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Debt Instrument Percentage Of Principal Amount To Be Remained Outstanding Before Specified Date Five

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Debt Instrument Redemption Price As Percentage Of Principal Amount Beginning Specified Date One

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Debt Instrument Redemption Price As Percentage Of Principal Amount Beginning Specified Date Two

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Minimum Unencumbered Asset Value Percentage Of Unsecured Debt

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Term of Debt Instrument Extension Option

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Amount of amortization expense attributable to debt issuance costs.

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Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Fair value amount of debt instrument that was repurchased.

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Face (par) amount of the original debt instrument that was repurchased.

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Amount, after accumulated amortization, of debt premium.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Amount of gain (loss) from the difference between the repurchase price of a debt instrument initially issued by the entity and the net carrying amount of the debt at the time of its repurchase.

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The amount, during the lease term, of each minimum [capital] lease payment allocated to interest expense so as to produce a constant periodic rate of interest on the remaining balance of the capital lease obligation.

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Amount of the fee for available but unused credit capacity under the credit facility.

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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Long-Term Debt, Capital Lease Obligations and Lease Financing Arrangements - Narrative (Details)			1 Months Ended	2 Months Ended	3 Months Ended		9 Months Ended
	Jul. 01, 2015 USD ($)	Nov. 20, 2012 USD ($)	Jul. 31, 2016 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) data_center	Sep. 30, 2015 USD ($)	Mar. 17, 2016 USD ($)	Dec. 31, 2015 USD ($)
Debt Instrument [Line Items]
Deferred financing costs					$ 16,700,000		$ 16,700,000			$ 17,600,000
Long-term debt, net					1,065,700,000		$ 1,065,700,000			$ 996,500,000
Total unencumbered assets							150.00%
Repayments of notes payable			$ 1,400,000				$ 1,500,000	$ 0
Amortization of deferred financing costs					1,000,000	$ 1,000,000	$ 3,000,000	2,400,000
Number of data center facilities under capital leases \| data_center							8
Interest expense on capital lease obligations					3,400,000	2,500,000	$ 8,300,000	5,200,000
First Amendment to Credit Agreement \| Term Loan
Debt Instrument [Line Items]
Credit agreement amount					$ 300,000,000.0		$ 300,000,000.0
Second Amendment to Credit Agreement \| Term Loan
Debt Instrument [Line Items]
Optional additional borrowing capacity									$ 250,000,000
Second Amendment to Credit Agreement \| Term Loan \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate							1.65%
6.375% senior notes due 2022, including bond premium
Debt Instrument [Line Items]
Stated interest rate		6.375%			6.375%		6.375%			6.375%
6.375% senior notes due 2022, including bond premium \| Senior Notes
Debt Instrument [Line Items]
Long-term debt, net					$ 477,400,000		$ 477,400,000			$ 477,600,000
Stated interest rate					6.375%		6.375%			6.375%
Repurchased face amount				$ 150,200,000
Repurchased amount				163,000,000
Loss on extinguishment of debt				$ 12,800,000
Proceeds from issuance of private offering	$ 100,000,000.0
Premium on debt	$ 3,800,000
6.375% senior notes due 2022, including bond premium \| Senior Notes \| Cyrus One Lp And Cyrus One Finance Corp
Debt Instrument [Line Items]
Long-term debt, net		$ 525,000,000
Stated interest rate		6.375%			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
Revolving credit facility
Debt Instrument [Line Items]
Commitment fee percent							0.25%
Commitment fee amount					$ 400,000	$ 300,000	$ 1,100,000	$ 600,000
Maximum percentage of dividends allowed to be distributed					95.00%		95.00%
Revolving credit facility \| Term Loan
Debt Instrument [Line Items]
Deferred financing costs					$ 2,100,000		$ 2,100,000
Revolving credit facility \| First Amendment to Credit Agreement
Debt Instrument [Line Items]
Credit agreement amount					$ 650,000,000.0		$ 650,000,000.0
Revolving credit facility \| Second Amendment to Credit Agreement
Debt Instrument [Line Items]
Optional additional borrowing capacity									$ 250,000,000
Term of extension option							1 year
Revolving credit facility \| Second Amendment to Credit Agreement \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate							1.70%