Financial Instruments (Schedule of Composition of Derivatives) (Details) - EUR (€) € in Thousands	Dec. 31, 2020	Dec. 31, 2019
Disclosure of detailed information about financial instruments [line items]
Derivatives presented under current assets	€ 78	€ 94
Derivatives presented under non-current assets	10,238	5,162
Derivatives presented under current liabilities	1,378	766
Derivatives presented under non-current liabilities	(8,336)	(7,263)
Financial power swap [Member]
Disclosure of detailed information about financial instruments [line items]
Derivatives presented under non-current assets	10,238	4,967
Forward contract [Member]
Disclosure of detailed information about financial instruments [line items]
Derivatives presented under current assets	66
Derivatives presented under non-current assets		92
Derivatives presented under non-current liabilities		(344)
Currency swap [Member]
Disclosure of detailed information about financial instruments [line items]
Derivatives presented under current assets	12	94
Derivatives presented under non-current assets		103
Derivatives presented under non-current liabilities	(144)
Swap contract [Member]
Disclosure of detailed information about financial instruments [line items]
Derivatives presented under current liabilities	(1,378)	(766)
Derivatives presented under non-current liabilities	€ (8,192)	€ (6,919)

The amount of current derivative financial assets. [Refer: Derivative financial assets]

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2020-01-01
-Paragraph 55
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=1&code=ifrs-tx-2020-en-r&anchor=para_55&doctype=Standard
-URIDate 2020-01-01

+ Details

Name:	ifrs-full_CurrentDerivativeFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of current derivative financial liabilities. [Refer: Derivative financial liabilities]

+ References

+ Details

Name:	ifrs-full_CurrentDerivativeFinancialLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table.

+ References

No definition available.

+ Details

Name:	ifrs-full_DisclosureOfFinancialInstrumentsLineItems
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of non-current derivative financial assets. [Refer: Derivative financial assets]

+ References

+ Details

Name:	ifrs-full_NoncurrentDerivativeFinancialAssets
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of non-current derivative financial liabilities. [Refer: Derivative financial liabilities]

+ References

+ Details

Name:	ifrs-full_NoncurrentDerivativeFinancialLiabilities
Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=ello_FinancialPowerSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=ifrs-full_ForwardContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=ello_CurrencySwap1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	ifrs-full_ClassesOfFinancialAssetsAxis=ifrs-full_SwapContractMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: