Financial Instruments - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other long-term assets	$ 11.2	$ 15.2	$ 11.2	$ 15.2
Impairment loss	4.0	5.0	4.0	5.0
Interest expense			99.6	92.0	$ 84.1
Tax benefits (expense) related to derivative instruments and hedging activities recognized in other comprehensive income (loss)			(0.8)	(5.5)	(3.3)
Derivative contracts transfers in to Level 3 fair value hierarchy			0.0	0.0
Lear Fawsn
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Noncontrolling interests, fair value					14.0
Fair value of previously held equity interest in acquiree					23.0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative contracts classified within Level 3 of fair value hierarchy	0.0	0.0	0.0	0.0
Level 3 | Lear Fawsn
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible assets					7.5
Property, plant and equipment, fair value					11.0
Noncontrolling interests, fair value					$ 14.0
Designated as Hedging Instrument | Foreign currency contracts, net | Derivative instruments and hedging
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Pretax net losses related to derivative instruments and hedging activities in accumulated other comprehensive loss	$ 4.7	19.4	4.7	19.4
Net investment hedges | Designated as Hedging Instrument | Interest rate swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Interest expense			$ 6.5	1.8
Estimate of Fair Value Measurement | Level 3 | Xevo Inc.
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Intangible assets		$ 90.1		$ 90.1