Segment Information Income Before Income Taxes (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment operating income	$ 157.8	$ 174.8	$ 446.5	$ 505.9
Interest and other non-operating expenses, net	(6.6)	(19.7)	(39.2)	(48.0)
Income from equity method investments	0.6	1.4	3.5	5.8
Income before income taxes	151.8	156.5	410.8	463.7
Operating Segments
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment operating income	157.2	159.4	436.9	462.3
Operating Segments | Passive Safety
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment operating income	145.8	144.6	404.7	410.7
Operating Segments | Electronics
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment operating income	11.4	14.8	32.2	51.6
Corporate and other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Segment operating income	$ 0.6	$ 15.4	$ 9.6	$ 43.6