Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Disaggregation of Revenue [Abstract]
Net Sales	$ 464.1	$ 424.4	$ 1,360.1	$ 1,243.5
Metalcasting [Member]
Disaggregation of Revenue [Abstract]
Net Sales	77.8	73.6	245.8	215.9
Household, Personal Care & Specialty Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales	71.9	42.5	179.2	123.3
Environmental Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales	26.3	21.6	64.2	51.8
Building Materials [Member]
Disaggregation of Revenue [Abstract]
Net Sales	18.0	19.9	54.9	57.5
Basic Minerals [Member]
Disaggregation of Revenue [Abstract]
Net Sales	25.5	31.2	77.2	90.5
Paper PCC [Member]
Disaggregation of Revenue [Abstract]
Net Sales	93.1	96.3	284.6	282.0
Specialty PCC [Member]
Disaggregation of Revenue [Abstract]
Net Sales	16.9	16.4	51.2	50.8
Ground Calcium Carbonate [Member]
Disaggregation of Revenue [Abstract]
Net Sales	23.0	22.3	70.7	67.1
Talc [Member]
Disaggregation of Revenue [Abstract]
Net Sales	13.3	12.7	40.3	41.0
Refractory Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales	66.7	56.6	195.7	169.4
Metallurgical Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales	12.4	12.3	38.3	38.6
Performance Materials [Member]
Disaggregation of Revenue [Abstract]
Net Sales	219.5	188.8	621.3	539.0
Performance Materials [Member] | Metalcasting [Member]
Disaggregation of Revenue [Abstract]
Net Sales	77.8	73.6	245.8	215.9
Performance Materials [Member] | Household, Personal Care & Specialty Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales	71.9	42.5	179.2	123.3
Performance Materials [Member] | Environmental Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales	26.3	21.6	64.2	51.8
Performance Materials [Member] | Building Materials [Member]
Disaggregation of Revenue [Abstract]
Net Sales	18.0	19.9	54.9	57.5
Performance Materials [Member] | Basic Minerals [Member]
Disaggregation of Revenue [Abstract]
Net Sales	25.5	31.2	77.2	90.5
Specialty Minerals [Member]
Disaggregation of Revenue [Abstract]
Net Sales	146.3	147.7	446.8	440.9
Specialty Minerals [Member] | Paper PCC [Member]
Disaggregation of Revenue [Abstract]
Net Sales	93.1	96.3	284.6	282.0
Specialty Minerals [Member] | Specialty PCC [Member]
Disaggregation of Revenue [Abstract]
Net Sales	16.9	16.4	51.2	50.8
Specialty Minerals [Member] | Ground Calcium Carbonate [Member]
Disaggregation of Revenue [Abstract]
Net Sales	23.0	22.3	70.7	67.1
Specialty Minerals [Member] | Talc [Member]
Disaggregation of Revenue [Abstract]
Net Sales	13.3	12.7	40.3	41.0
Refractories [Member]
Disaggregation of Revenue [Abstract]
Net Sales	79.1	68.9	234.0	208.0
Refractories [Member] | Refractory Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales	66.7	56.6	195.7	169.4
Refractories [Member] | Metallurgical Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales	12.4	12.3	38.3	38.6
Energy Services [Member]
Disaggregation of Revenue [Abstract]
Net Sales	$ 19.2	$ 19.0	$ 58.0	$ 55.6