — 22.9 (3.3 ) 1.7 (18.4 ) Income tax expense — — — — (1.8 ) — — (1.8 ) Equity (loss) earnings related to investment in subsidiaries (17.1 ) (0.2 ) 17.8 — (3.3 ) — 2.8 — Net (loss) income (17.1 ) (0.2 ) (21.9 ) — 17.8 (3.3 ) 4.5 (20.2 ) Noncontrolling interest in net loss — — — — — — 4.8 4.8 Net (loss) income attributed to common shareholders (17.1 ) (0.2 ) (21.9 ) — 17.8 (3.3 ) 9.3 (15.4 ) Other comprehensive loss — — — — — (0.2 ) — (0.2 ) Comprehensive loss attributable to common shareholders $ (17.1 ) $ (0.2 ) $ (21.9 ) $ — $ 17.8 $ (3.5 ) $ 9.3 $ (15.6 ) IN MILLIONS Year Ended December 31, 2014 Parent (1) General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Revenue $ — $ — $ — $ — $ 325.1 $ 5.8 $ — $ 330.9 Costs and expenses: Property operating expenses — — — — 121.9 2.6 — 124.5 Sales and marketing — — — — 12.6 0.2 — 12.8 General and administrative — — — — 34.2 0.4 — 34.6 Depreciation and amortization — — — — 115.0 3.0 — 118.0 Transaction and acquisition integration costs — — — — 1.0 — — 1.0 Total costs and expenses — — — — 284.7 6.2 — 290.9 Operating income (loss) — — — — 40.4 (0.4 ) — 40.0 Interest expense — — 38.2 — — 3.5 (2.2 ) 39.5 Loss on extinguishment of debt — — 13.6 — — — — 13.6 (Loss) income before income taxes — — (51.8 ) — 40.4 (3.9 ) 2.2 (13.1 ) Income tax expense — — — — (1.4 ) — — (1.4 ) Equity (loss) earnings related to investment in subsidiaries (10.0 ) (0.2 ) 35.1 — (3.9 ) — (21.0 ) — Net loss (10.0 ) (0.2 ) (16.7 ) — 35.1 (3.9 ) (18.8 ) (14.5 ) Noncontrolling interest in net loss — — — — — — 6.7 6.7 Net (loss) income attributed to common shareholders (10.0 ) (0.2 ) (16.7 ) — 35.1 (3.9 ) (12.1 ) (7.8 ) Other comprehensive loss — — — — — (0.3 ) — (0.3 ) Comprehensive loss attributable to noncontrolling interests — — — — — — 0.1 0.1 Comprehensive loss attributable to common shareholders $ (10.0 ) $ (0.2 ) $ (16.7 ) $ — $ 35.1 $ (4.2 ) $ (12.0 ) $ (8.0 ) IN MILLIONS Period Ended December 31, 2013 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Revenue $ — $ — $ — $ — $ 244.3 $ 4.1 $ — $ 248.4 Costs and expenses: Property operating expenses — — — — 85.9 2.5 — 88.4 Sales and marketing — — — — 9.7 0.2 — 9.9 General and administrative — — — — 26.3 0.2 — 26.5 Depreciation and amortization — — — — 87.1 2.8 — 89.9 Restructuring charges — — — — 0.7 — — 0.7 Transaction costs — — — — 1.3 — — 1.3 Asset impairment — — — — 2.8 — — 2.8 Total costs and expenses — — — — 213.8 5.7 — 219.5 Operating loss — — — — 30.5 (1.6 ) — 28.9 Interest expense — — 36.5 — 1.8 2.9 — 41.2 Other income — — — — (0.1 ) — — (0.1 ) Loss on extinguishment of debt — — — — 1.3 — — 1.3 Loss before income taxes — — (36.5 ) — 27.5 (4.5 ) — (13.5 ) Income tax expense — — — — (1.9 ) — — (1.9 ) Equity loss related to investment in subsidiaries (5.3 ) (0.2 ) 20.9 — (4.5 ) — (10.9 ) — Loss on sale of real estate improvements — — — — (0.2 ) — — (0.2 ) Net loss (5.3 ) (0.2 ) (15.6 ) — 20.9 (4.5 ) (10.9 ) (15.6 ) Noncontrolling interest in net loss — — — — — — (10.3 ) (10.3 ) Net income (loss) attributed to common shareholders $ (5.3 ) $ (0.2 ) $ (15.6 ) $ — $ 20.9 $ (4.5 ) $ (0.6 ) $ (5.3 ) IN MILLIONS Period Ended January 23, 2013 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Revenue $ — $ — $ — $ — $ 14.9 $ 0.2 $ — $ 15.1 Costs and expenses: Property operating expenses — — — — 4.8 — — 4.8 Sales and marketing — — — — 0.7 — — 0.7 General and administrative — — — — 1.4 0.1 — 1.5 Transaction-related compensation — — — — 20.0 — — 20.0 Depreciation and amortization — — — — 5.2 0.1 — 5.3 Transaction costs — — — — 0.1 — — 0.1 Total costs and expenses — — — — 32.2 0.2 — 32.4 Operating (loss) income — — — — (17.3 ) — — (17.3 ) Interest expense — — 2.3 — 0.1 0.1 — 2.5 Loss before income taxes — — (2.3 ) — (17.4 ) (0.1 ) — (19.8 ) Income tax expense — — — — (0.4 ) — — (0.4 ) Equity loss related to investment in subsidiaries — — (17.9 ) — (0.1 ) — 18.0 — Net loss $ — $ — $ (20.2 ) $ — $ (17.9 ) $ (0.1 ) $ 18.0 $ (20.2 )
Condensed Cash Flow Statement	Consolidating Statements of Cash Flows IN MILLIONS Year Ended December 31, 2015 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Net (loss) income $ (17.1 ) (0.2 ) $ (21.9 ) $ — 17.8 $ (3.3 ) $ 4.5 $ (20.2 ) Equity earnings (loss) related to investment in subsidiaries 17.1 0.2 (17.8 ) — 3.3 — (2.8 ) — Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities: Depreciation and amortization — — — — 138.7 2.8 — 141.5 Stock-based compensation expense — — — — 14.4 — — 14.4 Non-cash interest expense — — 3.4 — — — — 3.4 Provision for bad debt write off — — — — — — — — Loss on extinguishment of debt — — — — — — — — Asset impairments and loss on disposal — — — — 13.5 — — 13.5 Changes in operating assets and liabilities: Rent receivables and other assets — — — — (26.1 ) 2.2 — (23.9 ) Accounts payable and accrued expenses — — 16.7 — (9.8 ) 0.1 — 7.0 Deferred revenues — — — — 5.3 0.1 — 5.4 Due to affiliates — — — — (0.9 ) — — (0.9 ) Net cash (used in) provided by operating activities — — (19.6 ) — 156.2 1.9 1.7 140.2 Cash flows from investing activities: Capital expenditures - acquisitions of real estate — — — — (17.3 ) — — (17.3 ) Capital expenditures - other development — — — — (216.7 ) (0.5 ) — (217.2 ) Business acquisition, net of cash acquired — — — — (398.4 ) — — (398.4 ) Release of restricted cash — — — — 7.3 — — 7.3 Investment in and loans to subsidiaries (203.1 ) (2.0 ) (203.1 ) — (0.4 ) — 408.6 — Return of investment 62.6 — 102.0 — (17.9 ) — (146.7 ) — Intercompany contributions/distributions — — (348.4 ) — — — 348.4 — Net cash provided by (used in) investing activities (140.5 ) (2.0 ) (449.5 ) — (643.4 ) (0.5 ) 610.3 (625.6 ) Cash flows from financing activities: Issuance of common stock 799.5 — — — — — — 799.5 Stock issuance costs (0.8 ) — — — — — — (0.8 ) Acquisition of operating partnership units (596.4 ) — — — — — — (596.4 ) Dividends paid (61.0 ) — (80.8 ) — (80.8 ) — 141.8 (80.8 ) Intercompany borrowings — — — — 348.4 — (348.4 ) — Borrowings from credit facility — — 260.0 — — — — 260.0 Proceeds from issuance of debt — — 103.8 — — — — 103.8 Payments on credit facility — — (10.0 ) — — — — (10.0 ) Payments on senior notes — — — — — — — — Payments on capital leases and other financing arrangements — — — — (5.0 ) (0.9 ) — (5.9 ) Tax payment upon exercise of equity awards (0.8 ) — — — — — — (0.8 ) Contributions from/(distributions to) parent, net — 2.0 201.5 — 201.5 0.4 (405.4 ) — Debt issuance costs — — (5.4 ) — — — — (5.4 ) Net cash (used in) provided by financing activities 140.5 2.0 469.1 — 464.1 (0.5 ) (612.0 ) 463.2 Net (decrease) increase in cash and cash equivalents — — — — (23.1 ) 0.9 — (22.2 ) Cash and cash equivalents at beginning of period — — — — 33.5 3.0 — 36.5 Cash and cash equivalents at end of period $ — $ — $ — $ — $ 10.4 $ 3.9 $ — $ 14.3 IN MILLIONS Year Ended December 31, 2014 Parent Guarantor General Partner LP Co-issuer Finance Co-issuer Guarantor Subsidiaries Non- Guarantors Eliminations/Consolidations Total Net (loss) income $ (10.0 ) (0.2 ) $ (16.7 ) $ — 35.1 $ (3.9 ) $ (18.8 ) $ (14.5 ) Equity earnings (loss) related to investment in subsidiaries 10.0 0.2 (35.1 ) — 3.9 — 21.0 — Adjustments to reconcile net (loss) income to net cash provided by (used in) operating activities: Depreciation and amortization — — — — 115.0 3.0 — 118.0 Stock-based compensation expense — — — — 10.3 — — 10.3 Non-cash interest expense — — 3.4 — — — — 3.4 Provision for bad debt write off — — — — 0.8 — — 0.8 Loss on extinguishment of debt — — 13.6 — — — — 13.6 Changes in operating assets and liabilities: Rent receivables and other assets — — 0.4 — (35.3 ) (2.1 ) — (37.0 ) Accounts payable and accrued expenses — — 4.7 — 2.1 0.1 — 6.9 Due to affiliates — — — — (0.2 ) — — (0.2 ) Deferred revenues — — — — 10.0 (0.2 ) — 9.8 Net cash provided by (used in) operating activities — — (29.7 ) — 141.7 (3.1 ) 2.2 111.1 Cash flows from investing activities: Capital expenditures - other development — — — — (283.9 ) (0.3 ) — (284.2 ) Return of investment 25.2 — 97.3 — (45.4 ) — (77.1 ) — Intercompany receipts — — 180.2 — — — (180.2 ) — Intercompany distributions — — (315.0 ) — — — 315.0 — Net cash (used in) provided by investing activities 25.2 — (37.5 ) — (329.3 ) (0.3 ) 57.7 (284.2 ) Cash flows from financing activities: Issuance of common stock 356.0 — — — — — — 356.0 Stock issuance costs (1.3 ) — — — — — — (1.3 ) Acquisition of operating partnership units (355.9 ) — — — — — — (355.9 ) Dividends paid (24.0 ) — (50.9 ) — (50.9 ) — 74.9 (50.9 ) Intercompany borrowings — — — — 315.0 — (315.0 ) — Intercompany payments — — — — (180.2 ) — 180.2 — Borrowings from credit facility — — 315.0 — — — — 315.0 Payments on credit facility — — (30.0 ) — — — — (30.0 ) Payments on senior notes — — (150.2 ) — — — — (150.2 ) Payments on capital leases obligations — — — — (2.4 ) (0.6 ) — (3.0 ) Payments on financing arrangements — — — — (0.7 ) (0.2 ) — (0.9 ) Payment of debt extinguishment costs — — (12.8 ) — — — — (12.8 ) Contributions from/(distributions to) parent, net — — 1.3 — (6.5 ) 5.2 — — Debt issuance costs — — (5.2 ) — — — — (5.2 ) Net cash provided by (used in) financing activities (25.2 ) — 67.2 — 74.3 4.4 (59.9 ) 60.8 Net (decrease) increase in cash and cash equivalents — — — — (113.3 ) 1.0 — (112.3 ) Cash and cash equivalents at beginning of period — — — — 146.8 2.0 — 148.8 Cash and cash equivalents at end of period $ — $ — $ — $ — $ 33.5 $ 3.0 $ — $ 36.5 IN MILLIONS Period Ended December 31, 2013 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Net (loss) income $ (5.3 ) $ (0.2 ) $ (15.6 ) $ — $ 20.9 $ (4.5 ) $ (10.9 ) $ (15.6 ) Equity loss related to investment in subsidiaries 5.3 0.2 (20.9 ) — 4.5 — 10.9 — Adjustments to reconcile net (loss) income to net cash provided by operating activities: Depreciation and amortization — — — — 87.1 2.8 — 89.9 Stock-based compensation expense — — — — 6.0 — — 6.0 Non-cash interest expense — — 4.0 — — — — 4.0 Provision for bad debt write off — — — — 0.4 — — 0.4 Loss on extinguishment of debt — — — — 1.3 — — 1.3 Asset impairments and loss on disposal — — — — 2.8 — — 2.8 Deferred income tax expense, including valuation allowance change — — — — 0.6 — — 0.6 Other, net (7.1 ) — (13.4 ) — (16.2 ) — 36.7 — Changes in operating assets and liabilities: Rent receivables and other assets 9.4 — — — (9.9 ) (3.0 ) (12.2 ) (15.7 ) Accounts payable and accrued expenses (2.3 ) — 4.8 — 0.2 0.3 (17.6 ) (14.6 ) Due to affiliates — — 6.8 — 18.4 — (6.8 ) 18.4 Deferred revenues — — — — (0.3 ) 0.2 — (0.1 ) Net cash provided by operating activities — — (34.3 ) — 115.8 (4.2 ) 0.1 77.4 Cash flows from investing activities: Capital expenditures - acquisitions of real estate — — — — (48.0 ) — — (48.0 ) Capital expenditures - other development — — — — (172.9 ) — — (172.9 ) Investment in subsidiaries (337.1 ) — (337.1 ) — — — 674.2 — Release of restricted cash — — — — 4.4 — — 4.4 Return of investment 10.6 — 66.5 — — — (77.1 ) — Other — — — — (0.2 ) — — (0.2 ) Net cash provided by (used in) investing activities (326.5 ) — (270.6 ) — (216.7 ) — 597.1 (216.7 ) Cash flows from financing activities: Issuance of common stock/partnership units 360.5 — 337.1 — — — (337.1 ) 360.5 IPO costs (23.4 ) — — — (3.2 ) — — (26.6 ) Dividends paid (10.6 ) — (31.0 ) — (31.0 ) — 41.6 (31.0 ) Payments on capital leases — — — — (4.4 ) (0.9 ) — (5.3 ) Payments on financing obligations — — — — (0.5 ) (0.2 ) — (0.7 ) Payment to buyout capital leases — — — — (9.6 ) — — (9.6 ) Payment to buyout other financing arrangements — — — — (10.2 ) — — (10.2 ) Contributions from parent guarantor — — — — 295.4 6.3 (301.7 ) — Debt issuance costs — — (1.3 ) — — — — (1.3 ) Net cash provided by (used in) financing activities 326.5 — 304.8 — 236.5 5.2 (597.2 ) 275.8 Net increase (decrease) in cash and cash equivalents — — (0.1 ) — 135.6 1.0 — 136.5 Cash and cash equivalents at beginning of period — — 0.1 — 11.2 1.0 — 12.3 Cash and cash equivalents at end of period $ — $ — $ — $ — $ 146.8 $ 2.0 $ — $ 148.8 IN MILLIONS Period Ended January 23, 2013 Parent General LP Finance Guarantor Subsidiaries Non- Eliminations/Consolidations Total Net (loss) income $ — $ — $ (20.2 ) $ — $ (17.9 ) $ (0.1 ) $ 18.0 $ (20.2 ) Equity loss related to investment in subsidiaries — — 17.9 — 0.1 — (18.0 ) — Adjustments to reconcile net (loss) income to net cash provided by operating activities — — 0.2 — 5.6 0.1 — 5.9 Changes in operating assets and liabilities: Rent receivables and other assets — — — — (9.6 ) — — (9.6 ) Accounts payable and accrued expenses — — 2.1 — 18.4 — — 20.5 Due to affiliates — — — — 1.5 — — 1.5 Other changes in assets and liabilities — — — — 3.8 0.1 — 3.9 Net cash provided by operating activities — — — — 1.9 0.1 — 2.0 Cash flows from investing activities: Capital expenditures - other development — — — — (7.7 ) — — (7.7 ) Release of restricted cash — — — — 1.9 — — 1.9 Intercompany advances, net — — 0.1 — (0.1 ) — — — Net cash provided by (used in) investing activities — — 0.1 — (5.9 ) — — (5.8 ) Cash flows from financing activities: Payments on capital lease obligations — — — — (0.6 ) — — (0.6 ) Contributions from/(distributions to) parent, net — — — — 0.2 — — 0.2 Net cash used in financing activities — — — — (0.4 ) — — (0.4 ) Net increase (decrease) in cash and cash equivalents — — 0.1 — (4.4 ) 0.1 — (4.2 ) Cash and cash equivalents at beginning of period — — — — 15.6 0.9 — 16.5 Cash and cash equivalents at end of period $ — $ — $ 0.1 $ — $ 11.2 $ 1.0 $ — $ 12.3

