Debt instrument covenant increase in interest coverage ratio.

No definition available.

Name:	hxl_DebtInstrumentCovenantIncreaseInInterestCoverageRatio
Namespace Prefix:	hxl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the interest coverage ratio required to be maintained under the financial covenant.

+ References

No definition available.

+ Details

Name:	hxl_DebtInstrumentCovenantInterestCoverageRatio
Namespace Prefix:	hxl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument floor interest rate.

+ References

No definition available.

+ Details

Name:	hxl_DebtInstrumentFloorInterestRate
Namespace Prefix:	hxl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Debt instrument maturity year.

+ References

No definition available.

+ Details

Name:	hxl_DebtInstrumentMaturityYear
Namespace Prefix:	hxl_
Data Type:	xbrli:gYearItemType
Balance Type:	na
Period Type:	duration

- Definition

Letters of credit issued amount.

+ References

No definition available.

+ Details

Name:	hxl_LettersOfCreditIssuedAmount
Namespace Prefix:	hxl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum amount available under credit facility to issue letters of credit.

+ References

No definition available.

+ Details

Name:	hxl_MaximumAmountAvailableUnderCreditFacilityToIssueLettersOfCredit
Namespace Prefix:	hxl_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of tranches.

+ References

No definition available.

+ Details

Name:	hxl_NumberOfTranches
Namespace Prefix:	hxl_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of reduction in interest rate on senior notes.

+ References

No definition available.

+ Details

Name:	hxl_PercentageOfReductionInInterestRateOnSeniorNotes
Namespace Prefix:	hxl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The expiration, mandatory redemption, or due date, month and year (YYYY-MM), of the financial instrument issued in exchange for the original debt being converted in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4304-108586

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=98513485&loc=d3e4332-108586

+ Details

Name:	us-gaap_DebtConversionConvertedInstrumentExpirationOrDueDateMonthAndYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:gYearMonthItemType
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

Description of minimum financial levels (for example, tangible net worth and working capital) and achievement of certain financial ratios (for example, working capital ratio and debt service coverage ratio), and adherence to certain clauses which generally require or restrict certain actions (for example, entering into a debt arrangement with equal or greater seniority, and selling or discontinuing a certain business segment or material subsidiary) to be in compliance with the covenant clauses of the debt agreement. May also include a discussion of the adverse consequences that would result if the entity violates or fails to satisfy the covenants.

+ 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))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

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

- Definition

Date the debt agreement requires the first payment to be made, in CCYY-MM-DD format.

+ 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)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

Name:	us-gaap_DebtInstrumentDateOfFirstRequiredPayment1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The reference rate for the variable rate of the debt instrument, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentDescriptionOfVariableRateBasis
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
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

Description of the frequency of periodic payments (monthly, quarterly, annual).

+ 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)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

+ Details

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

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870

Reference 2: 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 3: 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_DebtInstrumentInterestRateEffectivePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Incremental percentage increase (decrease) in the stated rate on a debt instrument.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

+ Details

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

- Definition

Description of the interest rate as being fixed or variable, and, if variable, identification of the index or rate on which the interest rate is based and the number of points or percentage added to that index or rate to set the rate, and other pertinent information, such as frequency of rate resets.

+ References

+ Details

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

- 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

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions).

+ References

+ Details

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

- Definition

The effective interest rate during the reporting period.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateDuringPeriod
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

+ 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

+ Details

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

- Definition

Including the current and noncurrent portions, aggregate carrying value as of the balance sheet date of loans payable (with maturities initially due after one year or beyond the operating cycle if longer).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: 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))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16)(a)(2))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

+ Details

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

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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

- Definition

Amount after unamortized (discount) premium and debt issuance costs of long-term debt classified as noncurrent and excluding amounts to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

+ Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=hxl_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_TreasuryLockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_InterestRateLockCommitmentsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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

