Schedule of Disaggregated Revenue by Products and Region (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Net sales		$ 1,047.6	$ 2,154.7	$ 2,893.4	$ 4,328.7
Airbag Products and Other
Disaggregation Of Revenue [Line Items]
Net sales	[1]	653.8	1,435.7	1,855.9	2,883.4
Seatbelt Products
Disaggregation Of Revenue [Line Items]
Net sales	[1]	393.8	719.0	1,037.5	1,445.3
China
Disaggregation Of Revenue [Line Items]
Net sales		366.4	349.5	563.9	680.0
Japan
Disaggregation Of Revenue [Line Items]
Net sales		104.6	191.1	307.6	399.2
Rest of Asia
Disaggregation Of Revenue [Line Items]
Net sales		116.9	217.1	313.6	429.3
Americas
Disaggregation Of Revenue [Line Items]
Net sales		213.4	758.1	885.5	1,501.1
Europe
Disaggregation Of Revenue [Line Items]
Net sales		$ 246.3	$ 638.9	$ 822.8	$ 1,319.1

[1] Including Corporate and other sales.