Quarterly Financial Informati49

Quarterly Financial Information (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2015
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, 2015 and 2014 : IN MILLIONS, except per share amounts 2015 First Quarter Second Quarter Third Quarter Fourth Total Revenue $ 85.7 $ 89.1 $ 111.2 $ 113.3 $ 399.3 Operating income 1.6 2.6 7.5 11.1 22.8 Net income (loss) (7.2 ) (6.5 ) (5.3 ) (1.2 ) (20.2 ) Net income (loss) attributed to common shareholders (4.3 ) (5.5 ) (4.6 ) (1.0 ) (15.4 ) Basic and diluted loss per share (a) $ (0.12 ) $ (0.11 ) $ (0.08 ) $ (0.02 ) $ (0.33 ) IN MILLIONS, except per share amounts 2014 First Second Quarter Third Quarter Fourth Quarter Total Revenue $ 77.5 $ 81.7 $ 84.8 $ 86.9 $ 330.9 Operating (loss) income 11.8 7.4 9.6 11.2 40.0 Net loss 0.7 (3.6 ) 0.2 (11.8 ) (14.5 ) Net loss attributed to common shareholders 0.2 (1.1 ) 0.1 (7.0 ) (7.8 ) Basic and diluted loss per share (b) $ — $ (0.06 ) $ — $ (0.19 ) $ (0.25 ) (a) The basic and diluted income (loss) per share for 2015 was $(0.30) compared to $(0.33) due to the impact of the 14.3 million shares of common stock issued during the secondary offering in April 2015, and the 6.0 million shares of common stock issued during the secondary offering in June 2015. (b) The basic and diluted income (loss) per share for 2014 was $(0.30) compared to $(0.25) due to the impact of the 16.0 million shares of common stock issued during the secondary offering in June 2014.

Description of Business - Narra

Description of Business - Narrative (Details) - Dec. 31, 2015	recovery_center	data_center
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of data operating centers	2	32

Formation and Recent Developm51

Formation and Recent Developments - Narrative (Details) $ / shares in Units, $ in Millions	Dec. 31, 2015shares	Dec. 14, 2015shares	Jul. 01, 2015USD ($)data_centerwork_recoveryshares	Jun. 26, 2015USD ($)$ / sharesshares	Apr. 07, 2015USD ($)$ / sharesshares	Jun. 25, 2014USD ($)$ / sharesshares	Jan. 24, 2013USD ($)shares	Nov. 20, 2012shares	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)
Business Formation [Line Items]
Common stock issued (in shares)										200,000
Partners' capital units converted (in shares)							1,500,000
Proceeds from exchange of partnership units							1,500,000
Number of common shares issued to directors and employees							1,100,000
Shares purchased of Operating partnership's units			6,000,000		14,300,000	16,000,000	21,900,000
Combined interest held on completion of transactions							33.90%
Purchase of Operating partnership's units | $							$ 337.1
Ownership percentage by noncontrolling owners	0.00%									0.00%	40.80%
Issuance of common stock | $									$ 360.5	$ 799.5	$ 356
IPO
Business Formation [Line Items]
Common stock issued (in shares)	6,346,835	1,350,000		13,000,000	14,300,000	16,000,000	19,000,000
Net proceeds from IPO after underwriting discounts and commissions | $				$ 373.3	$ 443.8	$ 371.7	$ 337.1
Share price (in dollars per share) | $ / shares						$ 23.25
Net proceeds from IPO after underwriting discounts and commissions | $			$ 170.3		426	$ 355.9
Underwriting discount | $				$ 16.6	$ 17.8	$ 15.8
Over-Allotment Option
Business Formation [Line Items]
Common stock issued (in shares)					1,900,000	2,100,000
Share price (in dollars per share) | $ / shares				$ 30	$ 31.12
Cincinnati Bell Inc.
Business Formation [Line Items]
Operating partnership units owned (in shares)							44,100,000
Remaining combined interest held							66.10%
Ownership percentage by noncontrolling owners	9.50%									9.50%
CyrusOne L.P.
Business Formation [Line Items]
Issuance of partnership units (in shares)							400,000	123,700,000
Partnership reverse unit split, conversion ratio							2.8
Operating partnership units	72,600,000									72,600,000
Cervalis
Business Formation [Line Items]
Data centers acquired | data_center			4
Work area recovery facilities acquired | work_recovery			2
Maximum | Cervalis
Business Formation [Line Items]
Total consideration for acquisition | $			$ 398.4

Significant Accounting Polici52

Significant Accounting Policies - Narrative (Details)	1 Months Ended	3 Months Ended	11 Months Ended	12 Months Ended
	Jan. 23, 2013USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)customersegment	Dec. 31, 2014USD ($)customer	Dec. 31, 2013USD ($)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Foreign currency translation adjustments				$ (200,000)	$ (300,000)
Summary Of Significant Accounting Policies [Line Items]
Percentage of lease term				75.00%
Percentage of lease payment				90.00%
Capitalized interest				$ (6,100,000)	(4,600,000)	$ (1,600,000)
Asset impairments and loss on disposal			$ 2,800,000	13,500,000	0	2,800,000
Impairment of goodwill				0	0
Unbilled receivables				6,500,000
deferred leasing costs				14,200,000	12,800,000
Straight-line rents receivable				44,700,000	33,700,000
Deferred revenue				78,700,000	65,700,000
Advertising expense	$ 100,000		2,100,000	2,200,000	2,900,000
Depreciation	4,100,000		70,300,000	117,800,000	95,800,000
Amortization expense for intangible assets subject to amortization	1,200,000		$ 19,600,000	23,700,000	22,200,000
Transaction-related compensation	20,000,000
Unrecognized tax benefits				$ 0	$ 0
Number of segments | segment				1
Cincinnati Bell Inc.
Summary Of Significant Accounting Policies [Line Items]
Transaction-related compensation	$ 20,000,000
Trademark
Summary Of Significant Accounting Policies [Line Items]
Weighted- Average Remaining Life (in years)				10 years
Customer relationships
Summary Of Significant Accounting Policies [Line Items]
Weighted- Average Remaining Life (in years)				13 years
Customer Concentration Risk | Receivables
Summary Of Significant Accounting Policies [Line Items]
Number of customers that exceed 10% of total receivables | customer				1	1
Minimum
Summary Of Significant Accounting Policies [Line Items]
Receivables due term				30 days
Deferred leasing costs amortization term				3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Receivables due term				120 days
Deferred leasing costs amortization term				5 years
Buildings | Minimum
Summary Of Significant Accounting Policies [Line Items]
Useful life				9 years
Buildings | Maximum
Summary Of Significant Accounting Policies [Line Items]
Useful life				30 years
Building Improvements | Minimum
Summary Of Significant Accounting Policies [Line Items]
Useful life				3 years
Building Improvements | Maximum
Summary Of Significant Accounting Policies [Line Items]
Useful life				30 years
Equipment
Summary Of Significant Accounting Policies [Line Items]
Asset impairments and loss on disposal		$ 2,800,000
Equipment | Minimum
Summary Of Significant Accounting Policies [Line Items]
Useful life				3 years
Equipment | Maximum
Summary Of Significant Accounting Policies [Line Items]
Useful life				20 years
Land
Summary Of Significant Accounting Policies [Line Items]
Lease term of favorable leasehold interest which being amortized				51 years
Adjustment for Inaccurate Attribution of Non-controlling Interest for Other Comprehensive Income (Loss)
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Comprehensive loss attributable to noncontrolling interests					$ (6,700,000)	(10,300,000)
Adjustment for Inaccurate Attribution of Foreign Currency Transaction to Non-controlling Interest
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Foreign currency translation adjustments					$ 100,000	$ 100,000

Acquisitions - Narrative (Detai

Acquisitions - Narrative (Details) $ in Millions	Jul. 01, 2015USD ($)data_centerwork_recovery	Dec. 31, 2015USD ($)	Dec. 31, 2015USD ($)
Cervalis
Business Acquisition [Line Items]
Percent of company acquired	100.00%
Acquisition costs			$ 12.9
Revenue of acquiree since acquisition		$ 37.7
Data centers acquired | data_center	4
Work area recovery facilities acquired | work_recovery	2
Customer relationships
Business Acquisition [Line Items]
Weighted- Average Remaining Life (in years)			13 years
Customer relationships | Cervalis
Business Acquisition [Line Items]
Weighted- Average Remaining Life (in years)	15 years
Maximum | Cervalis
Business Acquisition [Line Items]
Total consideration for acquisition	$ 398.4

Acquisitions - Assets Acquired

Acquisitions - Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Millions	Jul. 01, 2015	Dec. 31, 2015	Dec. 31, 2014
Business Acquisition [Line Items]
Goodwill		$ 453.4	$ 276.2
Cervalis
Business Acquisition [Line Items]
Cash	$ 1.1
Rent and other receivables	10.5
Restricted cash	8.8
Net investment in real estate	197.8
Goodwill	177.2
Customer relationships	117.4
Trade name	2.3
Other long-term assets	7.3
Total assets acquired	522.4
Current liabilities	18.3
Capital lease obligations	1.7
Long-term debt	1.5
Other arrangements	101.4
Total liabilities	122.9
Net assets acquired attributable to CyrusOne Inc.	399.5
Cash acquired	(1.1)
Net cash paid at acquisition	$ 398.4

Acquisitions - Pro Forma (Detai

Acquisitions - Pro Forma (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Business Combinations [Abstract]
Revenue	$ 438.6	$ 399
Net loss	$ (10.9)	$ (17.2)
Loss per share - basic and diluted (in USD per share)	$ (0.16)	$ (0.35)

Investment in Real Estate - Sch

Investment in Real Estate - Schedule of Gross Investment in Real Estate (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Real Estate Properties [Line Items]
Land	$ 93	$ 89.7
Building and Improvements	905.3	812.6
Equipment	598.2	349.1
West Seventh St., Cincinnati, OH (7th Street)
Real Estate Properties [Line Items]
Land	0.9	0.9
Building and Improvements	110.6	110.6
Equipment	19.6	12.7
Parkway Dr., Mason, OH (Mason)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	20.2	20.2
Equipment	1	0.9
Industrial Rd., Florence, KY (Florence)
Real Estate Properties [Line Items]
Land	2.2	2.2
Building and Improvements	41.5	41.4
Equipment	3.3	3
Goldcoast Dr., Cincinnati, OH (Goldcoast)
Real Estate Properties [Line Items]
Land	0.6	0.6
Building and Improvements	6.7	6.7
Equipment	0.1	0.1
Knightsbridge Dr., Hamilton, OH (Hamilton)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	49.2	49.2
Equipment	4.4	3.7
E. Monroe St., South Bend, IN (Monroe St.)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	2.5	2.5
Equipment	0.3	0.1
Springer St., Lombard, IL (Lombard)
Real Estate Properties [Line Items]
Land	0.7	0.7
Building and Improvements	4.7	4.7
Equipment	7.6	5.7
Crescent Circle, South Bend, IN (Blackthorn)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	3.3	3.3
Equipment	0.4	0.1
Kingsview Dr., Lebanon, OH (Lebanon)
Real Estate Properties [Line Items]
Land	4	4
Building and Improvements	77.3	77
Equipment	7.6	5.5
McAuley Place, Blue Ash, OH (Blue Ash)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	0.6	0.6
Equipment	0.1	0.1
Westway Park Blvd., Houston, TX (Houston West 1)
Real Estate Properties [Line Items]
Land	1.4	1.4
Building and Improvements	84.8	84.4
Equipment	46.4	43.8
Westway Park Blvd., Houston, TX (Houston West 2)
Real Estate Properties [Line Items]
Land	2	2
Building and Improvements	22.6	22.5
Equipment	47.1	45.1
Westway Park Blvd., Houston, TX (Houston West 3)
Real Estate Properties [Line Items]
Land	18.4	18.4
Building and Improvements	4	0
Equipment	0.8	0
Southwest Fwy., Houston, TX (Galleria)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	68.6	68.6
Equipment	16	15
E. Ben White Blvd., Austin, TX (Austin 1)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	13.6	22.5
Equipment	1	1.2
S. State Highway 121 Business, Lewisville, TX (Lewisville)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	76.6	76.7
Equipment	24.9	22.8
Marsh Lane, Carrollton, TX (Marsh Ln)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	0.1	0.1
Equipment	0.6	0.5
Midway Rd., Carrollton, TX (Midway)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	2	2
Equipment	0.4	0.4
W. Frankford Rd., Carrollton, TX (Carrollton)
Real Estate Properties [Line Items]
Land	16.1	16.1
Building and Improvements	52.7	51.6
Equipment	116.5	85.3
Bryan St., Dallas, TX (Bryan St)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	0	0.1
Equipment	0	0.2
North Freeway, Houston, TX (Greenspoint)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	0	1.3
Equipment	0	0
South Ellis Street, Chandler, AZ (Phoenix 1)
Real Estate Properties [Line Items]
Land	14.8	14.8
Building and Improvements	56.7	56.4
Equipment	39.8	43.9
South Ellis Street, Chandler, AZ (Phoenix 2)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	16	13.2
Equipment	39.5	21.8
Westover Hills Blvd., San Antonio, TX (San Antonio 1)
Real Estate Properties [Line Items]
Land	4.6	4.6
Building and Improvements	32.1	32.1
Equipment	33	32.4
Westover Hills Blvd., San Antonio, TX (San Antonio 2)
Real Estate Properties [Line Items]
Land	7	7
Building and Improvements	0	0
Equipment	0.1	0
Metropolis Dr., Austin, TX (Austin 2)
Real Estate Properties [Line Items]
Land	2	2
Building and Improvements	23.2	23.2
Equipment	5.7	4
Myer Conners Rd (Wappinger Falls)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	11.3	0
Equipment	14.4	0
Madison Road (Totowa)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	28.3	0
Equipment	48.8	0
Commerce Road (Totowa)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	4.1	0
Equipment	1	0
Norden Place (Norwalk)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	18.3	0
Equipment	25.4	0
Riverbend Drive South (Stamford)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	4.3	0
Equipment	13.2	0
Omega Drive (Stamford)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	3.2	0
Equipment	1.5	0
Kestral Way (London)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	31.2	32.7
Equipment	0.8	0.7
Jurong East (Singapore)
Real Estate Properties [Line Items]
Land	0	0
Building and Improvements	8.4	9
Equipment	0.1	0.1
Ridgetop Circle, Sterling, VA (Northern Virginia)
Real Estate Properties [Line Items]
Land	7	7
Building and Improvements	19.2	0
Equipment	45.2	0
Metropolis Dr., Austin, TX (Austin 3)
Real Estate Properties [Line Items]
Land	8	8
Building and Improvements	0	0
Equipment	0.1	0
Metropolis Dr., Austin, TX (Austin 4)
Real Estate Properties [Line Items]
Land	3.3	0
Building and Improvements	7.4	0
Equipment	$ 31.5	$ 0