Debt - Additional Information (Details) € in Millions, $ in Millions	1 Months Ended	9 Months Ended	12 Months Ended
	Jun. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 EUR (€) tranche	Dec. 31, 2015 USD ($)	May 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Debt Instrument [Line Items]
Borrowings		$ 1,115.2					$ 947.4
Term loan
Debt Instrument [Line Items]
Debt instrument, interest rate terms		The loan has two tranches of which the first tranche for €25 million has a rate of Euribor +1.2% and a final maturity date of June 30, 2023, and a second tranche for €35 million has a rate of Euribor +1.25% with a final maturity date of June 30, 2024. The loans are payable in annual installments that began on June 30, 2017, for the first tranche, and on June 30, 2019, for the second. There is a zero percent floor on the Euribor.
Face value \| €				€ 60
Number of tranches \| tranche				2
Debt instrument, payment terms		annual
Term loan \| Euribor
Debt Instrument [Line Items]
Debt instrument, floor rate				0.00%
Level 2 \| Term loan
Debt Instrument [Line Items]
Outstanding amount under loan		$ 49.0
Maximum
Debt Instrument [Line Items]
Interest coverage ratio required to be maintained		375.00%
Minimum
Debt Instrument [Line Items]
Interest coverage ratio required to be maintained		350.00%
Senior unsecured credit facility- revolving loan due 2024
Debt Instrument [Line Items]
Debt instrument expiration period	2024-06
Debt instrument, interest rate terms	The initial interest rate for the Facility is LIBOR + 1.0%. The interest rate ranges from LIBOR + 0.875% to a maximum of LIBOR + 1.50%, depending upon the better of the Company’s leverage ratio or the credit rating.
Credit facility interest rate basis	LIBOR + 1.0%.
Spread on variable interest rate basis	1.00%
Maximum amount available under credit facility agreement to issue letters of credit		$ 50.0
Letters of credit issued under credit facility		0.0
Undrawn availability under credit facility		$ 621.0
Weighted average interest rate		4.17%
Debt instrument, covenant terms		As defined in the Facility agreement, we are required to maintain a minimum interest coverage ratio of 3.50 (based on the ratio of EBITDA to interest expense) and may not exceed a maximum leverage ratio of 3.75 (based on the ratio of total debt to EBITDA) with a step up to 4.25 allowed following certain acquisitions.
Senior unsecured credit facility- revolving loan due 2024 \| Level 2
Debt Instrument [Line Items]
Borrowings		$ 379.0
Senior unsecured credit facility- revolving loan due 2024 \| Maximum
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 1,000.0					$ 700.0
Credit facility interest rate basis	LIBOR + 1.50%
Spread on variable interest rate basis	1.50%
Debt instrument covenant increase in interest coverage ratio		425.00%
Senior unsecured credit facility- revolving loan due 2024 \| Minimum
Debt Instrument [Line Items]
Credit facility interest rate basis	LIBOR + 0.875%
Spread on variable interest rate basis	0.875%
3.95% senior unsecured notes due 2027
Debt Instrument [Line Items]
Face value			$ 400.0
Debt instrument, interest rate		3.95%	3.95%
Debt instrument, maturity year			2027
Increase in senior notes interest rate			0.25%
Effective interest rate		3.88%
3.95% senior unsecured notes due 2027 \| Treasury Lock \| Interest Lock Agreement
Debt Instrument [Line Items]
Percentage of effective interest rate benefit		0.25%
3.95% senior unsecured notes due 2027 \| Level 2
Debt Instrument [Line Items]
Fair value of senior unsecured notes		$ 415.8
3.95% senior unsecured notes due 2027 \| Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate			5.95%
Tranche one \| Term loan
Debt Instrument [Line Items]
Spread on variable interest rate basis				1.20%
Face value \| €				€ 25
Variable interest rate basis		Euribor +1.2%
Debt instrument, maturity date		Jun. 30, 2023
Beginning date of first required loan payment		Jun. 30, 2017
Tranche two \| Term loan
Debt Instrument [Line Items]
Spread on variable interest rate basis				1.25%
Face value \| €				€ 35
Variable interest rate basis		Euribor +1.25%
Debt instrument, maturity date		Jun. 30, 2024
Beginning date of first required loan payment		Jun. 30, 2019
4.7% senior unsecured notes due 2025
Debt Instrument [Line Items]
Face value					$ 300.0
Debt instrument, interest rate					4.70%
Debt instrument, maturity year					2025
Increase in senior notes interest rate					0.25%
Effective interest rate		4.83%
4.7% senior unsecured notes due 2025 \| Level 2
Debt Instrument [Line Items]
Fair value of senior unsecured notes		$ 324.1
4.7% senior unsecured notes due 2025 \| Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate					6.70%