Revenue from Continuing Operations Disaggregated by Primary Regions and Products (Detail) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation Of Revenue [Line Items]
Net sales		$ 2,192.8	$ 2,033.0	$ 2,211.5	$ 2,240.9	$ 2,158.7	$ 1,952.6	$ 1,983.9	$ 2,041.6	$ 8,678.2	$ 8,136.8	$ 7,921.6
Airbag Products and Other
Disaggregation Of Revenue [Line Items]
Net sales	[1]									5,698.6	5,343.2	5,256.4
Seatbelt Products
Disaggregation Of Revenue [Line Items]
Net sales	[1]									2,979.6	2,793.6	2,665.2
China
Disaggregation Of Revenue [Line Items]
Net sales										1,522.2	1,421.2	1,385.4
Japan
Disaggregation Of Revenue [Line Items]
Net sales										827.9	787.0	718.6
Rest of Asia
Disaggregation Of Revenue [Line Items]
Net sales										844.8	789.9	726.2
Americas
Disaggregation Of Revenue [Line Items]
Net sales										2,735.1	2,435.2	2,548.0
Europe
Disaggregation Of Revenue [Line Items]
Net sales										$ 2,748.2	$ 2,703.5	$ 2,543.4

[1] Including Corporate and other sales.