Investment in Real Estate - Nar

Investment in Real Estate - Narrative (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 23, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Real Estate Properties [Line Items]
Payments to Acquire Real Estate Held-for-investment		$ 48	$ 17.3
Payments to Acquire Other Property, Plant, and Equipment	$ 7.7	172.9	217.2	$ 284.2
Asset impairments and loss on disposal		2.8	13.5	0	$ 2.8
Cost of construction in progress			231.1	127
Successor
Real Estate Properties [Line Items]
Payments to Acquire Real Estate Held-for-investment		48	17.3	0
Payments to Acquire Other Property, Plant, and Equipment		172.9	217.2	284.2
Asset impairments and loss on disposal		$ 2.8	13.5	$ 0
Metropolis Dr., Austin, TX (Austin 4)
Real Estate Properties [Line Items]
Payments to Acquire Real Estate Held-for-investment			17.3
Metropolis Dr., Austin, TX (Austin 4) | Buildings
Real Estate Properties [Line Items]
Payments to Acquire Real Estate Held-for-investment			17.3
Metropolis Dr., Austin, TX (Austin 4) | Land
Real Estate Properties [Line Items]
Payments to Acquire Real Estate Held-for-investment			$ 3.3

Goodwill, Intangible and Othe58

Goodwill, Intangible and Other Long-Lived Assets - Narrative (Details) - USD ($)	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 23, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Jul. 01, 2015
Business Acquisition [Line Items]
Goodwill			$ 453,400,000	$ 276,200,000
Impairment of long-lived and intangible assets			0	0
Impairment of goodwill			0	0
Amortization expense for intangible assets subject to amortization	$ 1,000,000	$ 15,900,000	18,500,000	$ 17,000,000
Cervalis
Business Acquisition [Line Items]
Goodwill					$ 177,200,000
Goodwill acquired			177,200,000
Cervalis | Customer relationships
Business Acquisition [Line Items]
Finite-lived intangible assets acquired			117,400,000
Cervalis | Trademark
Business Acquisition [Line Items]
Finite-lived intangible assets acquired			2,300,000
Cervalis | Leases, Acquired-in-Place
Business Acquisition [Line Items]
Finite-lived intangible assets acquired			$ 200,000

Goodwill, Intangible and Othe59

Goodwill, Intangible and Other Long-Lived Assets - Carrying Value of Major Classes of Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization	$ (90.6)	$ (72.1)
Total	168
Gross total indefinite and finite-lived intangible assets	260.9	141
Total indefinite and finite-lived intangible assets	170.3	68.9
Trademark
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 2.3	0
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Weighted- Average Remaining Life (in years)	13 years
Finite gross carrying amount	$ 247.1	129.7
Accumulated Amortization	(87.5)	(69.5)
Total	$ 159.6	60.2
Trademark
Finite-Lived Intangible Assets [Line Items]
Weighted- Average Remaining Life (in years)	10 years
Finite gross carrying amount	$ 7.4	7.4
Accumulated Amortization	(2.7)	(2.3)
Total	$ 4.7	5.1
Favorable leasehold interest
Finite-Lived Intangible Assets [Line Items]
Weighted- Average Remaining Life (in years)	49 years
Finite gross carrying amount	$ 4.1	3.9
Accumulated Amortization	(0.4)	(0.3)
Total	$ 3.7	$ 3.6

Goodwill, Intangible and Othe60

Goodwill, Intangible and Other Long-Lived Assets - Estimated Amortization Expense For Finite-Lived Intangible Assets (Details) $ in Millions	Dec. 31, 2015USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2,016	$ 19.4
2,017	17.3
2,018	15.4
2,019	13.8
2,020	12.6
Thereafter	89.5
Total	$ 168

Debt and Other Financing Arra61

Debt and Other Financing Arrangements - Debt and Capital Lease Obligations (Details) - USD ($)	Dec. 31, 2015	Jun. 22, 2015	Dec. 31, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long-term debt	$ 996,500,000		$ 644,300,000
Deferred financing costs	(17,600,000)		(15,500,000)
Capital lease obligations	12,200,000		13,400,000
Lease financing arrangements	150,000,000		53,400,000
Total	$ 1,158,700,000		$ 711,100,000
6.375% senior notes due 2022, including bond premium
Debt Instrument [Line Items]
Stated interest rate	6.375%		6.375%
6.375% Senior Notes | 6.375% senior notes due 2022, including bond premium
Debt Instrument [Line Items]
Long-term debt	$ 477,600,000		$ 374,800,000
Stated interest rate	6.375%
Notes Payable
Debt Instrument [Line Items]
Long-term debt			0
Revolving credit facility
Debt Instrument [Line Items]
Revolving credit facility	$ 235,000,000	$ 650,000,000	135,000,000	$ 0
Term loan
Debt Instrument [Line Items]
Revolving credit facility	$ 300,000,000		$ 150,000,000

Debt and Other Financing Arra62

Debt and Other Financing Arrangements - Capital Lease Obligations (Details) $ in Millions	Dec. 31, 2015USD ($)
Future Value of Payments
2,016	$ 17.8
2,017	16.8
2,018	14.8
2,019	15.1
2,020	26
Thereafter	127
Total lease financing arrangements	217.5
Interest
2,016	8.7
2,017	8.3
2,018	7.9
2,019	7.5
2,020	6.8
Thereafter	28.3
Total lease financing arrangements	67.5
2,016	9.1
2,017	8.5
2,018	6.9
2,019	7.6
2,020	19.2
Thereafter	98.7
Total lease financing arrangements	$ 150

Debt and Other Financing Arra63

Debt and Other Financing Arrangements - Maturities of Debt (Details) $ in Millions	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
2,015	$ 3.1
2,016	1.6
2,017	236.5
2,018	301.6
2,019	1.7
Thereafter	477.5
Long-term Debt	1,022
Revolving Credit Facility/Term Loan
Debt Instrument [Line Items]
2,015	0
2,016	0
2,017	235
2,018	300
2,019	0
Thereafter	0
Long-term Debt	535
6.375% Senior Notes
Debt Instrument [Line Items]
2,015	0
2,016	0
2,017	0
2,018	0
2,019	0
Thereafter	474.8
Long-term Debt	474.8
Capital Leases
Debt Instrument [Line Items]
2,015	3.1
2,016	1.6
2,017	1.5
2,018	1.6
2,019	1.7
Thereafter	2.7
Long-term Debt	$ 12.2

Debt and Other Financing Arra64

Debt and Other Financing Arrangements - Narrative (Details)	Jul. 01, 2015USD ($)	Jun. 22, 2015USD ($)	Nov. 20, 2012USD ($)	Jan. 23, 2013USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)data_centerpurchase_option	Dec. 31, 2014USD ($)	Oct. 09, 2014USD ($)	Oct. 08, 2014USD ($)
Debt Instrument [Line Items]
Long-term debt					$ 644,300,000		$ 996,500,000	$ 644,300,000
Interest expense on capital lease obligations				$ 300,000		$ 6,300,000	$ 7,800,000	5,900,000
Total unencumbered assets							150.00%
Lease financing arrangements					53,400,000		$ 150,000,000	53,400,000
Deferred financing costs					$ 15,500,000		17,600,000	15,500,000
Amortization of deferred financing costs				$ 100,000		4,000,000	$ 3,400,000	3,400,000
Additional amortization due to extinguishment of debt								$ 800,000
Number of data centers under capital lease | data_center							4
Option to purchase leased assets | purchase_option							1
2,016							$ 17,800,000
2,017							16,800,000
2,018							14,800,000
2,019							15,100,000
2,020							26,000,000
Thereafter							$ 127,000,000
6.375% senior notes due 2022, including bond premium
Debt Instrument [Line Items]
Stated interest rate					6.375%		6.375%	6.375%
Term Loan
Debt Instrument [Line Items]
Face amount of debt		$ 300,000,000							$ 150,000,000
Remaining borrowing capacity		$ 250,000,000
Long-term debt					$ 150,000,000			$ 150,000,000
Term Loan | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		1.65%
6.375% Senior Notes | 6.375% senior notes due 2022, including bond premium
Debt Instrument [Line Items]
Long-term debt					374,800,000		$ 477,600,000	374,800,000
Stated interest rate							6.375%
Premium on debt	$ 3,800,000
Number of days to register	180 days
Repurchased face amount					150,200,000			150,200,000
Repurchase amount					163,000,000			163,000,000
Loss on repurchase of notes					12,800,000
Proceeds from Issuance of Private Placement	$ 100,000,000
6.375% Senior Notes | 6.375% senior notes due 2022, including bond premium | Cyrus One Lp And Cyrus One Finance Corp
Debt Instrument [Line Items]
Long-term debt			$ 525,000,000
Stated interest rate			6.375%				6.375%
Percentage of redemption price			100.00%
Percentage of senior notes declining redemption 1			103.188%
Percentage of senior notes declining redemption 2			102.125%
Percentage of senior notes declining redemption 3			101.063%
Percentage of senior notes declining redemption 4			100.00%
Percentage of Redemption of the aggregate principal			35.00%
Percentage of equity offering on principal amount			106.375%
Percentage of Redemption of the least aggregate principal			65.00%
Term of redemption occurs			90 days
Notes Payable
Debt Instrument [Line Items]
Long-term debt					0			0
Periodic payment							$ 9,000
Revolving credit facility
Debt Instrument [Line Items]
Credit agreement amount									$ 450,000,000	$ 225,000,000
Increase (decrease) in credit facility		$ 350,000,000
Term of extension option		1 year
Outstanding borrowings on revolving credit agreement		$ 650,000,000			$ 135,000,000	$ 0	$ 235,000,000	135,000,000
Commitment fee percent							0.25%
Commitment fee amount							$ 900,000	$ 1,100,000
Maximum percentage of dividends allowed to be distributed							95.00%
Revolving credit facility | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on variable rate		1.70%
Revolving credit facility | First Amendment to Credit Agreement
Debt Instrument [Line Items]
Credit agreement amount		$ 600,000,000
Optional additional borrowing capacity		300,000,000
Revolving credit facility | Second Amendment to Credit Agreement
Debt Instrument [Line Items]
Credit agreement amount		950,000,000
Optional additional borrowing capacity		$ 600,000,000
Interest on Capital Leases
Debt Instrument [Line Items]
2,016							$ 1,000,000
2,017							800,000
2,018							700,000
2,019							500,000
2,020							400,000
Thereafter							$ 400,000

Fair Value of Financial Instr65

Fair Value of Financial Instruments - Carrying and Fair Value (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 996.5	$ 644.3
6.375% Senior Notes | 6.375% senior notes due 2022, including bond premium
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	477.6	374.8
6.375% Senior Notes | Reported Value Measurement | 6.375% senior notes due 2022, including bond premium
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	477.6	374.8
6.375% Senior Notes | Estimate of Fair Value Measurement | 6.375% senior notes due 2022, including bond premium
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	493.8	402
Line of Credit | Reported Value Measurement | Revolving Credit Facility/Term Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	535	285
Line of Credit | Estimate of Fair Value Measurement | Revolving Credit Facility/Term Loan
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	535	285
Notes Payable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt		0
Notes Payable | Reported Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	1.5	0
Notes Payable | Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt	$ 1.2	$ 0

Fair Value of Financial Instr66

Fair Value of Financial Instruments - Assets Measured at Fair Value (Details) - USD ($) $ in Millions	3 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset impairments and loss on disposal		$ (2.8)	$ (13.5)	$ 0	$ (2.8)
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset impairments and loss on disposal					(2.8)
Equipment
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Asset impairments and loss on disposal	$ (2.8)
Equipment | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long-lived intangible assets	0.3	0.3			0.3
Asset impairments and loss on disposal					(2.8)
Equipment | Fair Value, Measurements, Nonrecurring | Quoted prices in active markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long-lived intangible assets	0	0			0
Equipment | Fair Value, Measurements, Nonrecurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long-lived intangible assets	0.3	0.3			0.3
Equipment | Fair Value, Measurements, Nonrecurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of long-lived intangible assets	$ 0	$ 0			$ 0

Fair Value of Financial Instr67

Fair Value of Financial Instruments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	11 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset impairments and loss on disposal		$ 2.8	$ 13.5	$ 0	$ 2.8
Equipment
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Book value of assets	$ 3.1	$ 3.1			$ 3.1
Equipment purchased	0.3
Asset impairments and loss on disposal	$ 2.8
6.375% senior notes due 2022, including bond premium
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate			6.375%	6.375%
6.375% Senior Notes | 6.375% senior notes due 2022, including bond premium
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Stated interest rate			6.375%

Noncontrolling Interests - Op68

Noncontrolling Interests - Operating Partnership (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 14, 2015	Jun. 26, 2015	Apr. 07, 2015	Jun. 25, 2014	Jan. 24, 2013	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Noncontrolling Interest [Line Items]
Ownership %	100.00%						100.00%				59.20%					100.00%	59.20%
Ownership percentage by noncontrolling owners	0.00%						0.00%				40.80%					0.00%	40.80%
Net loss attributed to common shareholders							$ (1)	$ (4.6)	$ (5.5)	$ (4.3)	$ (7)	$ 0.1	$ (1.1)	$ 0.2	$ (5.3)	$ (15.4)	$ (7.8)	$ (5.3)
Noncontrolling interest in net loss															(10.3)	(4.8)	(6.7)
Dividends declared															(41.4)	$ (90.9)	$ (54.9)
Rate partnership units are converted (in shares)																1
Common stock issued (in shares)																200,000
Cincinnati Bell Inc.
Noncontrolling Interest [Line Items]
Ownership percentage by noncontrolling owners	9.50%						9.50%									9.50%
IPO
Noncontrolling Interest [Line Items]
Common stock issued (in shares)	6,346,835	1,350,000	13,000,000	14,300,000	16,000,000	19,000,000
Parent
Noncontrolling Interest [Line Items]
Operating partnership units	72,600,000						72,600,000				38,700,000					72,600,000	38,700,000
Noncontrolling interest in net loss															10.3	$ 4.8	$ 6.7
Dividends declared															(13.6)	$ (74.6)	$ (29.2)
Non Controlling Interest
Noncontrolling Interest [Line Items]
Operating partnership units	0						0				26,600,000					0	26,600,000
Noncontrolling interest in net loss															(10.3)	$ (4.8)	$ (6.7)
Dividends declared															$ (27.8)	$ (16.3)	$ (25.7)

