The interest rate on borrowings. [Refer: Borrowings]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

The discount rate applied to cash flow projections for a cash-generating unit (group of units). [Refer: Cash-generating units [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
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- Definition

The nominal or face amount of a financial instrument, used to calculate payments made on that instrument.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
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- Definition

The description of the frequency of interest payment.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Describes the guarantor for borrowings.

+ References

No definition available.

+ Details

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- Definition

Maximum borrowing capacity under the Euro Medium Term Note program.

+ References

No definition available.

+ Details

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Balance Type:	credit
Period Type:	instant

- References

No definition available.

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- Definition

Refers to percentage of portion of note accepted by the entity at the time of settlement.

+ References

No definition available.

+ Details

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- Definition

Refers to percentage of borrowings on original principal amount.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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LOANS, 2007 and 2014 Notes (Details) - USD ($)	12 Months Ended
LOANS, 2007 and 2014 Notes (Details) - USD ($)	Dec. 31, 2017	Oct. 05, 2016
Issuance of notes [Abstract]
Principal amount		$ 8,000,000
Percentage of cash flows discounted at an effective rate	10.126%
2014 EMTN Program [Member] \| Top of Range [Member]
Issuance of notes [Abstract]
Maximum principal amount	$ 400,000,000
2014 Note [Member]
Issuance of notes [Abstract]
Principal amount	$ 255,451,506
Interest rate	9.625%
Frequency of interest payment	Semiannual, payable el May 14 and November 14 of each year
Guarantor	None
2014 Note [Member] \| May 14, 2014 [Member]
Issuance of notes [Abstract]
Percentage of original principal amount	25.00%
2014 Note [Member] \| May 14, 2018 [Member]
Issuance of notes [Abstract]
Percentage of original principal amount	25.00%
2014 Note [Member] \| May 14, 2019 [Member]
Issuance of notes [Abstract]
Percentage of original principal amount	25.00%
2014 Note [Member] \| May 14, 2020 [Member]
Issuance of notes [Abstract]
Percentage of original principal amount	25.00%
2007 Note [Member]
Issuance of notes [Abstract]
Percentage of notes accepted	67.00%