Debt instrument basis revised spread on LIBOR rate.

No definition available.

Name:	eigi_DebtInstrumentBasisRevisedSpreadOnLiborRate
Namespace Prefix:	eigi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument basis spread on reference rate.

+ References

No definition available.

+ Details

Name:	eigi_DebtInstrumentBasisSpreadOnReferenceRate
Namespace Prefix:	eigi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Gain (Loss) on Redemption

+ References

No definition available.

+ Details

Name:	eigi_DebtInstrumentGainLossonRedemption
Namespace Prefix:	eigi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Debt Instrument, Mandatory Repayment Amount

+ References

No definition available.

+ Details

Name:	eigi_DebtInstrumentMandatoryRepaymentAmount
Namespace Prefix:	eigi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Debt Instrument, Number of Voluntary Redemptions

+ References

No definition available.

+ Details

Name:	eigi_DebtInstrumentNumberofVoluntaryRedemptions
Namespace Prefix:	eigi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument par value percentage.

+ References

No definition available.

+ Details

Name:	eigi_DebtInstrumentParValuePercentage
Namespace Prefix:	eigi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt instrument reference rate.

+ References

No definition available.

+ Details

Name:	eigi_DebtInstrumentReferenceRate
Namespace Prefix:	eigi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt instrument revised LIBOR rate.

+ References

No definition available.

+ Details

Name:	eigi_DebtInstrumentRevisedLiborRate
Namespace Prefix:	eigi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Voluntary Redemption Amount

+ References

No definition available.

+ Details

Name:	eigi_DebtInstrumentVoluntaryRedemptionAmount
Namespace Prefix:	eigi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Long Term Debt, Number Of Mandatory Repayments

+ References

No definition available.

+ Details

Name:	eigi_LongTermDebtNumberOfMandatoryRepayments
Namespace Prefix:	eigi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage price of original principal amount of debt at which debt can be redeemed by the issuer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph e
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

Name:	us-gaap_DebtInstrumentRedemptionPricePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of the cost of borrowed funds accounted for as interest expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6450988&loc=d3e26243-108391

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8736-108599

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (210.5-03(11))
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.9)
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

+ Details

Name:	us-gaap_InterestExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Write-off of amounts previously capitalized as debt issuance cost in an extinguishment of debt.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

+ Details

Name:	us-gaap_WriteOffOfDeferredDebtIssuanceCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=eigi_A2018FirstLienTermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_FederalFundsEffectiveSwapRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=eigi_A2016RevolverCommitmentsMaturingFebruary2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=eigi_A2016RevolverCommitmentsMaturingJune2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=eigi_LiborBasedInterestRateLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=eigi_NonextendedRevolvingLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=eigi_ExtendedRevolvingLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=eigi_AlternateBaseRateLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=eigi_SeniorNotesDueTwoThousandAndTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	eigi_PaymentAxis=eigi_VoluntaryPrepaymentNumberOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	eigi_PaymentAxis=eigi_VoluntaryPrepaymentNumberTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Notes Payable - Additional Information (Detail)	3 Months Ended
Notes Payable - Additional Information (Detail)	Mar. 31, 2020 USD ($) repayment	Mar. 31, 2019 USD ($)	Dec. 31, 2019 USD ($)	Feb. 09, 2016 USD ($)
Long-Term Debt [Line Items]
Interest expense	$ 32,734,000	$ 37,214,000
Revolving Credit Facility
Long-Term Debt [Line Items]
Revolving credit facility maximum borrowing amount	165,000,000.0
Amount of facility unused and available	$ 165,000,000		$ 165,000,000
Commitment fee percentage	0.50%
Term Loan
Long-Term Debt [Line Items]
Debt instrument revised LIBOR rate	3.75%
Reference rate	2.75%
Basis revised spread on LIBOR rate	1.00%
Basis spread on reference rate	2.00%
Number of mandatory repayments \| repayment	1
Mandatory repayments	$ 7,900,000
Term Loan \| London Interbank Offered Rate (LIBOR)
Long-Term Debt [Line Items]
Basis spread on variable rate	1.00%
Term Loan \| Federal Funds Effective Rate
Long-Term Debt [Line Items]
Basis spread on variable rate	0.50%
2016 Revolver Commitments Maturing February 2021 \| Revolving Credit Facility
Long-Term Debt [Line Items]
Revolving credit facility maximum borrowing amount	$ 58,800,000
2016 Revolver Commitments Maturing June 2023 \| Revolving Credit Facility
Long-Term Debt [Line Items]
Revolving credit facility maximum borrowing amount	$ 106,200,000
LIBOR Based Interest Rate Loan \| Revolving Credit Facility \| London Interbank Offered Rate (LIBOR)
Long-Term Debt [Line Items]
Basis revised spread on LIBOR rate	1.00%
LIBOR Based Interest Rate Loan \| Non-extended Revolving Loan
Long-Term Debt [Line Items]
Reference rate	4.00%
LIBOR Based Interest Rate Loan \| Extended Revolving Loan
Long-Term Debt [Line Items]
Reference rate	3.25%
Alternate Base Rate Loans \| Revolving Credit Facility \| Federal Funds Effective Rate
Long-Term Debt [Line Items]
Basis spread on variable rate	0.50%
Alternate Base Rate Loans \| Non-extended Revolving Loan
Long-Term Debt [Line Items]
Basis revised spread on LIBOR rate	3.00%
Alternate Base Rate Loans \| Extended Revolving Loan
Long-Term Debt [Line Items]
Basis revised spread on LIBOR rate	2.25%
Notes
Long-Term Debt [Line Items]
Original note balance				$ 350,000,000.0
Par value percentage				98.065%
Interest rate, stated percentage	10.875%	10.875%		10.875%
Number of voluntary redemptions \| repayment	2
Voluntary redemption amount	$ 3,000,000.0
Redemption price, percentage	101.00%
Write off of Deferred Debt Issuance Cost	$ 100,000
Gain (loss) on redemption of debt	0.0
Voluntary Prepayment Number One \| Notes
Long-Term Debt [Line Items]
Voluntary redemption amount	$ 1,300,000
Redemption price, percentage	98.50%
Voluntary Prepayment Number Two \| Notes
Long-Term Debt [Line Items]
Voluntary redemption amount	$ 1,700,000
Redemption price, percentage	93.00%