Risk Management and Use of Derivative Financial Instruments (Details 7) - Jun. 30, 2015 $ in Thousands	USD ($) instrument
Derivative Instrument Detail
Fair value, foreign currency derivatives	$ 42,850
Not designated \| Foreign currency contract \| Euro
Derivative Instrument Detail
Derivative number of instruments \| instrument	2
Derivative notional amount	$ 90,000
Fair value, foreign currency derivatives	$ 2,200
Cash Flow Hedging \| Designated as hedging \| Foreign currency contract \| Euro
Derivative Instrument Detail
Derivative number of instruments \| instrument	88
Derivative notional amount	$ 176,175
Fair value, foreign currency derivatives	$ 35,980
Cash Flow Hedging \| Designated as hedging \| Foreign currency contract \| NOK
Derivative Instrument Detail
Derivative number of instruments \| instrument	17
Derivative notional amount	$ 12,239
Fair value, foreign currency derivatives	$ 100
Net Investment Hedging \| Designated as hedging \| Foreign currency contract \| NOK
Derivative Instrument Detail
Derivative number of instruments \| instrument	5
Derivative notional amount	$ 7,996
Fair value, foreign currency derivatives	$ 65
Net Investment Hedging \| Designated as hedging \| Foreign currency contract \| Yen
Derivative Instrument Detail
Derivative number of instruments \| instrument	11
Derivative notional amount	$ 1,077,804
Fair value, foreign currency derivatives	$ 4,505

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=35706170&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=35706170&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=35706170&loc=SL5624163-113959

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