Segment Assets (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Assets	$ 7,547.9	$ 7,510.7
Driveline [Member]
Segment Reporting Information [Line Items]
Assets	3,621.5	3,529.2
Metal Forming [Member]
Segment Reporting Information [Line Items]
Assets	2,657.2	2,723.0
Casting [Member]
Segment Reporting Information [Line Items]
Assets	673.4	664.7
Corporate and Eliminations [Member]
Segment Reporting Information [Line Items]
Assets	$ 595.8	$ 593.8