Dividends (Details)

Dividends (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 23, 2016	Jan. 08, 2016	Oct. 15, 2015	Jul. 15, 2015	Apr. 15, 2015	Jan. 09, 2015	Oct. 15, 2014	Jul. 15, 2014	Apr. 15, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Dividends Payable [Line Items]
Cash dividend per share or operating partnership unit (in dollars per share)			$ 0.315	$ 0.315	$ 0.315	$ 0.21	$ 0.21	$ 0.21	$ 0.21		$ 1.16	$ 0.79
Dividends payable											$ 24.4	$ 14.3
Dividends declared per share (in dollars per share)										$ 0.64	$ 1.26	$ 0.84
Subsequent Event
Dividends Payable [Line Items]
Cash dividend per share or operating partnership unit (in dollars per share)		$ 0.315
Dividends declared per share (in dollars per share)	$ 0.38

Customer Leases - Narrative (De

Customer Leases - Narrative (Details) $ in Millions	Dec. 31, 2014USD ($)
Leases [Abstract]
2,016	$ 379.4
2,017	295
2,018	204.1
2,019	121.6
2,020	$ 81.2

Employee Benefit Plans (Details

Employee Benefit Plans (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 23, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
CyrusOne Health Care Plan
Defined Contribution Plan [Line Items]
Other Labor-related Expenses	$ 0.1	$ 1.6	$ 3.1	$ 2.1
Retirement Savings Plan
Defined Contribution Plan [Line Items]
Retirement savings plan contributions (less than $0.5 million and $0.1 million)	$ 0.1	$ 0.5	$ 1.1	$ 0.8

Loss per Share - Computation of

Loss per Share - Computation of Basic and Diluted Net Income (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								11 Months Ended	12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Numerator:
Net loss attributed to common shareholders	$ (1)	$ (4.6)	$ (5.5)	$ (4.3)	$ (7)	$ 0.1	$ (1.1)	$ 0.2	$ (5.3)	$ (15.4)	$ (7.8)	$ (5.3)
Less: Restricted stock dividends										(1)	(0.8)	(0.6)
Less: Restricted stock dividends										(1)	(0.8)	(0.6)
Net loss available to stockholders, Basic										(16.4)	(8.6)	(5.9)
Net loss available to stockholders, Diluted										$ (16.4)	$ (8.6)	$ (5.9)
Denominator:
Weighted average common outstanding - basic (in shares)										54.3	29.2	20.9
Performance-based restricted stock (in shares)										0	0	0
Convertible securities (in shares)										0	0	0
Weighted average shares outstanding- diluted (in shares)										54.3	29.2	20.9
EPS:
Net loss per share- basic (in dollars per share)										$ (0.30)	$ (0.30)	$ (0.28)
Effect of dilutive shares (in dollars per share)										0	0	0
Loss per share - diluted (in dollars per share)										$ (0.30)	$ (0.30)	$ (0.28)
Restricted Stock
EPS:
Anti-dilutive securities excluded from diluted earning per share (in shares)										1.9	0.8	0.2
Operating Partnership Units
EPS:
Anti-dilutive securities excluded from diluted earning per share (in shares)										13.1	34.3	42.6

Stock-Based Compensation Plan73

Stock-Based Compensation Plans - Allocated Share-based Compensation Expense (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	$ 14.4	$ 10.3	$ 6.2
Founders
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	5.2	5.4	5.3
2013 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	1.2	1.2	0.9
2014 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	3	3.7	0
2015 Grants
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Total compensation expense	$ 5	$ 0	$ 0

Stock-Based Compensation Plan74

Stock-Based Compensation Plans - Other Than Options (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Shares
Unvested balance (in shares)	1,739,642	1,126,669
Granted (in shares)	571,224
Vested (in shares)	(458,606)
Forfeited (in shares)	(266,779)
Unvested balance (in shares)	1,585,481	1,739,642
Weighted Average Fair Value at Date of Grant
Unvested balance (in dollars per share)	$ 20.20
Granted (in dollars per share)	23.80
Vested (in dollars per share)	20.90
Forfeited (in dollars per share)	21.80
Unvested balance (in dollars per share)	$ 20.99	$ 20.20

Stock-Based Compensation Plan75

Stock-Based Compensation Plans - Options (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Shares of Restricted Options
Beginning balance (in shares)	166,872	168,963
Granted (in shares)	223,186
Exercised (in shares)	(2,525)	0	0
Forfeited or expired (in shares)	(53,554)
Ending balance (in shares)	333,979	166,872	168,963
Exercisable (in shares)	78,806
Vested and expected to vest (in shares)	78,806
Weighted Average Fair Value at Date of Grant
Beginning balance (in dollars per share)	$ 23.58
Granted (in dollars per share)	28.44
Exercised (in dollars per share)	23.58
Forfeited or expired (in dollars per share)	25.98
Ending balance (in dollars per share)	26.44	$ 23.58
Exercisable (in dollars per share)	25.75
Vested and expected to vest (in dollars per share)	$ 25.75

Stock-Based Compensation Plan76

Stock-Based Compensation Plans - Option Valuation Assumptions (Details) - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares (in shares)	333,979	166,872	168,963
Exercisable (in shares)	78,806
$ 23.58
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in dollars per share)			$ 23.58
Number of shares (in shares)			168,963
Weighted average outstanding contractual term (in years)			9 years 3 months 18 days
Exercisable (in shares)			0
Weighted average exercisable contractual term (in years)			0 years
Expected annual dividend			3.40%
Risk-free rate			0.92%
Expected term (in years)			6 years
Expected volatility			35.00%
$ 23.58
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in dollars per share)		$ 23.58
Number of shares (in shares)		166,872
Weighted average outstanding contractual term (in years)		8 years 3 months 18 days
Exercisable (in shares)		13,915
Weighted average exercisable contractual term (in years)		8 years 3 months 18 days
Expected annual dividend		3.40%
Risk-free rate		0.92%
Expected term (in years)		6 years
Expected volatility		35.00%
$ 23.58
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in dollars per share)	$ 23.58
Number of shares (in shares)	142,556
Weighted average outstanding contractual term (in years)	7 years 3 months 18 days
Exercisable (in shares)	43,460
Weighted average exercisable contractual term (in years)	7 years 3 months 18 days
Expected annual dividend	3.40%
Risk-free rate	0.92%
Expected term (in years)	6 years
Expected volatility	35.00%
$ 28.42
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in dollars per share)	$ 28.42
Number of shares (in shares)	178,704
Weighted average outstanding contractual term (in years)	9 years 1 month 6 days
Exercisable (in shares)	35,346
Weighted average exercisable contractual term (in years)	9 years 1 month 6 days
Expected annual dividend	4.40%
$ 30.74
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price (in dollars per share)	$ 30.74
Number of shares (in shares)	12,719
Weighted average outstanding contractual term (in years)	9 years 7 months 6 days
Exercisable (in shares)	0
Weighted average exercisable contractual term (in years)	0 years
Expected annual dividend	4.40%
Minimum | $28.42
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.60%
Expected term (in years)	5 years 6 months
Expected volatility	32.50%
Minimum | $30.74
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.60%
Expected term (in years)	5 years 6 months
Expected volatility	32.50%
Maximum | $28.42
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.75%
Expected term (in years)	6 years 6 months
Expected volatility	37.50%
Maximum | $30.74
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free rate	1.75%
Expected term (in years)	6 years 6 months
Expected volatility	37.50%

Stock-Based Compensation Plan77

Stock-Based Compensation Plans - Narrative (Details) $ / shares in Units, $ in Millions	Feb. 10, 2015	Feb. 07, 2014	Apr. 17, 2013$ / shares	Jan. 24, 2013USD ($)shares	Dec. 31, 2015USD ($)executiveshares	Dec. 31, 2014USD ($)shares	Dec. 31, 2013USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)					223,186
Number of shares (in shares)					333,979	166,872	168,963
Exercised (in dollars per share)					2,525	0	0
Intrinsic value of options outstanding | $					$ 3.7
Intrinsic value of options exercisable | $					$ 0.9
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options issued (in shares)					571,224
Unvested balance (in shares)					1,585,481	1,739,642	1,126,669
2012 LTIP Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares authorized (in shares)					4,000,000
Shares available for grant (in shares)					1,500,000
Founders | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options issued (in shares)				1,000,000
Other than options grant date value | $				$ 19
Award vesting period				3 years
Unrecognized compensation expense, other than options | $					$ 0.3
Unrecognized compensation expense, period for recognition					1 month 6 days
2013 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average exercise price for options granted | $ / shares			$ 23.58
2013 Grants | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options issued (in shares)							4,361
Other than options grant date value | $							$ 0.1
Award vesting period							3 years
Unrecognized compensation expense, other than options | $					$ 0.1
Unrecognized compensation expense, period for recognition					3 months 18 days
2013 Grants | Restricted Stock | Cliff Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period							1 year
2013 Grants | Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Award vesting rights percentage			50.00%
2013 Grants | Performance Awards | Below 90% of EBITDA Target
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			0.00%
2013 Grants | Performance Awards | At 90% of EBITDA Target
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			50.00%
2013 Grants | Performance Awards | At 100% of EBITDA Target
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			100.00%
2013 Grants | Performance Awards | At or above 115% of EBITDA Target
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage			200.00%
2013 Grants | Market based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Award vesting rights percentage			50.00%
Measurement period			3 years
2013 Grants | 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%
2013 Grants | 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%
2013 Grants | 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%
2013 Grants | 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%
2013 Grants | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration period for award			10 years
2014 Grants | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options issued (in shares)						46,313
Other than options grant date value | $						$ 1
Award vesting period						3 years
Unrecognized compensation expense, other than options | $					$ 1.3
Unrecognized compensation expense, period for recognition					1 year 1 month 6 days
2014 Grants | Restricted Stock | Cliff Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period						1 year
2014 Grants | Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Award vesting rights percentage		50.00%
Performance period		3 years
2014 Grants | Market based restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period		3 years
Award vesting rights percentage		50.00%
2015 Grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation expense, other than options | $					$ 5.6
Unrecognized compensation expense, period for recognition					1 year 7 months 6 days
2015 Grants | Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options issued (in shares)					29,424
Award vesting period	3 years
Award vesting rights percentage	25.00%
2015 Grants | Restricted Stock | Cliff Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options issued (in shares)					8,157
Award vesting period					3 years
2015 Grants | Performance and market based awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights percentage	75.00%
2015 Grants | Performance Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options issued (in shares)					11,711
Measurement period	3 years
Performance period					3 years
Cap on award vesting	100.00%
2015 Grants | Performance Awards | Cliff Vesting
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other than options issued (in shares)					55,301
Performance period					3 years
2015 Grants | Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period	3 years
Granted (in shares)					12,719
2015 Grants | Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Accelerated compensation cost | $					$ 2.4
Number of individuals with accelerated vesting | executive					2

Related Party Transactions - Sc

Related Party Transactions - Schedule of Related Party Revenue and Expenses (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 23, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Successor
Revenue:
Total revenue		$ 21.3	$ 22.3	$ 22.8
Operating costs and expenses:
Total operating costs and expenses		2.5	1.9	2
Successor | Data center colocation agreement provided to CBT and CBTS
Revenue:
Total revenue		5.6	7.8	6.4
Successor | 229 West 7th Street lease provided to CBT
Revenue:
Total revenue		1.7	1.9	2
Successor | Goldcoast Drive/Parkway (Mason) lease
Revenue:
Total revenue		0.3	0.3	0.4
Successor | Transition services provided to CBTS (network interfaces)
Revenue:
Total revenue		0.6	0.3	0.4
Successor | Data center leases provided to CBTS
Revenue:
Total revenue		13.1	12	13.6
Successor | Transition services agreement by CBTS
Operating costs and expenses:
Total operating costs and expenses		1.3	0.7	0.8
Successor | Charges for services provided by CBT (connectivity)
Operating costs and expenses:
Total operating costs and expenses		1	1	1
Successor | 209 West 7th Street rent provided by CBT
Operating costs and expenses:
Total operating costs and expenses		0.1	0.2	0.2
Successor | Management fees with CBI
Operating costs and expenses:
Total operating costs and expenses		0.1	0	0
Successor | Allocated employee benefit plans by CBI
Operating costs and expenses:
Total operating costs and expenses		0	0	0
Successor | Allocated centralized insurance costs by CBI
Operating costs and expenses:
Total operating costs and expenses		$ 0	$ 0	$ 0
Predecessor
Revenue:
Total revenue	$ 0.4
Operating costs and expenses:
Total operating costs and expenses	0.4
Predecessor | Data center colocation agreement provided to CBT and CBTS
Revenue:
Total revenue	0.3
Predecessor | 229 West 7th Street lease provided to CBT
Revenue:
Total revenue	0
Predecessor | Goldcoast Drive/Parkway (Mason) lease
Revenue:
Total revenue	0
Predecessor | Transition services provided to CBTS (network interfaces)
Revenue:
Total revenue	0.1
Predecessor | Data center leases provided to CBTS
Revenue:
Total revenue	0
Predecessor | Transition services agreement by CBTS
Operating costs and expenses:
Total operating costs and expenses	0
Predecessor | Charges for services provided by CBT (connectivity)
Operating costs and expenses:
Total operating costs and expenses	0.1
Predecessor | 209 West 7th Street rent provided by CBT
Operating costs and expenses:
Total operating costs and expenses	0
Predecessor | Management fees with CBI
Operating costs and expenses:
Total operating costs and expenses	0
Predecessor | Allocated employee benefit plans by CBI
Operating costs and expenses:
Total operating costs and expenses	0.2
Predecessor | Allocated centralized insurance costs by CBI
Operating costs and expenses:
Total operating costs and expenses	$ 0.1

Related Party Transactions - 79

Related Party Transactions - Schedule of Due to/Due From Related Party (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Related Party Transactions [Abstract]
Accounts receivable from CBI	$ 0	$ 0.8
Accounts payable		1.7
Dividends payable		5.6
Total payable to CBI		$ 7.3

Related Party Transactions - Na

Related Party Transactions - Narrative (Details) - USD ($) shares in Millions, $ in Millions	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Dividends payable	$ 24.4	$ 24.4	$ 14.3
Common stock issued (in shares)		0.2
CyrusOne LP
Related Party Transaction [Line Items]
Dividends payable	$ 2	$ 2
Common stock issued (in shares)	6.3
Bosselaw
Related Party Transaction [Line Items]
Expenses to related party				$ 1.6
Jones Lang LaSalle
Related Party Transaction [Line Items]
Expenses to related party		$ 1.1	1	1.5
Skadden
Related Party Transaction [Line Items]
Expenses to related party			$ 1.1	$ 0.2

