Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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- Definition

Fair value of the assets less the liabilities of a derivative or group of derivatives.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
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- Definition

Fixed interest rate related to the interest rate derivative.

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- Definition

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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- Definition

Date the derivative contract matures, in CCYY-MM-DD format.

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- Definition

Amount after tax of reclassification adjustment from accumulated other comprehensive income of accumulated gain (loss) realized from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's deferred hedging gain (loss).

+ References

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-Topic 815
-SubTopic 10
-Section 50
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Interest Rate Swaps - Interest rate derivatives and their fair values (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2019	Dec. 31, 2017	Apr. 05, 2017
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Reclassification of other comprehensive income to interest expense	$ (83)	$ 410
Forecast
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Reclassification of other comprehensive income to interest expense			$ (2,400)
Interest Rate Swap
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative					$ 400,000
Interest Rate Swap \| Cash flow hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	400,000	400,000		$ 400,000
Fair value	11,422	11,422		1,449
Swap instrument one matures on December 17, 2021 \| Cash flow hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	$ 25,000	$ 25,000		$ 25,000
Fixed Rate Per annum	1.989%	1.989%		1.989%
Expiration Date		Dec. 17, 2021		Dec. 17, 2021
Fair value	$ 692	$ 692		$ 100
Swap instrument two matures on December 17, 2021 \| Cash flow hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	$ 100,000	$ 100,000		$ 100,000
Fixed Rate Per annum	1.989%	1.989%		1.989%
Expiration Date		Dec. 17, 2021		Dec. 17, 2021
Fair value	$ 2,765	$ 2,765		$ 401
Swap instrument three matures on December 17, 2021 \| Cash flow hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	$ 75,000	$ 75,000		$ 75,000
Fixed Rate Per annum	1.989%	1.989%		1.989%
Expiration Date		Dec. 17, 2021		Dec. 17, 2021
Fair value	$ 2,072	$ 2,072		$ 298
Swap instrument one matures on April 27, 2022 \| Cash flow hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	$ 50,000	$ 50,000		$ 50,000
Fixed Rate Per annum	2.033%	2.033%		2.033%
Expiration Date		Apr. 27, 2022		Apr. 27, 2022
Fair value	$ 1,472	$ 1,472		$ 158
Swap instrument two matures on April 27, 2022 \| Cash flow hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	$ 100,000	$ 100,000		$ 100,000
Fixed Rate Per annum	2.029%	2.029%		2.029%
Expiration Date		Apr. 27, 2022		Apr. 27, 2022
Fair value	$ 2,955	$ 2,955		$ 337
Swap instrument three matures on April 27, 2022 \| Cash flow hedging
Derivative Instruments and Hedging Activities Disclosures [Line Items]
Notional amount of derivative	$ 50,000	$ 50,000		$ 50,000
Fixed Rate Per annum	2.033%	2.033%		2.033%
Expiration Date		Apr. 27, 2022		Apr. 27, 2022
Fair value	$ 1,466	$ 1,466		$ 155