Retirement Benefit Plans - Changes in Plan Assets and Benefit Obligations in AOCL (Details) - Foreign Plan [Member] - Pension Plan [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Changes in prior service cost recognized in accumulated other comprehensive loss:
Accumulated other comprehensive income at beginning of year	$ 4.0	$ 0.5
Recognized prior service credit	(0.2)	(0.1)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Curtailment	0.0	0.0	$ 0.0
Total recognized in accumulated other comprehensive income at December 31	$ 3.9	$ 4.0	$ 0.5