Restructuring Charges - Narrati

Restructuring Charges - Narrative (Details) - USD ($) $ in Millions	11 Months Ended	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2013
Restructuring and Related Activities [Abstract]
Restructuring charges	$ 0.7	$ 0.7

Income Taxes - Narrative (Detai

Income Taxes - Narrative (Details)	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 23, 2013USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2015USD ($)Subsidiary	Dec. 31, 2014USD ($)
Income Taxes [Line Items]
Number of REIT subsidiaries | Subsidiary			2
Income tax expense (benefit)	$ 400,000	$ 1,900,000	$ 1,800,000	$ 1,400,000
Texas margin tax payable			0	1,700,000
Total deferred tax assets			$ 0	$ 0
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%

Income Taxes - Dividends Paid (

Income Taxes - Dividends Paid (Details) - $ / shares	Oct. 15, 2015	Jul. 15, 2015	Apr. 15, 2015	Jan. 09, 2015	Oct. 15, 2014	Jul. 15, 2014	Apr. 15, 2014	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Ordinary income								$ 0	$ 0.45
Return of capital								1.16	0.34
Total dividend	$ 0.315	$ 0.315	$ 0.315	$ 0.21	$ 0.21	$ 0.21	$ 0.21	$ 1.16	$ 0.79

Commitments and Contingencies -

Commitments and Contingencies - Operating Leases (Details) $ in Millions	Dec. 31, 2014USD ($)
Commitments and Contingencies Disclosure [Abstract]
2,016	$ 4.3
2,017	4.2
2,018	1.8
2,019	0
2,020	0
Thereafter	0.9
Total	$ 11.2

Commitments and Contingencies85

Commitments and Contingencies - Narrative (Details) - USD ($)	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 23, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Rent expense	$ 200,000	$ 6,500,000	$ 7,400,000	$ 6,700,000
Letters of credit outstanding			7,100,000
Performance Guarantee
Loss Contingencies [Line Items]
Loss contingency accrual			0	$ 0
Services
Purchase Commitment, Excluding Long-term Commitment [Line Items]
Amount of minimum purchase commitment			$ 42,600,000
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

Guarantors - Narrative (Details

Guarantors - Narrative (Details) - USD ($)	Jul. 01, 2015	Apr. 07, 2015	Jun. 25, 2014	Jan. 24, 2013	Dec. 31, 2015	Dec. 31, 2014	Nov. 20, 2012
Condensed Financial Statements, Captions [Line Items]
Long-term debt					$ 996,500,000	$ 644,300,000
Combined interest held on completion of transactions				33.90%
Parent Guarantor
Condensed Financial Statements, Captions [Line Items]
Long-term debt					$ 0	0
Combined interest held on completion of transactions				33.90%
CyrusOne GP
Condensed Financial Statements, Captions [Line Items]
Combined interest held on completion of transactions					1.00%
Non- Guarantors
Condensed Financial Statements, Captions [Line Items]
Long-term debt					$ 0	$ 0
Parent Company's Ownership Percentage					100.00%
6.375% senior notes due 2022, including bond premium
Condensed Financial Statements, Captions [Line Items]
Stated interest rate					6.375%	6.375%
6.375% senior notes due 2022, including bond premium | CyrusOne GP
Condensed Financial Statements, Captions [Line Items]
Ownership Percentage of Senior Notes					100.00%
6.375% Senior Notes | 6.375% senior notes due 2022, including bond premium
Condensed Financial Statements, Captions [Line Items]
Long-term debt					$ 477,600,000	$ 374,800,000
Stated interest rate					6.375%
6.375% Senior Notes | 6.375% senior notes due 2022, including bond premium | Cyrus One Lp And Cyrus One Finance Corp
Condensed Financial Statements, Captions [Line Items]
Long-term debt							$ 525,000,000
Stated interest rate					6.375%		6.375%
IPO
Condensed Financial Statements, Captions [Line Items]
Net proceeds from IPO after underwriting discounts and commissions	$ 170,300,000	$ 426,000,000	$ 355,900,000
IPO | Parent Guarantor
Condensed Financial Statements, Captions [Line Items]
Net proceeds from IPO after underwriting discounts and commissions				$ 337,100,000

Guarantors - Balance Sheet (Det

Guarantors - Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Jan. 23, 2013	Dec. 31, 2012
Condensed Consolidating Balance Sheets
Land	$ 93	$ 89.7
Buildings and improvements	905.3	812.6
Equipment	598.2	349.1
Construction in progress	231.1	127
Subtotal	1,827.6	1,378.4
Accumulated depreciation	(435.6)	(327)
Net investment in real estate	(1,392)	(1,051.4)
Cash and cash equivalents	14.3	36.5	$ 148.8	$ 12.3	$ 16.5
Investment in subsidiaries	0	0
Restricted cash	1.5	0
Rent and other receivables	76.1	60.9
Intercompany receivable	0	0
Goodwill	453.4	276.2
Intangible assets, net	170.3	68.9
Due from affiliates	0	0.8
Other assets	88	76.3
Total assets	2,195.6	1,571
Accounts payable and accrued expenses	136.6	69.9
Deferred revenue	78.7	65.7
Intercompany payable	0	0
Due to affiliates	0	7.3
Capital lease obligations	12.2	13.4
Long-term debt	996.5	644.3
Lease financing arrangements	150	53.4
Total liabilities	1,374	854
Total shareholders’ equity	821.6	460.8
Noncontrolling interest	0	256.2
Total equity	821.6	717	777.6		500.1
Total liabilities and equity	2,195.6	1,571
Eliminations/Consolidations
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	0.1	0
Equipment	2.6	0
Construction in progress	1.2	2.2
Subtotal	3.9	2.2
Accumulated depreciation	0	0
Net investment in real estate	(3.9)	(2.2)
Cash and cash equivalents	0	0	0	0	0
Investment in subsidiaries	(1,677.2)	(1,203.5)
Restricted cash	0
Rent and other receivables	0	0
Intercompany receivable	(991.3)	(642.9)
Goodwill	0	0
Intangible assets, net	0	0
Due from affiliates	0	0
Other assets	0	0
Total assets	(2,664.6)	(1,844.2)
Accounts payable and accrued expenses	0	0
Deferred revenue	0	0
Intercompany payable	(991.3)	(642.9)
Due to affiliates	0	0
Capital lease obligations	0	0
Long-term debt	0	0
Lease financing arrangements	0	0
Total liabilities	(991.3)	(642.9)
Total shareholders’ equity	(1,673.3)	(1,457.5)
Noncontrolling interest	0	256.2
Total equity	(1,673.3)	(1,201.3)
Total liabilities and equity	(2,664.6)	(1,844.2)
Parent Guarantor
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	0	0
Equipment	0	0
Construction in progress	0	0
Subtotal	0	0
Accumulated depreciation	0	0
Net investment in real estate	0	0
Cash and cash equivalents	0	0	0	0	0
Investment in subsidiaries	817.7	458.5
Restricted cash	0
Rent and other receivables	0	0
Intercompany receivable	0	0
Goodwill	0	0
Intangible assets, net	0	0
Due from affiliates	0	0
Other assets	0	0
Total assets	817.7	458.5
Accounts payable and accrued expenses	0	0
Deferred revenue	0	0
Intercompany payable	0	0
Due to affiliates	0	0
Capital lease obligations	0	0
Long-term debt	0	0
Lease financing arrangements	0	0
Total liabilities	0	0
Total shareholders’ equity	817.7	458.5
Noncontrolling interest	0	0
Total equity	817.7	458.5
Total liabilities and equity	817.7	458.5
LP Co-issuer
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	0	0
Equipment	0	0
Construction in progress	0	0
Subtotal	0	0
Accumulated depreciation	0	0
Net investment in real estate	0	0
Cash and cash equivalents	0	0	0	0.1	0
Investment in subsidiaries	850.6	734.3
Restricted cash	0
Rent and other receivables	0	0
Intercompany receivable	991.3	642.9
Goodwill	0	0
Intangible assets, net	0	0
Due from affiliates	0	0
Other assets	0	0
Total assets	1,841.9	1,377.2
Accounts payable and accrued expenses	29.2	12.5
Deferred revenue	0	0
Intercompany payable	0	0
Due to affiliates	0	5.6
Capital lease obligations	0	0
Long-term debt	995	644.3
Lease financing arrangements	0	0
Total liabilities	1,024.2	662.4
Total shareholders’ equity	817.7	714.8
Noncontrolling interest	0	0
Total equity	817.7	714.8
Total liabilities and equity	1,841.9	1,377.2
Finance Co-issuer
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	0	0
Equipment	0	0
Construction in progress	0	0
Subtotal	0	0
Accumulated depreciation	0	0
Net investment in real estate	0	0
Cash and cash equivalents	0	0	0	0	0
Investment in subsidiaries	0	0
Restricted cash	0
Rent and other receivables	0	0
Intercompany receivable	0	0
Goodwill	0	0
Intangible assets, net	0	0
Due from affiliates	0	0
Other assets	0	0
Total assets	0	0
Accounts payable and accrued expenses	0	0
Deferred revenue	0	0
Intercompany payable	0	0
Due to affiliates	0	0
Capital lease obligations	0	0
Long-term debt	0	0
Lease financing arrangements	0	0
Total liabilities	0	0
Total shareholders’ equity	0	0
Noncontrolling interest	0	0
Total equity	0	0
Total liabilities and equity	0	0
Guarantor Subsidiaries
Condensed Consolidating Balance Sheets
Land	93	89.7
Buildings and improvements	865.6	770.9
Equipment	594.7	348.3
Construction in progress	229.8	124.8
Subtotal	1,783.1	1,333.7
Accumulated depreciation	(426)	(319.7)
Net investment in real estate	(1,357.1)	(1,014)
Cash and cash equivalents	10.4	33.5	146.8	11.2	15.6
Investment in subsidiaries	0.7	3.6
Restricted cash	1.5
Rent and other receivables	74.8	57.9
Intercompany receivable	0	0
Goodwill	453.4	276.2
Intangible assets, net	170.3	68.9
Due from affiliates	0	0.8
Other assets	85.3	73.1
Total assets	2,153.5	1,528
Accounts payable and accrued expenses	106.8	56.9
Deferred revenue	78	65.1
Intercompany payable	991.3	642.9
Due to affiliates	0	1.7
Capital lease obligations	6.1	6.2
Long-term debt	1.5	0
Lease financing arrangements	119.2	20.9
Total liabilities	1,302.9	793.7
Total shareholders’ equity	850.6	734.3
Noncontrolling interest	0	0
Total equity	850.6	734.3
Total liabilities and equity	2,153.5	1,528
Non- Guarantors
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	39.6	41.7
Equipment	0.9	0.8
Construction in progress	0.1	0
Subtotal	40.6	42.5
Accumulated depreciation	(9.6)	(7.3)
Net investment in real estate	(31)	(35.2)
Cash and cash equivalents	3.9	3	2	1	0.9
Investment in subsidiaries	0	0
Restricted cash	0
Rent and other receivables	1.3	3
Intercompany receivable	0	0
Goodwill	0	0
Intangible assets, net	0	0
Due from affiliates	0	0
Other assets	2.7	3.2
Total assets	38.9	44.4
Accounts payable and accrued expenses	0.6	0.5
Deferred revenue	0.7	0.6
Intercompany payable	0	0
Due to affiliates	0	0
Capital lease obligations	6.1	7.2
Long-term debt	0	0
Lease financing arrangements	30.8	32.5
Total liabilities	38.2	40.8
Total shareholders’ equity	0.7	3.6
Noncontrolling interest	0	0
Total equity	0.7	3.6
Total liabilities and equity	38.9	44.4
General Partner
Condensed Consolidating Balance Sheets
Land	0	0
Buildings and improvements	0	0
Equipment	0	0
Construction in progress	0	0
Subtotal	0	0
Accumulated depreciation	0	0
Net investment in real estate	0	0
Cash and cash equivalents	0	0	$ 0	$ 0	$ 0
Investment in subsidiaries	8.2	7.1
Restricted cash	0
Rent and other receivables	0	0
Intercompany receivable	0	0
Goodwill	0	0
Intangible assets, net	0	0
Due from affiliates	0	0
Other assets	0	0
Total assets	8.2	7.1
Accounts payable and accrued expenses	0	0
Deferred revenue	0	0
Intercompany payable	0	0
Due to affiliates	0	0
Capital lease obligations	0	0
Long-term debt	0	0
Lease financing arrangements	0	0
Total liabilities	0	0
Total shareholders’ equity	8.2	7.1
Noncontrolling interest	0	0
Total equity	8.2	7.1
Total liabilities and equity	$ 8.2	$ 7.1

