Revenue Recognition - Disaggregates Revenue for Each Reportable Segment and Geographic Region (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation Of Revenue [Line Items]
Net sales	$ 482.8	$ 240.4
North America (primarily U.S.) [Member]
Disaggregation Of Revenue [Line Items]
Net sales	273.0	125.7
Europe Excluding Germany [Member]
Disaggregation Of Revenue [Line Items]
Net sales	81.7	44.2
Germany [Member]
Disaggregation Of Revenue [Line Items]
Net sales	62.2	49.3
Asia And Other [Member]
Disaggregation Of Revenue [Line Items]
Net sales	65.9	21.2
Operating Segments [Member] | Power Transmission Technologies [Member]
Disaggregation Of Revenue [Line Items]
Net sales	234.9	$ 240.4
Operating Segments [Member] | Automation & Specialty [Member]
Disaggregation Of Revenue [Line Items]
Net sales	249.1
Intersegment Eliminations [Member]
Disaggregation Of Revenue [Line Items]
Net sales	$ (1.2)