Summary of Significant Accounting Policies (Additional Information 2) (Details) - segment	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments	1
Number of reportable segments	1
Effective tax rate	(8.50%)	8.90%
Lease, Practical Expedients, Package [true/false]	true
Lease, Practical Expedient, Use of Hindsight [true/false]	false
Customer One \| Rental Revenue
Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenue	9.80%
Three Customers [Member] \| Accounts Receivable \| Trade Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Percentage of trade accounts receivable	26.00%
Three Customers [Member] \| Accounts Receivable \| Minimum \| Trade Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Percentage of trade accounts receivable	5.00%
One of Three Customers [Member] \| Accounts Receivable \| Minimum \| Trade Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Percentage of trade accounts receivable	10.00%
One of Three Customers [Member] \| Accounts Receivable \| Maximum \| Trade Accounts Receivable
Summary Of Significant Accounting Policies [Line Items]
Percentage of trade accounts receivable	13.00%
No Other Customers \| Rental Revenue \| Minimum
Summary Of Significant Accounting Policies [Line Items]
Percentage of total revenue	6.00%

Percentage of total accounts receivable.

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Summary Of Significant Accounting Policies [Line Items]

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Indicates (true false) whether practical expedient is elected to use hindsight in determining lease term and in assessing impairment of right-of-use asset.

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Indicates (true false) whether practical expedients are elected for not reassessing whether any expired or existing contract is or contains lease, lease classification for expired or existing lease, and initial direct cost for any existing lease.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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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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