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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5579245-113959

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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://www.xbrl.org/2003/role/presentationRef
-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=56946850&loc=SL5624163-113959

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Risk Management and Use of Derivative Financial Instruments (Details 7) € in Thousands, ¥ in Thousands, NOK in Thousands, $ in Thousands	Dec. 31, 2015 USD ($) instrument	Dec. 31, 2015 JPY (¥) instrument	Dec. 31, 2015 NOK instrument	Dec. 31, 2015 EUR (€) instrument
Derivative Instrument Detail
Fair value, foreign currency derivatives	$ 41,745
Cash Flow Hedging \| Designated as hedging \| Foreign currency forward contracts \| Euro
Derivative Instrument Detail
Derivative number of instruments \| instrument	79	79	79	79
Derivative notional amount \| €				€ 157,866
Fair value, foreign currency derivatives	$ 37,344
Cash Flow Hedging \| Designated as hedging \| Foreign currency forward contracts \| NOK
Derivative Instrument Detail
Derivative number of instruments \| instrument	17	17	17	17
Derivative notional amount \| NOK			NOK 12,239
Fair value, foreign currency derivatives	$ 258
Cash Flow Hedging \| Designated as hedging \| Foreign currency collars \| Euro
Derivative Instrument Detail
Derivative number of instruments \| instrument	1	1	1	1
Derivative notional amount \| €				€ 6,100
Fair value, foreign currency derivatives	$ (109)
Cash Flow Hedging \| Designated as hedging \| Foreign currency collars \| NOK
Derivative Instrument Detail
Derivative number of instruments \| instrument	3	3	3	3
Derivative notional amount \| NOK			NOK 2,000
Fair value, foreign currency derivatives	$ 2
Net Investment Hedging \| Designated as hedging \| Foreign currency forward contracts \| NOK
Derivative Instrument Detail
Derivative number of instruments \| instrument	5	5	5	5
Derivative notional amount \| NOK			NOK 7,996
Fair value, foreign currency derivatives	$ 168
Net Investment Hedging \| Designated as hedging \| Foreign currency forward contracts \| JPY
Derivative Instrument Detail
Derivative number of instruments \| instrument	9	9	9	9
Derivative notional amount \| ¥		¥ 991,401
Fair value, foreign currency derivatives	$ 4,080
Net Investment Hedging \| Designated as hedging \| Foreign currency collars \| NOK
Derivative Instrument Detail
Derivative number of instruments \| instrument	1	1	1	1
Derivative notional amount \| NOK			NOK 2,500
Fair value, foreign currency derivatives	$ 2