Segment Information Capital Expenditures (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting, Other Significant Reconciling Item [Line Items]
Capital expenditures	$ 580.1	$ 506.8	$ 465.8
Passive Safety
Segment Reporting, Other Significant Reconciling Item [Line Items]
Capital expenditures	465.2	394.7	405.6
Electronics
Segment Reporting, Other Significant Reconciling Item [Line Items]
Capital expenditures	109.6	100.9	53.2
Corporate and other
Segment Reporting, Other Significant Reconciling Item [Line Items]
Capital expenditures	$ 5.3	$ 11.2	$ 7.0