Segment and Related Information, Sales By Product Category (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Apr. 01, 2018
Revenue from External Customer [Abstract]
Net sales	$ 437.7	$ 431.3
Metalcasting [Member]
Revenue from External Customer [Abstract]
Net sales	73.2	79.2
Household, Personal Care and Specialty Products [Member]
Revenue from External Customer [Abstract]
Net sales	74.9	48.7
Environmental Products [Member]
Revenue from External Customer [Abstract]
Net sales	15.9	12.7
Building Materials [Member]
Revenue from External Customer [Abstract]
Net sales	15.3	18.9
Basic Minerals [Member]
Revenue from External Customer [Abstract]
Net sales	19.9	27.8
Paper PCC [Member]
Revenue from External Customer [Abstract]
Net sales	91.5	97.0
Specialty PCC [Member]
Revenue from External Customer [Abstract]
Net sales	18.1	17.0
Ground Calcium Carbonate [Member]
Revenue from External Customer [Abstract]
Net sales	22.3	22.5
Talc [Member]
Revenue from External Customer [Abstract]
Net sales	12.5	13.1
Refractory Products [Member]
Revenue from External Customer [Abstract]
Net sales	62.0	62.3
Metallurgical Products [Member]
Revenue from External Customer [Abstract]
Net sales	11.8	13.0
Energy Services [Member]
Revenue from External Customer [Abstract]
Net sales	$ 20.3	$ 19.1