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

The estimated net amount of existing gains or losses on cash flow hedges at the reporting date expected to be reclassified to earnings within the next 12 months.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994

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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.

+ References

No definition available.

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- Definition

Amount of unrealized gain (loss) related to derivatives designated as cash flow hedging instruments, recorded in results of operations to the extent that the cash flow hedge is determined to be ineffective.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (d)(1)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624171-113959

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Derivative Instruments And Hedging Activities - Narrative (Details) NOK in Millions, $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2015 NOK	Jun. 30, 2015 USD ($)	Feb. 28, 2013 USD ($)	Feb. 28, 2013 NOK	Jan. 31, 2013 USD ($)	Jan. 31, 2013 NOK
Derivative [Line Items]
Losses in Accumulated OCI to be re-classified within twelve months	$ 4.6
Other Income (Expense), Net [Member]
Derivative [Line Items]
Unrealized losses on hedge ineffectiveness		$ (0.1)
Interest Rate Swaps [Member] \| Nordea Q5000 Loan Maturing April 2020 [Member]
Derivative [Line Items]
Notional amount				$ 187.5
Grand Canyon [Member]
Derivative [Line Items]
Notional amount							$ 104.6	NOK 591.3
Grand Canyon II [Member]
Derivative [Line Items]
Notional amount			NOK 434.1		$ 100.4	NOK 594.7
Grand Canyon III [Member]
Derivative [Line Items]
Notional amount			NOK 185.2		$ 98.8	NOK 595.0