Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Disaggregation of Revenue [Abstract]
Total net sales	$ 388.3	$ 449.3	$ 1,163.0	$ 1,350.8
Performance Materials [Member]
Disaggregation of Revenue [Abstract]
Total net sales	190.6	207.3	550.6	621.9
Performance Materials [Member] | Metalcasting [Member]
Disaggregation of Revenue [Abstract]
Total net sales	66.3	69.0	180.8	218.0
Performance Materials [Member] | Household, Personal Care & Specialty Products [Member]
Disaggregation of Revenue [Abstract]
Total net sales	93.9	94.1	278.0	280.4
Performance Materials [Member] | Environmental Products [Member]
Disaggregation of Revenue [Abstract]
Total net sales	16.9	27.1	48.3	72.0
Performance Materials [Member] | Building Materials [Member]
Disaggregation of Revenue [Abstract]
Total net sales	13.5	17.1	43.5	51.5
Specialty Minerals [Member]
Disaggregation of Revenue [Abstract]
Total net sales	125.1	143.1	372.0	432.6
Specialty Minerals [Member] | Paper PCC [Member]
Disaggregation of Revenue [Abstract]
Total net sales	74.5	90.2	225.1	271.9
Specialty Minerals [Member] | Specialty PCC [Member]
Disaggregation of Revenue [Abstract]
Total net sales	17.3	17.7	49.7	53.1
Specialty Minerals [Member] | Ground Calcium Carbonate [Member]
Disaggregation of Revenue [Abstract]
Total net sales	23.2	23.0	66.4	70.1
Specialty Minerals [Member] | Talc [Member]
Disaggregation of Revenue [Abstract]
Total net sales	10.1	12.2	30.8	37.5
Refractories [Member]
Disaggregation of Revenue [Abstract]
Total net sales	59.3	73.4	184.2	224.7
Refractories [Member] | Refractory Products [Member]
Disaggregation of Revenue [Abstract]
Total net sales	48.8	61.3	151.7	184.3
Refractories [Member] | Metallurgical Products [Member]
Disaggregation of Revenue [Abstract]
Total net sales	10.5	12.1	32.5	40.4
Energy Services [Member]
Disaggregation of Revenue [Abstract]
Total net sales	$ 13.3	$ 25.5	$ 56.2	$ 71.6