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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- References

No definition available.

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- Definition

The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

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- Definition

Fair value as of the balance sheet date of all foreign currency derivatives designated as cash flow hedging instruments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(b),(c)(1)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

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Risk Management and Use of Derivative Financial Instruments - Foreign Currency Derivatives Details (Details) € in Thousands, kr in Thousands, $ in Thousands	Jun. 30, 2018 USD ($) instrument	Jun. 30, 2018 NOK (kr) instrument	Jun. 30, 2018 EUR (€) instrument
Derivative Instrument Detail
Fair value, foreign currency derivatives	$ 13,653
Derivatives Designated as Hedging Instruments \| Cash Flow Hedging \| Foreign currency forward contracts \| Euro
Derivative Instrument Detail
Number of Instruments \| instrument	27	27	27
Notional Amount \| €			€ 68,286
Fair value, foreign currency derivatives	$ 14,073
Derivatives Designated as Hedging Instruments \| Cash Flow Hedging \| Foreign currency collars \| Euro
Derivative Instrument Detail
Number of Instruments \| instrument	2	2	2
Notional Amount \| €			€ 15,100
Fair value, foreign currency derivatives	$ (919)
Derivatives Designated as Hedging Instruments \| Cash Flow Hedging \| Foreign currency collars \| NOK
Derivative Instrument Detail
Number of Instruments \| instrument	3	3	3
Notional Amount \| kr		kr 2,000
Fair value, foreign currency derivatives	$ (17)
Derivatives Designated as Hedging Instruments \| Designated as Net Investment Hedging Instruments \| Foreign currency forward contracts \| NOK
Derivative Instrument Detail
Number of Instruments \| instrument	2	2	2
Notional Amount \| kr		kr 4,329
Fair value, foreign currency derivatives	$ 57
Derivatives Designated as Hedging Instruments \| Designated as Net Investment Hedging Instruments \| Foreign currency collars \| NOK
Derivative Instrument Detail
Number of Instruments \| instrument	1	1	1
Notional Amount \| kr		kr 2,500
Fair value, foreign currency derivatives	$ (21)
Not Designated as Hedging Instrument \| Foreign currency forward contracts \| Euro
Derivative Instrument Detail
Number of Instruments \| instrument	7	7	7
Notional Amount \| €			€ 2,105
Fair value, foreign currency derivatives	$ 414
Not Designated as Hedging Instrument \| Foreign currency forward contracts \| NOK
Derivative Instrument Detail
Number of Instruments \| instrument	7	7	7
Notional Amount \| kr		kr 5,733
Fair value, foreign currency derivatives	$ 66