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The maximum additional number of shares that could be issued to net share settle a contract, if applicable.

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Percentage of leases on total assets

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For unclassified balance sheet, amounts due from customers or clients for goods or services that have been delivered or sold in the normal course of business.

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The amount of cash as of the balance sheet date that is not insured by the Federal Deposit Insurance Corporation.

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The cumulative difference between the rental payments required by a lease agreement and the rental income or expense recognized on a straight-line basis, or other systematic and rational basis more representative of the time pattern in which use or benefit is granted or derived from the leased property, expected to be recognized in income or expense over the term of the leased property, by the lessor or lessee, respectively. Such receivable is reduced by allowances attributable to, for instance, credit risk associated with a lessee.

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The per share price of the Company's stock at which the contract holder of the freestanding contract has the right to purchase or sell the Company's stock at a future date.

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Settlement date of the forward contract indexed to issuer's equity, in CCYY-MM-DD format.

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The maximum number of shares that could be issued to net share settle a contract, if applicable. If a contract does not have a fixed or determinable maximum number of shares that may be required to be issued, disclose the fact that a potentially infinite number of shares could be issued to settle the contract.

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Additional shared included in the calculation of diluted EPS as a result of the potentially dilutive effect of equity forward arrangements using the reverse treasury stock method.

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Percentage investment held by the managing member or general partner of the limited liability company (LLC) or limited partnership (LP).

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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

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Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

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Summary of Significant Accounting Policies (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended		12 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Line Items]
Number of Reportable Segments			1
Cash in Excess of FDIC Insured Amounts			$ 52,700	$ 57,500
Deferred Rent Receivables, Net			$ 16,700	12,900
Incremental Common Shares Attributable to Dilutive Effect of Equity Forward Agreements			261,731
Proceeds From Issuance Of Common Stock			$ 339,744	222,695	$ 228,011
Percentage Of Leases On Total Assets			1.00%
March 2018 Forward Sale [Member]
Accounting Policies [Line Items]
Forward Contract Indexed to Issuer's Equity, Shares		3,450,000
Forward Contract Indexed to Issuer's Equity, Additional Shares		450,000
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share		$ 48.00
Forward Contract Indexed to Issuer's Equity, Settlement Date	Sep. 30, 2018
Incremental Common Shares Attributable to Dilutive Effect of Equity Forward Agreements			198,786
Proceeds From Issuance Of Common Stock	$ 160,200
September 2018 Forward Sales [Member]
Accounting Policies [Line Items]
Forward Contract Indexed to Issuer's Equity, Shares	3,500,000
Forward Contract Indexed to Issuer's Equity, Forward Rate Per Share	$ 55.20
Forward Contract Indexed to Issuer's Equity, Settlement Date	Sep. 03, 2019
Incremental Common Shares Attributable to Dilutive Effect of Equity Forward Agreements			62,945
Unbilled Revenues [Member]
Accounting Policies [Line Items]
Accounts Receivable, Gross			$ 3,300	$ 1,400
Maximum [Member] \| September 2018 Forward Sales [Member]
Accounting Policies [Line Items]
Forward Contract Indexed to Issuer's Equity, Settlement Date	Sep. 03, 2019
Building [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			40 years
Building Improvements [Member] \| Minimum [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			10 years
Building Improvements [Member] \| Maximum [Member]
Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life			20 years
General Partner [Member]
Accounting Policies [Line Items]
Percentage of Operating Partnership Owned			99.10%	98.80%