Fair Value Measurements - Additional Information (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018 USD ($) item Liability	Dec. 31, 2017 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Number of counterparties, which experienced significant downgrades | item	0
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair value measurement with unobservable inputs reconciliation, number of liabilities | Liability	1
Level 3 | OPM Acquisition
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Acquisition of fair value liabilities, contingent consideration	$ 3.0	$ 2.9
Level 2 | Fair Value Measured on Recurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	2.2	16.7
Derivative liabilities	18.4	$ 3.3
Level 2 | Fair Value Measured on Recurring Basis | Interest Rate Swap Agreements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	$ 0.6
Derivative Asset, Measurement Input [Extensible List]	hxl:MeasurementInputLIBORYieldCurvesMember
Derivative liabilities	$ 0.6
Derivative Liability, Measurement Input [Extensible List]	hxl:MeasurementInputLIBORYieldCurvesMember
Level 2 | Fair Value Measured on Recurring Basis | Foreign Currency Forward Exchange Contracts
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	$ 1.6
Derivative Asset, Measurement Input [Extensible List]	us-gaap:MeasurementInputQuotedPriceMember
Derivative liabilities	$ 15.3
Derivative Liability, Measurement Input [Extensible List]	us-gaap:MeasurementInputQuotedPriceMember
Level 2 | Fair Value Measured on Recurring Basis | Commodity Swap Agreements
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative liabilities	$ 2.5
Derivative Liability, Measurement Input [Extensible List]	us-gaap:MeasurementInputQuotedPriceMember