Segment Information Net Sales Including Intersegment Sales (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales	$ 2,729.2	$ 2,500.4	$ 2,544.9	$ 2,608.1	$ 2,603.8	$ 2,461.3	$ 2,578.5	$ 2,430.0	$ 10,382.6	$ 10,073.6	$ 9,169.6
Operating Segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales									10,456.8	10,134.4	9,209.9
Operating Segments | Passive Safety
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales									8,134.6	7,918.8	7,621.2
Operating Segments | Electronics
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales									2,322.2	2,215.6	1,588.7
Corporate and other
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales									3.1	5.8	14.7
Intersegment Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Net sales									$ (77.3)	$ (66.6)	$ (55.0)