Debt (Outstanding Debt Including Capital Leases) (Details) - USD ($) $ in Thousands	9 Months Ended
Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Weighted average coupon interest rate	3.97%
Capital Lease and Lease Financing Obligations	$ 4,000
Total debt and lease obligations	1,187,180	$ 1,241,565
Less discount and net debt issuance costs	10,353	11,636
Total outstanding debt, net	$ 1,176,827	1,229,929
Revolving Credit Facility
Debt Instrument [Line Items]
Weighted average coupon interest rate	3.70%
Maturity date	Dec. 17, 2021
Outstanding debt	$ 81,000	131,000
Term Loan I [Member]
Debt Instrument [Line Items]
Weighted average coupon interest rate	3.54%
Maturity date	Dec. 17, 2022
Outstanding debt	$ 350,000	350,000
Term Loan II [Member]
Debt Instrument [Line Items]
Weighted average coupon interest rate	3.56%
Maturity date	Apr. 27, 2023
Outstanding debt	$ 350,000	350,000
Lenexa Mortgage
Debt Instrument [Line Items]
Weighted average coupon interest rate	4.10%
Maturity date	May 01, 2022
Outstanding debt	$ 1,823	1,866
Capital Lease and Lease Financing Obligations [Member]
Debt Instrument [Line Items]
Weighted average coupon interest rate	3.53%
Maturity date description	2018 - 2038
Capital Lease and Lease Financing Obligations	$ 4,357	8,699
Operating Partnership Quality Tech LP And QTS Finance Corporation
Debt Instrument [Line Items]
Weighted average coupon interest rate	4.75%
Maturity date	Nov. 15, 2025
Outstanding debt	$ 400,000	$ 400,000

Amount equal to the present value (the principal) at the beginning of the lease term of minimum lease payments during the lease term (excluding that portion of the payments representing executory costs such as insurance, maintenance, and taxes to be paid by the lessor, together with any profit thereon) net of payments or other amounts applied to the principal through the balance sheet date.

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Sum of the carrying values as of the balance sheet date of all debt, including all short-term borrowings, long-term debt, and capital lease obligations.

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Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

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Amount, after accumulated amortization, of debt discount (premium).

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Weighted average interest rate of debt outstanding.

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