Debt Instrument, Covenant, First Lien Net Leverage Ratio

No definition available.

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Namespace Prefix:	esi_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt Instrument, Covenant, Outstanding Borrowings Leverage Threshold

+ References

No definition available.

+ Details

Name:	esi_DebtInstrumentCovenantOutstandingBorrowingsLeverageThreshold
Namespace Prefix:	esi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line Of Credit Facility, Commitment Fee Stepdown Percentage

+ References

No definition available.

+ Details

Name:	esi_LineOfCreditFacilityCommitmentFeeStepdownPercentage
Namespace Prefix:	esi_
Data Type:	num:percentItemType
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

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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
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Data Type:	xbrli:stringItemType
Balance Type:	na
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

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3255-108585

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

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- Details

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- Details

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Data Type:	na
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- Details

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- Details

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Namespace Prefix:
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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
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Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_MediumTermNotesMember
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Debt - Covenants, Events of Default and Provisions, Subsequent Event (Details) - USD ($)		12 Months Ended
	Jan. 31, 2019	Dec. 31, 2018
Subsequent Event
Debt Instrument [Line Items]
Proceeds from debt	$ 750,000,000
Revolving Credit Facility \| Base Rate
Debt Instrument [Line Items]
Spread on variable rate		2.00%
Senior Notes \| Subsequent Event
Debt Instrument [Line Items]
Face amount	$ 1,080,000,000.00
Commitment fee percentage	0.50%
Commitment fee stepdown percentage	0.375%
Covenant, outstanding borrowings leverage threshold	30.00%
Covenant, first lien net leverage ratio	5.0
Senior Notes \| Subsequent Event \| Eurocurrency Rate
Debt Instrument [Line Items]
Spread on variable rate	2.25%
Senior Notes \| Subsequent Event \| Base Rate
Debt Instrument [Line Items]
Spread on variable rate	1.25%
Line of Credit \| Revolving Credit Facility \| Subsequent Event
Debt Instrument [Line Items]
Face amount	$ 330,000,000
Term Loan \| Subsequent Event
Debt Instrument [Line Items]
Face amount	$ 750,000,000