Significant Accounting Policies - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) customer	Dec. 31, 2018 USD ($) customer	Dec. 31, 2017 customer	Jan. 01, 2019 USD ($)
Significant Accounting Policies [Line Items]
Deferred financing costs recorded as a non-current asset	$ 3.7	$ 2.2
Net deferred financing costs recorded as a non-current contra liability	4.2	4.8
Allowance for doubtful accounts	0.6	$ 0.3
Operating lease, right of use assets	$ 66.5
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Operating lease, liabilities	$ 66.5
Accounting Standards Update 2016-02
Significant Accounting Policies [Line Items]
Operating lease, right of use assets				$ 50.0
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]				us-gaap:OtherAssetsNoncurrent
Operating lease, liabilities				$ 50.0
Operating Lease, Liability, Statement of Financial Position [Extensible List]				hxl:AccruedLiabilitiesCurrentAndOtherLiabilitiesNonCurrent
Net sales | Customer concentration
Significant Accounting Policies [Line Items]
Number of major customers | customer	2	2	2
Two customers and their related subcontractors | Net sales | Customer concentration
Significant Accounting Policies [Line Items]
Concentration percentage (as a percent)	64.00%	66.00%	69.00%
Minimum | Building and improvements
Significant Accounting Policies [Line Items]
Useful life	10 years
Minimum | Machinery and equipment
Significant Accounting Policies [Line Items]
Useful life	3 years
Minimum | Software
Significant Accounting Policies [Line Items]
Finite lived intangible assets, useful life	3 years
Maximum | Building and improvements
Significant Accounting Policies [Line Items]
Useful life	40 years
Maximum | Machinery and equipment
Significant Accounting Policies [Line Items]
Useful life	25 years
Maximum | Software
Significant Accounting Policies [Line Items]
Finite lived intangible assets, useful life	10 years
Aerospace Composites Malaysia Sdn. Bhd.
Significant Accounting Policies [Line Items]
Interest in affiliated company, accounted for using equity method of accounting (as a percent)	50.00%
Hexcut Services
Significant Accounting Policies [Line Items]
Interest in affiliated company, accounted for using equity method of accounting (as a percent)	25.00%