Schedule of Goodwill (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2017 USD ($)
Goodwill [Line Items]
Carrying amount at beginning of year	$ 1,870.7
Acquisition	16.9
Effect of currency translation	17.3
Carrying amount at end of year	1,904.9
Passive Safety
Goodwill [Line Items]
Carrying amount at beginning of year	1,380.6
Effect of currency translation	13.1
Carrying amount at end of year	1,393.7
Electronics
Goodwill [Line Items]
Carrying amount at beginning of year	490.1
Acquisition	16.9
Effect of currency translation	4.2
Carrying amount at end of year	$ 511.2