Guarantors - Income Statement (

Guarantors - Income Statement (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended								11 Months Ended	12 Months Ended
	Jan. 23, 2013	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Consolidating Statements of Operations
Revenue	$ 15.1	$ 113.3	$ 111.2	$ 89.1	$ 85.7	$ 86.9	$ 84.8	$ 81.7	$ 77.5	$ 248.4	$ 399.3	$ 330.9
Costs and expenses:
Property operating expenses	4.8									88.4	148.7	124.5
Sales and marketing	0.7									9.9	12.1	12.8
General and administrative	1.5									26.5	46.6	34.6
Transaction-related compensation	20
Depreciation and amortization	5.3									89.9	141.5	118
Restructuring charges										0.7			$ 0.7
Transaction and acquisition integration costs	0.1									1.3	14.1	1
Asset impairments and loss on disposal										2.8	13.5	0	2.8
Total costs and expenses	32.4									219.5	376.5	290.9
Operating income (loss)	(17.3)	11.1	7.5	2.6	1.6	11.2	9.6	7.4	11.8	28.9	22.8	40
Interest expense	2.5									41.2	41.2	39.5
Loss on extinguishment of debt										1.3	0	13.6
Other income										(0.1)
Net loss before income taxes	(19.8)									(13.5)	(18.4)	(13.1)
Income tax expense	(0.4)									(1.9)	(1.8)	(1.4)
Equity loss related to investment in subsidiaries	0									0	0	0
Loss on sale of real estate improvements										(0.2)
Net loss	(20.2)	(1.2)	(5.3)	(6.5)	(7.2)	(11.8)	0.2	(3.6)	0.7	(15.6)	(20.2)	(14.5)
Noncontrolling interest in net loss										10.3	4.8	6.7
Net loss attributed to common shareholders		$ (1)	$ (4.6)	$ (5.5)	$ (4.3)	$ (7)	$ 0.1	$ (1.1)	$ 0.2	(5.3)	(15.4)	(7.8)	$ (5.3)
Other comprehensive loss											(0.2)	(0.3)
Comprehensive loss attributable to noncontrolling interests												0.1
Comprehensive loss attributable to CyrusOne Inc.											(15.6)	(8)
Eliminations/Consolidations
Condensed Consolidating Statements of Operations
Revenue	0									0	0	0
Costs and expenses:
Property operating expenses	0									0	0	0
Sales and marketing	0									0	0	0
General and administrative	0									0	0	0
Transaction-related compensation	0
Depreciation and amortization	0									0	0	0
Restructuring charges										0
Transaction and acquisition integration costs	0									0	0	0
Asset impairments and loss on disposal										0	0
Total costs and expenses	0									0	0	0
Operating income (loss)	0									0	0	0
Interest expense	0									0	(1.7)	(2.2)
Loss on extinguishment of debt										0	0	0
Other income										0
Net loss before income taxes	0									0	1.7	2.2
Income tax expense	0									0	0	0
Equity loss related to investment in subsidiaries	18									(10.9)	2.8	(21)
Loss on sale of real estate improvements										0
Net loss	18									(10.9)	4.5	(18.8)
Noncontrolling interest in net loss										10.3	4.8	6.7
Net loss attributed to common shareholders										(0.6)	9.3	(12.1)
Other comprehensive loss											0	0
Comprehensive loss attributable to noncontrolling interests												0.1
Comprehensive loss attributable to CyrusOne Inc.											9.3	(12)
Parent Guarantor
Condensed Consolidating Statements of Operations
Revenue	0									0	0	0
Costs and expenses:
Property operating expenses	0									0	0	0
Sales and marketing	0									0	0	0
General and administrative	0									0	0	0
Transaction-related compensation	0
Depreciation and amortization	0									0	0	0
Restructuring charges										0
Transaction and acquisition integration costs	0									0	0	0
Asset impairments and loss on disposal										0	0
Total costs and expenses	0									0	0	0
Operating income (loss)	0									0	0	0
Interest expense	0									0	0	0
Loss on extinguishment of debt										0	0	0
Other income										0
Net loss before income taxes	0									0	0	0
Income tax expense	0									0	0	0
Equity loss related to investment in subsidiaries	0									(5.3)	(17.1)	(10)
Loss on sale of real estate improvements										0
Net loss	0									(5.3)	(17.1)	(10)
Noncontrolling interest in net loss										0	0	0
Net loss attributed to common shareholders										(5.3)	(17.1)	(10)
Other comprehensive loss											0	0
Comprehensive loss attributable to noncontrolling interests												0
Comprehensive loss attributable to CyrusOne Inc.											(17.1)	(10)
LP Co-issuer
Condensed Consolidating Statements of Operations
Revenue	0									0	0	0
Costs and expenses:
Property operating expenses	0									0	0	0
Sales and marketing	0									0	0	0
General and administrative	0									0	0	0
Transaction-related compensation	0
Depreciation and amortization	0									0	0	0
Restructuring charges										0
Transaction and acquisition integration costs	0									0	0	0
Asset impairments and loss on disposal										0	0
Total costs and expenses	0									0	0	0
Operating income (loss)	0									0	0	0
Interest expense	2.3									36.5	39.7	38.2
Loss on extinguishment of debt										0	0	13.6
Other income										0
Net loss before income taxes	(2.3)									(36.5)	(39.7)	(51.8)
Income tax expense	0									0	0	0
Equity loss related to investment in subsidiaries	(17.9)									20.9	17.8	35.1
Loss on sale of real estate improvements										0
Net loss	(20.2)									(15.6)	(21.9)	(16.7)
Noncontrolling interest in net loss										0	0	0
Net loss attributed to common shareholders										(15.6)	(21.9)	(16.7)
Other comprehensive loss											0	0
Comprehensive loss attributable to noncontrolling interests												0
Comprehensive loss attributable to CyrusOne Inc.											(21.9)	(16.7)
Finance Co-issuer
Condensed Consolidating Statements of Operations
Revenue	0									0	0	0
Costs and expenses:
Property operating expenses	0									0	0	0
Sales and marketing	0									0	0	0
General and administrative	0									0	0	0
Transaction-related compensation	0
Depreciation and amortization	0									0	0	0
Restructuring charges										0
Transaction and acquisition integration costs	0									0	0	0
Asset impairments and loss on disposal										0	0
Total costs and expenses	0									0	0
Operating income (loss)	0									0	0
Interest expense	0									0	0	0
Loss on extinguishment of debt										0	0	0
Other income										0
Net loss before income taxes	0									0	0
Income tax expense	0									0	0	0
Equity loss related to investment in subsidiaries	0									0	0	0
Loss on sale of real estate improvements										0
Net loss	0									0	0	0
Noncontrolling interest in net loss										0	0	0
Net loss attributed to common shareholders										0	0
Other comprehensive loss										0	0
Comprehensive loss attributable to noncontrolling interests										0
Comprehensive loss attributable to CyrusOne Inc.										0	0
Guarantor Subsidiaries
Condensed Consolidating Statements of Operations
Revenue	14.9									244.3	393.8	325.1
Costs and expenses:
Property operating expenses	4.8									85.9	146	121.9
Sales and marketing	0.7									9.7	12	12.6
General and administrative	1.4									26.3	46.6	34.2
Transaction-related compensation	20
Depreciation and amortization	5.2									87.1	138.7	115
Restructuring charges										0.7
Transaction and acquisition integration costs	0.1									1.3	14.1	1
Asset impairments and loss on disposal										2.8	13.5
Total costs and expenses	32.2									213.8	370.9	284.7
Operating income (loss)	(17.3)									30.5	22.9	40.4
Interest expense	0.1									1.8	0	0
Loss on extinguishment of debt										1.3	0	0
Other income										(0.1)
Net loss before income taxes	(17.4)									27.5	22.9	40.4
Income tax expense	(0.4)									(1.9)	(1.8)	(1.4)
Equity loss related to investment in subsidiaries	(0.1)									(4.5)	(3.3)	(3.9)
Loss on sale of real estate improvements										(0.2)
Net loss	(17.9)									20.9	17.8	35.1
Noncontrolling interest in net loss										0	0	0
Net loss attributed to common shareholders										20.9	17.8	35.1
Other comprehensive loss											0	0
Comprehensive loss attributable to noncontrolling interests												0
Comprehensive loss attributable to CyrusOne Inc.											17.8	35.1
Non- Guarantors
Condensed Consolidating Statements of Operations
Revenue	0.2									4.1	5.5	5.8
Costs and expenses:
Property operating expenses	0									2.5	2.7	2.6
Sales and marketing	0									0.2	0.1	0.2
General and administrative	0.1									0.2	0	0.4
Transaction-related compensation	0
Depreciation and amortization	0.1									2.8	2.8	3
Restructuring charges										0
Transaction and acquisition integration costs	0									0	0	0
Asset impairments and loss on disposal										0	0
Total costs and expenses	0.2									5.7	5.6	6.2
Operating income (loss)	0									(1.6)	(0.1)	(0.4)
Interest expense	0.1									2.9	3.2	3.5
Loss on extinguishment of debt										0	0	0
Other income										0
Net loss before income taxes	(0.1)									(4.5)	(3.3)	(3.9)
Income tax expense	0									0	0	0
Equity loss related to investment in subsidiaries	0									0	0	0
Loss on sale of real estate improvements										0
Net loss	(0.1)									(4.5)	(3.3)	(3.9)
Noncontrolling interest in net loss										0	0	0
Net loss attributed to common shareholders										(4.5)	(3.3)	(3.9)
Other comprehensive loss											(0.2)	(0.3)
Comprehensive loss attributable to noncontrolling interests												0
Comprehensive loss attributable to CyrusOne Inc.											(3.5)	(4.2)
General Partner
Condensed Consolidating Statements of Operations
Revenue	0									0	0	0
Costs and expenses:
Property operating expenses	0									0	0	0
Sales and marketing	0									0	0	0
General and administrative	0									0	0	0
Transaction-related compensation	0
Depreciation and amortization	0									0	0	0
Restructuring charges										0
Transaction and acquisition integration costs	0									0	0	0
Asset impairments and loss on disposal										0	0
Total costs and expenses	0									0	0	0
Operating income (loss)	0									0	0	0
Interest expense	0									0	0	0
Loss on extinguishment of debt										0	0	0
Other income										0
Net loss before income taxes	0									0	0	0
Income tax expense	0									0	0	0
Equity loss related to investment in subsidiaries	0									(0.2)	(0.2)	(0.2)
Loss on sale of real estate improvements										0
Net loss	$ 0									(0.2)	(0.2)	(0.2)
Noncontrolling interest in net loss										0	0	0
Net loss attributed to common shareholders										$ (0.2)	(0.2)	(0.2)
Other comprehensive loss											0	0
Comprehensive loss attributable to noncontrolling interests												0
Comprehensive loss attributable to CyrusOne Inc.											$ (0.2)	$ (0.2)

