Segment and Related Information, Sales By Product Category (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jul. 04, 2021	Jun. 28, 2020	Jul. 04, 2021	Jun. 28, 2020
Segment and Related Information [Abstract]
Net sales	$ 455.6	$ 357.2	$ 908.2	$ 774.7
Metalcasting [Member]
Segment and Related Information [Abstract]
Net sales	80.5	52.8	162.2	114.5
Household, Personal Care & Specialty Products [Member]
Segment and Related Information [Abstract]
Net sales	102.6	87.9	212.0	184.1
Environmental Products [Member]
Segment and Related Information [Abstract]
Net sales	39.9	37.6	65.9	74.3
Building Materials [Member]
Segment and Related Information [Abstract]
Net sales	15.4	13.2	29.2	30.0
Paper PCC [Member]
Segment and Related Information [Abstract]
Net sales	85.8	65.5	175.4	150.6
Specialty PCC [Member]
Segment and Related Information [Abstract]
Net sales	18.5	14.9	38.9	32.4
Ground Calcium Carbonate [Member]
Segment and Related Information [Abstract]
Net sales	25.5	20.6	49.5	43.2
Talc [Member]
Segment and Related Information [Abstract]
Net sales	12.9	8.8	26.7	20.7
Refractory Products [Member]
Segment and Related Information [Abstract]
Net sales	58.0	47.1	116.8	102.9
Metallurgical Products [Member]
Segment and Related Information [Abstract]
Net sales	$ 16.5	$ 8.8	$ 31.6	$ 22.0