Segment Information Capital Expenditures (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting, Other Significant Reconciling Item [Line Items]
Capital expenditures	$ 143.8	$ 120.1	$ 414.4	$ 343.6
Passive Safety
Segment Reporting, Other Significant Reconciling Item [Line Items]
Capital expenditures	123.1	96.2	341.9	269.5
Electronics
Segment Reporting, Other Significant Reconciling Item [Line Items]
Capital expenditures	19.8	22.8	69.9	66.8
Corporate and other
Segment Reporting, Other Significant Reconciling Item [Line Items]
Capital expenditures	$ 0.9	$ 1.1	$ 2.6	$ 7.3