Guarantors - Cash Flows (Detail

Guarantors - Cash Flows (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended								11 Months Ended	12 Months Ended
	Jan. 23, 2013	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed Consolidating Statements of Cash Flows
Net loss	$ (20.2)	$ (1.2)	$ (5.3)	$ (6.5)	$ (7.2)	$ (11.8)	$ 0.2	$ (3.6)	$ 0.7	$ (15.6)	$ (20.2)	$ (14.5)
Equity loss related to investment in subsidiaries	0									0	0	0
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	5.3									89.9	141.5	118
Stock-based compensation expense										6	14.4	10.3
Non-cash interest expense										4	3.4	3.4
Provision for bad debt write off										0.4	0	0.8
Loss on extinguishment of debt										1.3	0	13.6
Asset impairments and loss on disposal										2.8	13.5	0	$ 2.8
Deferred income tax expense, including valuation allowance change										0.6
Other, net	5.9									0
Changes in operating assets and liabilities:
Rent receivables and other assets	(9.6)									(15.7)	(23.9)	(37)
Accounts payable and accrued expenses	20.5									(14.6)	7	6.9
Deferred revenues										(0.1)	5.4	9.8
Due to affiliates	1.5									18.4	(0.9)	(0.2)
Other changes in assets and liabilities	3.9
Net cash provided by operating activities	2									77.4	140.2	111.1
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate										(48)	(17.3)
Capital expenditures – other development	(7.7)									(172.9)	(217.2)	(284.2)
Business acquisition, net of cash acquired											(398.4)
Investment in and loans to subsidiaries										0	0
Changes in restricted cash	1.9									4.4	7.3	0
Intercompany advances, net	0
Return of investment										0	0	0
Intercompany contributions/distributions											0
Other										(0.2)		0
Net cash used in investing activities	(5.8)									(216.7)	(625.6)	(284.2)
Cash flows from financing activities:
Issuance of common stock										360.5	799.5	356
IPO costs										(26.6)		(1.3)
Stock issuance costs											(0.8)
Acquisition of operating partnership units											(596.4)	(355.9)
Dividends paid										(31)	(80.8)	(50.9)
Intercompany borrowings											0	0
Intercompany payments												0
Borrowings from credit facility											260	315
Payments on credit facility											(10)	(30)
Payments on senior notes											0
Proceeds from issuance of debt											103.8
Payments on capital lease obligations	(0.6)									(5.3)	(5.9)	(150.2)
Payments on lease financing arrangements										(0.7)		(3)
Payment to buyout capital leases										(9.6)		(0.9)
Payment to buyout lease financing arrangements										(10.2)		(12.8)
Payment of debt extinguishment costs											(0.8)
Contributions from/(distributions to) parent, net	0.2									0	0	0
Debt issuance costs										(1.3)	(5.4)	(5.2)
Net cash provided by (used in) by financing activities	(0.4)									275.8	463.2	60.8
Net (decrease) increase in cash and cash equivalents	(4.2)									136.5	(22.2)	(112.3)
Cash and cash equivalents at beginning of period	16.5				36.5				148.8	12.3	36.5	148.8	16.5
Cash and cash equivalents at end of period	12.3	14.3				36.5				148.8	14.3	36.5	148.8
General Partner
Condensed Consolidating Statements of Cash Flows
Net loss	0									(0.2)	(0.2)	(0.2)
Equity loss related to investment in subsidiaries	0									0.2	0.2	0.2
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	0									0	0	0
Stock-based compensation expense										0	0	0
Non-cash interest expense										0	0	0
Provision for bad debt write off										0	0	0
Loss on extinguishment of debt										0	0	0
Asset impairments and loss on disposal										0	0
Deferred income tax expense, including valuation allowance change										0
Other, net	0									0
Changes in operating assets and liabilities:
Rent receivables and other assets	0									0	0	0
Accounts payable and accrued expenses	0									0	0	0
Deferred revenues										0	0	0
Due to affiliates	0									0	0	0
Other changes in assets and liabilities	0
Net cash provided by operating activities	0									0	0	0
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate										0	0
Capital expenditures – other development	0									0	0	0
Business acquisition, net of cash acquired											0
Investment in and loans to subsidiaries										0	(2)
Changes in restricted cash	0									0	0	0
Intercompany advances, net	0
Return of investment										0	0	0
Intercompany contributions/distributions											0
Other										0		0
Net cash used in investing activities	0									0	(2)	0
Cash flows from financing activities:
Issuance of common stock										0	0	0
IPO costs										0		0
Stock issuance costs											0
Acquisition of operating partnership units											0	0
Dividends paid										0	0	0
Intercompany borrowings											0	0
Intercompany payments												0
Borrowings from credit facility											0	0
Payments on credit facility											0	0
Payments on senior notes											0
Proceeds from issuance of debt											0
Payments on capital lease obligations	0									0	0	0
Payments on lease financing arrangements										0		0
Payment to buyout capital leases										0		0
Payment to buyout lease financing arrangements										0		0
Payment of debt extinguishment costs											0
Contributions from/(distributions to) parent, net	0									0	2	0
Debt issuance costs										0	0	0
Net cash provided by (used in) by financing activities	0									0	2	0
Net (decrease) increase in cash and cash equivalents	0									0	0	0
Cash and cash equivalents at beginning of period	0				0				0	0	0	0	0
Cash and cash equivalents at end of period	0	0				0				0	0	0	0
Parent Guarantor
Condensed Consolidating Statements of Cash Flows
Net loss	0									(5.3)	(17.1)	(10)
Equity loss related to investment in subsidiaries	0									5.3	17.1	10
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	0									0	0	0
Stock-based compensation expense										0	0	0
Non-cash interest expense										0	0	0
Provision for bad debt write off										0	0	0
Loss on extinguishment of debt										0	0	0
Asset impairments and loss on disposal										0	0
Deferred income tax expense, including valuation allowance change										0
Other, net	0									(7.1)
Changes in operating assets and liabilities:
Rent receivables and other assets	0									9.4	0	0
Accounts payable and accrued expenses	0									(2.3)	0	0
Deferred revenues										0	0	0
Due to affiliates	0									0	0	0
Other changes in assets and liabilities	0
Net cash provided by operating activities	0									0	0	0
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate										0	0
Capital expenditures – other development	0									0	0	0
Business acquisition, net of cash acquired											0
Investment in and loans to subsidiaries										(337.1)	(203.1)
Changes in restricted cash	0									0	0	25.2
Intercompany advances, net	0
Return of investment										10.6	62.6	0
Intercompany contributions/distributions											0
Other										0		0
Net cash used in investing activities	0									(326.5)	(140.5)	25.2
Cash flows from financing activities:
Issuance of common stock										360.5	799.5	356
IPO costs										(23.4)		(1.3)
Stock issuance costs											(0.8)
Acquisition of operating partnership units											(596.4)	(355.9)
Dividends paid										(10.6)	(61)	(24)
Intercompany borrowings											0	0
Intercompany payments												0
Borrowings from credit facility											0	0
Payments on credit facility											0	0
Payments on senior notes											0
Proceeds from issuance of debt											0
Payments on capital lease obligations	0									0	0	0
Payments on lease financing arrangements										0		0
Payment to buyout capital leases										0		0
Payment to buyout lease financing arrangements										0		0
Payment of debt extinguishment costs											(0.8)
Contributions from/(distributions to) parent, net	0									0	0	0
Debt issuance costs										0	0	0
Net cash provided by (used in) by financing activities	0									326.5	140.5	(25.2)
Net (decrease) increase in cash and cash equivalents	0									0	0	0
Cash and cash equivalents at beginning of period	0				0				0	0	0	0	0
Cash and cash equivalents at end of period	0	0				0				0	0	0	0
LP Co-issuer
Condensed Consolidating Statements of Cash Flows
Net loss	(20.2)									(15.6)	(21.9)	(16.7)
Equity loss related to investment in subsidiaries	17.9									(20.9)	(17.8)	(35.1)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	0									0	0	0
Stock-based compensation expense										0	0	0
Non-cash interest expense										4	3.4	3.4
Provision for bad debt write off										0	0	0
Loss on extinguishment of debt										0	0	13.6
Asset impairments and loss on disposal										0	0
Deferred income tax expense, including valuation allowance change										0
Other, net	0.2									(13.4)
Changes in operating assets and liabilities:
Rent receivables and other assets	0									0	0	0.4
Accounts payable and accrued expenses	2.1									4.8	16.7	4.7
Deferred revenues										0	0	0
Due to affiliates	0									6.8	0	0
Other changes in assets and liabilities	0
Net cash provided by operating activities	0									(34.3)	(19.6)	(29.7)
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate										0	0
Capital expenditures – other development	0									0	0	0
Business acquisition, net of cash acquired											0
Investment in and loans to subsidiaries										(337.1)	(203.1)
Changes in restricted cash	0									0	0	97.3
Intercompany advances, net	0.1
Return of investment										66.5	102	180.2
Intercompany contributions/distributions											(348.4)
Other										0		(315)
Net cash used in investing activities	0.1									(270.6)	(449.5)	(37.5)
Cash flows from financing activities:
Issuance of common stock										337.1	0	0
IPO costs										0		0
Stock issuance costs											0
Acquisition of operating partnership units											0	0
Dividends paid										(31)	(80.8)	(50.9)
Intercompany borrowings											0	0
Intercompany payments												0
Borrowings from credit facility											260	315
Payments on credit facility											(10)	(30)
Payments on senior notes											0
Proceeds from issuance of debt											103.8
Payments on capital lease obligations	0									0	0	(150.2)
Payments on lease financing arrangements										0		0
Payment to buyout capital leases										0		0
Payment to buyout lease financing arrangements										0		(12.8)
Payment of debt extinguishment costs											0
Contributions from/(distributions to) parent, net	0									0	201.5	1.3
Debt issuance costs										(1.3)	(5.4)	(5.2)
Net cash provided by (used in) by financing activities	0									304.8	469.1	67.2
Net (decrease) increase in cash and cash equivalents	0.1									(0.1)	0	0
Cash and cash equivalents at beginning of period	0				0				0	0.1	0	0	0
Cash and cash equivalents at end of period	0.1	0				0				0	0	0	0
Finance Co-issuer
Condensed Consolidating Statements of Cash Flows
Net loss	0									0	0	0
Equity loss related to investment in subsidiaries	0									0	0	0
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	0									0	0	0
Stock-based compensation expense										0	0	0
Non-cash interest expense										0	0	0
Provision for bad debt write off										0	0	0
Loss on extinguishment of debt										0	0	0
Asset impairments and loss on disposal										0	0
Deferred income tax expense, including valuation allowance change										0
Other, net	0									0
Changes in operating assets and liabilities:
Rent receivables and other assets	0									0	0	0
Accounts payable and accrued expenses	0									0	0	0
Deferred revenues										0	0	0
Due to affiliates	0									0	0	0
Other changes in assets and liabilities	0
Net cash provided by operating activities	0									0	0	0
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate										0	0
Capital expenditures – other development	0									0	0	0
Business acquisition, net of cash acquired											0
Investment in and loans to subsidiaries										0	0
Changes in restricted cash	0									0	0	0
Intercompany advances, net	0
Return of investment										0	0	0
Intercompany contributions/distributions											0
Other										0		0
Net cash used in investing activities	0									0	0	0
Cash flows from financing activities:
Issuance of common stock										0	0	0
IPO costs										0		0
Stock issuance costs											0
Acquisition of operating partnership units											0	0
Dividends paid										0	0	0
Intercompany borrowings											0	0
Intercompany payments												0
Borrowings from credit facility											0	0
Payments on credit facility											0	0
Payments on senior notes											0
Proceeds from issuance of debt											0
Payments on capital lease obligations	0									0	0	0
Payments on lease financing arrangements										0		0
Payment to buyout capital leases										0		0
Payment to buyout lease financing arrangements										0		0
Payment of debt extinguishment costs											0
Contributions from/(distributions to) parent, net	0									0	0	0
Debt issuance costs										0	0	0
Net cash provided by (used in) by financing activities	0									0	0	0
Net (decrease) increase in cash and cash equivalents	0									0	0	0
Cash and cash equivalents at beginning of period	0				0				0	0	0	0	0
Cash and cash equivalents at end of period	0	0				0				0	0	0	0
Guarantor Subsidiaries
Condensed Consolidating Statements of Cash Flows
Net loss	(17.9)									20.9	17.8	35.1
Equity loss related to investment in subsidiaries	0.1									4.5	3.3	3.9
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	5.2									87.1	138.7	115
Stock-based compensation expense										6	14.4	10.3
Non-cash interest expense										0	0	0
Provision for bad debt write off										0.4	0	0.8
Loss on extinguishment of debt										1.3	0	0
Asset impairments and loss on disposal										2.8	13.5
Deferred income tax expense, including valuation allowance change										0.6
Other, net	5.6									(16.2)
Changes in operating assets and liabilities:
Rent receivables and other assets	(9.6)									(9.9)	(26.1)	(35.3)
Accounts payable and accrued expenses	18.4									0.2	(9.8)	2.1
Deferred revenues										(0.3)	5.3	10
Due to affiliates	1.5									18.4	(0.9)	(0.2)
Other changes in assets and liabilities	3.8
Net cash provided by operating activities	1.9									115.8	156.2	141.7
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate										(48)	(17.3)
Capital expenditures – other development	(7.7)									(172.9)	(216.7)	(283.9)
Business acquisition, net of cash acquired											(398.4)
Investment in and loans to subsidiaries										0	(0.4)
Changes in restricted cash	1.9									4.4	7.3	(45.4)
Intercompany advances, net	(0.1)
Return of investment										0	(17.9)	0
Intercompany contributions/distributions											0
Other										(0.2)		0
Net cash used in investing activities	(5.9)									(216.7)	(643.4)	(329.3)
Cash flows from financing activities:
Issuance of common stock										0	0	0
IPO costs										(3.2)		0
Stock issuance costs											0
Acquisition of operating partnership units											0	0
Dividends paid										(31)	(80.8)	(50.9)
Intercompany borrowings											348.4	315
Intercompany payments												(180.2)
Borrowings from credit facility											0	0
Payments on credit facility											0	0
Payments on senior notes											0
Proceeds from issuance of debt											0
Payments on capital lease obligations	(0.6)									(4.4)	(5)	0
Payments on lease financing arrangements										(0.5)		(2.4)
Payment to buyout capital leases										(9.6)		(0.7)
Payment to buyout lease financing arrangements										(10.2)		0
Payment of debt extinguishment costs											0
Contributions from/(distributions to) parent, net	0.2									295.4	201.5	(6.5)
Debt issuance costs										0	0	0
Net cash provided by (used in) by financing activities	(0.4)									236.5	464.1	74.3
Net (decrease) increase in cash and cash equivalents	(4.4)									135.6	(23.1)	(113.3)
Cash and cash equivalents at beginning of period	15.6				33.5				146.8	11.2	33.5	146.8	15.6
Cash and cash equivalents at end of period	11.2	10.4				33.5				146.8	10.4	33.5	146.8
Non- Guarantors
Condensed Consolidating Statements of Cash Flows
Net loss	(0.1)									(4.5)	(3.3)	(3.9)
Equity loss related to investment in subsidiaries	0									0	0	0
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	0.1									2.8	2.8	3
Stock-based compensation expense										0	0	0
Non-cash interest expense										0	0	0
Provision for bad debt write off										0	0	0
Loss on extinguishment of debt										0	0	0
Asset impairments and loss on disposal										0	0
Deferred income tax expense, including valuation allowance change										0
Other, net	0.1									0
Changes in operating assets and liabilities:
Rent receivables and other assets	0									(3)	2.2	(2.1)
Accounts payable and accrued expenses	0									0.3	0.1	0.1
Deferred revenues										0.2	0.1	(0.2)
Due to affiliates	0									0	0	0
Other changes in assets and liabilities	0.1
Net cash provided by operating activities	0.1									(4.2)	1.9	(3.1)
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate										0	0
Capital expenditures – other development	0									0	(0.5)	(0.3)
Business acquisition, net of cash acquired											0
Investment in and loans to subsidiaries										0	0
Changes in restricted cash	0									0	0	0
Intercompany advances, net	0
Return of investment										0	0	0
Intercompany contributions/distributions											0
Other										0		0
Net cash used in investing activities	0									0	(0.5)	(0.3)
Cash flows from financing activities:
Issuance of common stock										0	0	0
IPO costs										0		0
Stock issuance costs											0
Acquisition of operating partnership units											0	0
Dividends paid										0	0	0
Intercompany borrowings											0	0
Intercompany payments												0
Borrowings from credit facility											0	0
Payments on credit facility											0	0
Payments on senior notes											0
Proceeds from issuance of debt											0
Payments on capital lease obligations	0									(0.9)	(0.9)	0
Payments on lease financing arrangements										(0.2)		(0.6)
Payment to buyout capital leases										0		(0.2)
Payment to buyout lease financing arrangements										0		0
Payment of debt extinguishment costs											0
Contributions from/(distributions to) parent, net	0									6.3	0.4	5.2
Debt issuance costs										0	0	0
Net cash provided by (used in) by financing activities	0									5.2	(0.5)	4.4
Net (decrease) increase in cash and cash equivalents	0.1									1	0.9	1
Cash and cash equivalents at beginning of period	0.9				3				2	1	3	2	0.9
Cash and cash equivalents at end of period	1	3.9				3				2	3.9	3	2
Eliminations/Consolidations
Condensed Consolidating Statements of Cash Flows
Net loss	18									(10.9)	4.5	(18.8)
Equity loss related to investment in subsidiaries	(18)									10.9	(2.8)	21
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation and amortization	0									0	0	0
Stock-based compensation expense										0	0	0
Non-cash interest expense										0	0	0
Provision for bad debt write off										0	0	0
Loss on extinguishment of debt										0	0	0
Asset impairments and loss on disposal										0	0
Deferred income tax expense, including valuation allowance change										0
Other, net	0									36.7
Changes in operating assets and liabilities:
Rent receivables and other assets	0									(12.2)	0	0
Accounts payable and accrued expenses	0									(17.6)	0	0
Deferred revenues										0	0	0
Due to affiliates	0									(6.8)	0	0
Other changes in assets and liabilities	0
Net cash provided by operating activities	0									0.1	1.7	2.2
Cash flows from investing activities:
Capital expenditures – acquisitions of real estate										0	0
Capital expenditures – other development	0									0	0	0
Business acquisition, net of cash acquired											0
Investment in and loans to subsidiaries										674.2	408.6
Changes in restricted cash	0									0	0	(77.1)
Intercompany advances, net	0
Return of investment										(77.1)	(146.7)	(180.2)
Intercompany contributions/distributions											348.4
Other										0		315
Net cash used in investing activities	0									597.1	610.3	57.7
Cash flows from financing activities:
Issuance of common stock										(337.1)	0	0
IPO costs										0		0
Stock issuance costs											0
Acquisition of operating partnership units											0	0
Dividends paid										41.6	141.8	74.9
Intercompany borrowings											(348.4)	(315)
Intercompany payments												180.2
Borrowings from credit facility											0	0
Payments on credit facility											0	0
Payments on senior notes											0
Proceeds from issuance of debt											0
Payments on capital lease obligations	0									0	0	0
Payments on lease financing arrangements										0		0
Payment to buyout capital leases										0		0
Payment to buyout lease financing arrangements										0		0
Payment of debt extinguishment costs											0
Contributions from/(distributions to) parent, net	0									(301.7)	(405.4)	0
Debt issuance costs										0	0	0
Net cash provided by (used in) by financing activities	0									(597.2)	(612)	(59.9)
Net (decrease) increase in cash and cash equivalents	0									0	0	0
Cash and cash equivalents at beginning of period	0				$ 0				$ 0	0	0	0	0
Cash and cash equivalents at end of period	$ 0	$ 0				$ 0				$ 0	$ 0	$ 0	$ 0

Quarterly Financial Informati90

Quarterly Financial Information (Unaudited) - Schedule of Quarterly Information (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	1 Months Ended				3 Months Ended								11 Months Ended	12 Months Ended
	Jun. 30, 2015	Apr. 30, 2015	Jun. 30, 2014	Jan. 23, 2013	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Class of Stock [Line Items]
Revenue				$ 15.1	$ 113.3	$ 111.2	$ 89.1	$ 85.7	$ 86.9	$ 84.8	$ 81.7	$ 77.5	$ 248.4	$ 399.3	$ 330.9
Operating income (loss)				(17.3)	11.1	7.5	2.6	1.6	11.2	9.6	7.4	11.8	28.9	22.8	40
Net loss				$ (20.2)	(1.2)	(5.3)	(6.5)	(7.2)	(11.8)	0.2	(3.6)	0.7	(15.6)	(20.2)	(14.5)
Net loss attributed to common shareholders					$ (1)	$ (4.6)	$ (5.5)	$ (4.3)	$ (7)	$ 0.1	$ (1.1)	$ 0.2	$ (5.3)	$ (15.4)	$ (7.8)	$ (5.3)
Loss per share, including anti-dilutive securities - basic and diluted (in dollars per share)					$ (0.02)	$ (0.08)	$ (0.11)	$ (0.12)	$ (0.19)	$ 0	$ (0.06)	$ 0		$ (0.33)	$ (0.25)
Loss per share - basic and diluted (in dollars per share)														$ (0.30)	$ (0.30)
IPO
Class of Stock [Line Items]
Anti-dilutive securities excluded from diluted earning per share (in shares)	6	14.3	16

Valuation and Qualifying Acco91

Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	$ 1	$ 0.5	$ 0.3
Charge to Expenses	0	0.8	0.4
Deductions/(Additions)	0	0.3	0.2
Beginning of Period	1	1	0.5
Deferred Tax Valuation Allowance
Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning of Period	5.7	3.6	1.9
Charge to Expenses	0.6	2.1	1.7
Deductions/(Additions)	0	0	0
Beginning of Period	$ 6.3	$ 5.7	$ 3.6

