Contingent Liabilities - Additional Information (Detail) € in Millions, Airbags in Millions, $ in Millions		3 Months Ended		9 Months Ended
	Oct. 31, 2024 EUR (€)	Jun. 30, 2025 USD ($) Vehicle	Dec. 31, 2020 Vehicle	Sep. 30, 2026 EUR (€) Vehicle	Sep. 30, 2026 USD ($)	Sep. 30, 2026 EUR (€)	Jun. 30, 2026 USD ($)	Dec. 31, 2025 USD ($)	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)	Oct. 31, 2024 USD ($)	Oct. 31, 2024 EUR (€)	Sep. 05, 2023 Airbags
Loss Contingencies [Line Items]
Product liability insurance receivable \| $		$ 69			$ 82		$ 82	$ 87	$ 85	$ 65
Insurance receivable related to recall \| $					8
Recall of frontal driver and passenger air bag \| Airbags \| Airbags													52
Stellantis \| Maximum
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Portion Not Accrued \| $					209
Stellantis \| Minimum
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Portion Not Accrued \| $					0
Stellantis \| Damages from Product Defects
Loss Contingencies [Line Items]
Number of vehicles recalled \| Vehicle		250,000		178,000
Honda Buckle Recall \| Damages from Product Defects
Loss Contingencies [Line Items]
Number of vehicles recalled \| Vehicle			449,000
Unannounced Recall \| Damages from Product Defects
Loss Contingencies [Line Items]
Product liability insurance receivable \| $					$ 12
BMW Complaint
Loss Contingencies [Line Items]
Product liability insurance receivable \| $											$ 0
Description of antitrust matters				The Company has determined pursuant to ASC 450 that a loss is reasonably possible with respect to the BMW Complaint.
Claiming damages and interest \| €												€ 95
Claiming damages charges \| €	€ 63
BMW Complaint \| Maximum
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Portion Not Accrued \| €												95
BMW Complaint \| Minimum
Loss Contingencies [Line Items]
Loss Contingency, Range of Possible Loss, Portion Not Accrued \| €												€ 0
BMW responded
Loss Contingencies [Line Items]
Claiming damages and interest \| €						€ 95
Claiming damages charges \| €				€ 58