Segment and Related Information, Sales By Product Category (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2020	Mar. 31, 2019
Revenue from External Customer [Abstract]
Net sales	$ 417.5	$ 437.7
Performance Materials [Member]
Revenue from External Customer [Abstract]
Net sales	186.2	199.2
Specialty Minerals [Member]
Revenue from External Customer [Abstract]
Net sales	137.1	144.4
Refractories [Member]
Revenue from External Customer [Abstract]
Net sales	69.0	73.8
Energy Services [Member]
Revenue from External Customer [Abstract]
Net sales	25.2	20.3
Metalcasting [Member]
Revenue from External Customer [Abstract]
Net sales	61.7	73.2
Metalcasting [Member] | Performance Materials [Member]
Revenue from External Customer [Abstract]
Net sales	61.7	73.2
Household, Personal Care and Specialty Products [Member]
Revenue from External Customer [Abstract]
Net sales	96.2	94.8
Household, Personal Care and Specialty Products [Member] | Performance Materials [Member]
Revenue from External Customer [Abstract]
Net sales	96.2	94.8
Environmental Products [Member]
Revenue from External Customer [Abstract]
Net sales	11.5	15.9
Environmental Products [Member] | Performance Materials [Member]
Revenue from External Customer [Abstract]
Net sales	11.5	15.9
Building Materials [Member]
Revenue from External Customer [Abstract]
Net sales	16.8	15.3
Building Materials [Member] | Performance Materials [Member]
Revenue from External Customer [Abstract]
Net sales	16.8	15.3
Paper PCC [Member]
Revenue from External Customer [Abstract]
Net sales	85.1	91.5
Paper PCC [Member] | Specialty Minerals [Member]
Revenue from External Customer [Abstract]
Net sales	85.1	91.5
Specialty PCC [Member]
Revenue from External Customer [Abstract]
Net sales	17.5	18.1
Specialty PCC [Member] | Specialty Minerals [Member]
Revenue from External Customer [Abstract]
Net sales	17.5	18.1
Ground Calcium Carbonate [Member]
Revenue from External Customer [Abstract]
Net sales	22.6	22.3
Ground Calcium Carbonate [Member] | Specialty Minerals [Member]
Revenue from External Customer [Abstract]
Net sales	22.6	22.3
Talc [Member]
Revenue from External Customer [Abstract]
Net sales	11.9	12.5
Talc [Member] | Specialty Minerals [Member]
Revenue from External Customer [Abstract]
Net sales	11.9	12.5
Refractory Products [Member]
Revenue from External Customer [Abstract]
Net sales	55.8	62.0
Refractory Products [Member] | Refractories [Member]
Revenue from External Customer [Abstract]
Net sales	55.8	62.0
Metallurgical Products [Member]
Revenue from External Customer [Abstract]
Net sales	13.2	11.8
Metallurgical Products [Member] | Refractories [Member]
Revenue from External Customer [Abstract]
Net sales	$ 13.2	$ 11.8