Real Estate Properties and Ac92

Real Estate Properties and Accumulated Depreciation - Schedule of Real Estate Properties (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Initial Costs
Land	$ 92.4
Building and Improvements	312.6
Equipment	103.3
Cost Capitalized Subsequent to Acquisition
Land	0.6
Building and Improvements	592.7
Equipment	494.9
Gross Carrying Amount
Land	93	$ 89.7
Building and Improvements	905.3	812.6
Equipment	598.2	349.1
Accumulated Depreciation	435.6	327	$ 236.7	$ 176.7
Aggregate cost of the total properties for federal income tax purposes	2,419.1
West Seventh St., Cincinnati, OH (7th Street)
Initial Costs
Land	0.9
Building and Improvements	42.2
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	68.4
Equipment	19.6
Gross Carrying Amount
Land	0.9	0.9
Building and Improvements	110.6	110.6
Equipment	19.6	12.7
Accumulated Depreciation	75.1
Parkway Dr., Mason, OH (Mason)
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	20.2
Equipment	1
Gross Carrying Amount
Land	0	0
Building and Improvements	20.2	20.2
Equipment	1	0.9
Accumulated Depreciation	11.8
Industrial Rd., Florence, KY (Florence)
Initial Costs
Land	2.2
Building and Improvements	7.7
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	33.8
Equipment	3.3
Gross Carrying Amount
Land	2.2	2.2
Building and Improvements	41.5	41.4
Equipment	3.3	3
Accumulated Depreciation	21.8
Goldcoast Dr., Cincinnati, OH (Goldcoast)
Initial Costs
Land	0.6
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	6.7
Equipment	0.1
Gross Carrying Amount
Land	0.6	0.6
Building and Improvements	6.7	6.7
Equipment	0.1	0.1
Accumulated Depreciation	2.6
Knightsbridge Dr., Hamilton, OH (Hamilton)
Initial Costs
Land	0
Building and Improvements	9.5
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	39.7
Equipment	4.4
Gross Carrying Amount
Land	0	0
Building and Improvements	49.2	49.2
Equipment	4.4	3.7
Accumulated Depreciation	22.7
E. Monroe St., South Bend, IN (Monroe St.)
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	2.5
Equipment	0.3
Gross Carrying Amount
Land	0	0
Building and Improvements	2.5	2.5
Equipment	0.3	0.1
Accumulated Depreciation	1.3
Springer St., Lombard, IL (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	7.6
Gross Carrying Amount
Land	0.7	0.7
Building and Improvements	4.7	4.7
Equipment	7.6	5.7
Accumulated Depreciation	2.9
Crescent Circle, South Bend, IN (Blackthorn)
Initial Costs
Land	0
Building and Improvements	1.1
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	2.2
Equipment	0.4
Gross Carrying Amount
Land	0	0
Building and Improvements	3.3	3.3
Equipment	0.4	0.1
Accumulated Depreciation	1.5
Kingsview Dr., Lebanon, OH (Lebanon)
Initial Costs
Land	4
Building and Improvements	12.3
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	65
Equipment	7.6
Gross Carrying Amount
Land	4	4
Building and Improvements	77.3	77
Equipment	7.6	5.5
Accumulated Depreciation	26.5
McAuley Place, Blue Ash, OH (Blue Ash)
Initial Costs
Land	0
Building and Improvements	2.6
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	(2)
Equipment	0.1
Gross Carrying Amount
Land	0	0
Building and Improvements	0.6	0.6
Equipment	0.1	0.1
Accumulated Depreciation	0.3
Westway Park Blvd., Houston, TX (Houston West 1)
Initial Costs
Land	1.4
Building and Improvements	21.4
Equipment	0.1
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	63.4
Equipment	46.3
Gross Carrying Amount
Land	1.4	1.4
Building and Improvements	84.8	84.4
Equipment	46.4	43.8
Accumulated Depreciation	51.7
Westway Park Blvd., Houston, TX (Houston West 2)
Initial Costs
Land	2
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	22.6
Equipment	47.1
Gross Carrying Amount
Land	2	2
Building and Improvements	22.6	22.5
Equipment	47.1	45.1
Accumulated Depreciation	15.3
Westway Park Blvd., Houston, TX (Houston West 3)
Initial Costs
Land	18.3
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0.1
Building and Improvements	4
Equipment	0.8
Gross Carrying Amount
Land	18.4	18.4
Building and Improvements	4	0
Equipment	0.8	0
Accumulated Depreciation	0.3
Southwest Fwy., Houston, TX (Galleria)
Initial Costs
Land	0
Building and Improvements	56
Equipment	2
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	12.6
Equipment	14
Gross Carrying Amount
Land	0	0
Building and Improvements	68.6	68.6
Equipment	16	15
Accumulated Depreciation	36.8
E. Ben White Blvd., Austin, TX (Austin 1)
Initial Costs
Land	0
Building and Improvements	11.9
Equipment	0.2
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	1.7
Equipment	0.8
Gross Carrying Amount
Land	0	0
Building and Improvements	13.6	22.5
Equipment	1	1.2
Accumulated Depreciation	10.1
S. State Highway 121 Business, Lewisville, TX (Lewisville)
Initial Costs
Land	0
Building and Improvements	46.2
Equipment	2.2
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	30.4
Equipment	22.7
Gross Carrying Amount
Land	0	0
Building and Improvements	76.6	76.7
Equipment	24.9	22.8
Accumulated Depreciation	45.3
Marsh Lane, Carrollton, TX (Marsh Ln)
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0.1
Equipment	0.6
Gross Carrying Amount
Land	0	0
Building and Improvements	0.1	0.1
Equipment	0.6	0.5
Accumulated Depreciation	0.4
Midway Rd., Carrollton, TX (Midway)
Initial Costs
Land	0
Building and Improvements	1.8
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0.2
Equipment	0.4
Gross Carrying Amount
Land	0	0
Building and Improvements	2	2
Equipment	0.4	0.4
Accumulated Depreciation	2.2
W. Frankford Rd., Carrollton, TX (Carrollton)
Initial Costs
Land	16.1
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	52.7
Equipment	116.5
Gross Carrying Amount
Land	16.1	16.1
Building and Improvements	52.7	51.6
Equipment	116.5	85.3
Accumulated Depreciation	34.3
Bryan St., Dallas, TX (Bryan St)
Initial Costs
Land	0
Building and Improvements	0.1
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	(0.1)
Equipment	0
Gross Carrying Amount
Land	0	0
Building and Improvements	0	0.1
Equipment	0	0.2
Accumulated Depreciation	0
North Freeway, Houston, TX (Greenspoint)
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0
Equipment	0
Gross Carrying Amount
Land	0	0
Building and Improvements	0	1.3
Equipment	0	0
Accumulated Depreciation	0
South Ellis Street, Chandler, AZ (Phoenix 1)
Initial Costs
Land	14.8
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	56.7
Equipment	39.8
Gross Carrying Amount
Land	14.8	14.8
Building and Improvements	56.7	56.4
Equipment	39.8	43.9
Accumulated Depreciation	18.5
South Ellis Street, Chandler, AZ (Phoenix 2)
Initial Costs
Land	0
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	16
Equipment	39.5
Gross Carrying Amount
Land	0	0
Building and Improvements	16	13.2
Equipment	39.5	21.8
Accumulated Depreciation	5.3
Westover Hills Blvd., San Antonio, TX (San Antonio 1)
Initial Costs
Land	4.6
Building and Improvements	3
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	29.1
Equipment	33
Gross Carrying Amount
Land	4.6	4.6
Building and Improvements	32.1	32.1
Equipment	33	32.4
Accumulated Depreciation	15.9
Westover Hills Blvd., San Antonio, TX (San Antonio 2)
Initial Costs
Land	6.7
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0.3
Building and Improvements	0
Equipment	0.1
Gross Carrying Amount
Land	7	7
Building and Improvements	0	0
Equipment	0.1	0
Accumulated Depreciation	0
Metropolis Dr., Austin, TX (Austin 2)
Initial Costs
Land	2
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	23.2
Equipment	5.7
Gross Carrying Amount
Land	2	2
Building and Improvements	23.2	23.2
Equipment	5.7	4
Accumulated Depreciation	9.6
Myer Conners Rd (Wappinger Falls)
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	1.1
Gross Carrying Amount
Land	0	0
Building and Improvements	11.3	0
Equipment	14.4	0
Accumulated Depreciation	1.3
Madison Road (Totowa)
Initial Costs
Land	0
Building and Improvements	28.3
Equipment	45.6
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0
Equipment	3.2
Gross Carrying Amount
Land	0	0
Building and Improvements	28.3	0
Equipment	48.8	0
Accumulated Depreciation	3.8
Commerce Road (Totowa)
Initial Costs
Land	0
Building and Improvements	4.1
Equipment	0.8
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0
Equipment	0.2
Gross Carrying Amount
Land	0	0
Building and Improvements	4.1	0
Equipment	1	0
Accumulated Depreciation	0.2
Norden Place (Norwalk)
Initial Costs
Land	0
Building and Improvements	18.3
Equipment	25.3
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0
Equipment	0.1
Gross Carrying Amount
Land	0	0
Building and Improvements	18.3	0
Equipment	25.4	0
Accumulated Depreciation	1.6
Riverbend Drive South (Stamford)
Initial Costs
Land	0
Building and Improvements	4.3
Equipment	13.2
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0
Equipment	0
Gross Carrying Amount
Land	0	0
Building and Improvements	4.3	0
Equipment	13.2	0
Accumulated Depreciation	1.2
Omega Drive (Stamford)
Initial Costs
Land	0
Building and Improvements	3.2
Equipment	0.6
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	0
Equipment	0.9
Gross Carrying Amount
Land	0	0
Building and Improvements	3.2	0
Equipment	1.5	0
Accumulated Depreciation	0.2
Kestral Way (London)
Initial Costs
Land	0
Building and Improvements	16.5
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	14.7
Equipment	0.8
Gross Carrying Amount
Land	0	0
Building and Improvements	31.2	32.7
Equipment	0.8	0.7
Accumulated Depreciation	6
Jurong East (Singapore)
Initial Costs
Land	0
Building and Improvements	9
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	(0.6)
Equipment	0.1
Gross Carrying Amount
Land	0	0
Building and Improvements	8.4	9
Equipment	0.1	0.1
Accumulated Depreciation	3.6
Ridgetop Circle, Sterling, VA (Northern Virginia)
Initial Costs
Land	6.9
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0.1
Building and Improvements	19.2
Equipment	45.2
Gross Carrying Amount
Land	7	7
Building and Improvements	19.2	0
Equipment	45.2	0
Accumulated Depreciation	5
Metropolis Dr., Austin, TX (Austin 3)
Initial Costs
Land	7.9
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0.1
Building and Improvements	0
Equipment	0.1
Gross Carrying Amount
Land	8	8
Building and Improvements	0	0
Equipment	0.1	0
Accumulated Depreciation	0
Metropolis Dr., Austin, TX (Austin 4)
Initial Costs
Land	3.3
Building and Improvements	0
Equipment	0
Cost Capitalized Subsequent to Acquisition
Land	0
Building and Improvements	7.4
Equipment	31.5
Gross Carrying Amount
Land	3.3	0
Building and Improvements	7.4	0
Equipment	31.5	$ 0
Accumulated Depreciation	$ 0.5

Real Estate Properties and Ac93

Real Estate Properties and Accumulated Depreciation - Historical Cost and Accumulated Depreciation and Amortization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property
Balance—beginning of period	$ 1,378.4	$ 1,120.5	$ 883.6
Disposals	(7)	(0.1)	(8.5)
Impairments	(9.3)	0	(4)
Additions (acquisitions and improvements)	465.5	258	249.4
Balance, end of period	1,827.6	1,378.4	1,120.5
Accumulated Depreciation
Balance—beginning of period	327	236.7	176.7
Disposals	(2.7)	0	(9.3)
Impairments	0	0	(0.9)
Additions (depreciation and amortization expense)	111.3	90.3	70.2
Balance, end of period	$ 435.6	$ 327	$ 236.7

Uncategorized Items - cone-2015

Label	Element	Value
Stock Issued During Period, Value, Restricted Stock Award, Gross	us-gaap_StockIssuedDuringPeriodValueRestrictedStockAwardGross	$ 0
Stock Issued During Period Value In Settlement Of Issuing Cost With Parent Entity	cone_StockIssuedDuringPeriodValueInSettlementOfIssuingCostWithParentEntity	0
Stock Issued During Period, Value, New Issues	us-gaap_StockIssuedDuringPeriodValueNewIssues	337,100,000
Noncontrolling Interest, Increase from Business Combination	us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination	0
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	6,200,000
Contributions From Parent	cone_ContributionsFromParent	19,600,000
Other Contribution From Parent	cone_OtherContributionFromParent	1,300,000
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts	9,500,000
Additional Paid-in Capital [Member]
Stock Issued During Period Value In Settlement Of Issuing Cost With Parent Entity	cone_StockIssuedDuringPeriodValueInSettlementOfIssuingCostWithParentEntity	7,100,000
Stock Issued During Period, Value, New Issues	us-gaap_StockIssuedDuringPeriodValueNewIssues	336,900,000
Noncontrolling Interest, Increase from Business Combination	us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination	(7,100,000)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	6,200,000
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts	$ 9,500,000
Common Stock [Member]
Stock Issued During Period, Shares, Restricted Stock Award, Gross	us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardGross	1,100,000
Stock Issued During Period Share In Settlement Of Issuing Cost With Parent Entity	cone_StockIssuedDuringPeriodShareInSettlementOfIssuingCostWithParentEntity	400,000
Stock Issued During Period, Value, New Issues	us-gaap_StockIssuedDuringPeriodValueNewIssues	$ 200,000
Stock Issued During Period Share To Parent Entity In Exchange Of Equity Interest In Third Entity	cone_StockIssuedDuringPeriodShareToParentEntityInExchangeOfEquityInterestInThirdEntity	1,500,000
Stock Issued During Period, Shares, New Issues	us-gaap_StockIssuedDuringPeriodSharesNewIssues	19,000,000
Noncontrolling Interest [Member]
Stock Issued During Period Value In Settlement Of Issuing Cost With Parent Entity	cone_StockIssuedDuringPeriodValueInSettlementOfIssuingCostWithParentEntity	$ (7,100,000)
Noncontrolling Interest, Increase from Business Combination	us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination	500,800,000
Parent [Member]
Stock Issued During Period Value In Settlement Of Issuing Cost With Parent Entity	cone_StockIssuedDuringPeriodValueInSettlementOfIssuingCostWithParentEntity	7,100,000
Stock Issued During Period, Value, New Issues	us-gaap_StockIssuedDuringPeriodValueNewIssues	337,100,000
Noncontrolling Interest, Increase from Business Combination	us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination	(500,800,000)
Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition	us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	6,200,000
Contributions From Parent	cone_ContributionsFromParent	19,600,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	(20,200,000)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	(15,600,000)
Other Contribution From Parent	cone_OtherContributionFromParent	1,300,000
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs	us-gaap_AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts	9,500,000
Partnership Interest [Member]
Noncontrolling Interest, Increase from Business Combination	us-gaap_NoncontrollingInterestIncreaseFromBusinessCombination	(493,700,000)
Contributions From Parent	cone_ContributionsFromParent	19,600,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	(20,200,000)
Other Contribution From Parent	cone_OtherContributionFromParent	1,300,000
Retained Earnings [Member]
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	13,600,000
Net Income (Loss) Attributable to Noncontrolling Interest	us-gaap_NetIncomeLossAttributableToNoncontrollingInterest	10,300,000
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	us-gaap_ProfitLoss	$ (15,600,000)