Revenue from Contracts with Customers (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Abstract]
Net Sales	$ 447.5	$ 464.1	$ 464.7	$ 431.3	$ 432.1	$ 424.5	$ 414.1	$ 405.0	$ 1,807.6	$ 1,675.7	$ 1,638.0
Metalcasting [Member]
Disaggregation of Revenue [Abstract]
Net Sales									328.9	294.3	258.0
Household, Personal Care and Specialty Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales									248.8	169.6	171.2
Environmental Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales									80.3	67.7	78.9
Building Materials [Member]
Disaggregation of Revenue [Abstract]
Net Sales									70.4	78.2	74.1
Basic Minerals [Member]
Disaggregation of Revenue [Abstract]
Net Sales									99.7	125.0	103.9
Paper PCC [Member]
Disaggregation of Revenue [Abstract]
Net Sales									378.5	377.7	387.9
Specialty PCC [Member]
Disaggregation of Revenue [Abstract]
Net Sales									66.9	66.0	64.3
Ground Calcium Carbonate [Member]
Disaggregation of Revenue [Abstract]
Net Sales									91.0	87.3	83.6
Talc [Member]
Disaggregation of Revenue [Abstract]
Net Sales									52.9	53.8	55.7
Refractory Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales									261.1	226.9	219.0
Metallurgical Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales									50.8	52.5	55.5
Performance Materials [Member]
Disaggregation of Revenue [Abstract]
Net Sales	206.8	219.5	214.5	187.3	195.8	188.8	180.3	169.9	828.1	734.8	686.1
Performance Materials [Member] | Metalcasting [Member]
Disaggregation of Revenue [Abstract]
Net Sales									328.9	294.3	258.0
Performance Materials [Member] | Household, Personal Care and Specialty Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales									248.8	169.6	171.2
Performance Materials [Member] | Environmental Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales									80.3	67.7	78.9
Performance Materials [Member] | Building Materials [Member]
Disaggregation of Revenue [Abstract]
Net Sales									70.4	78.2	74.1
Performance Materials [Member] | Basic Minerals [Member]
Disaggregation of Revenue [Abstract]
Net Sales									99.7	125.0	103.9
Specialty Minerals [Member]
Disaggregation of Revenue [Abstract]
Net Sales	142.5	146.3	150.9	149.6	143.9	147.7	147.0	146.2	589.3	584.8	591.5
Specialty Minerals [Member] | Paper PCC [Member]
Disaggregation of Revenue [Abstract]
Net Sales									378.5	377.7	387.9
Specialty Minerals [Member] | Specialty PCC [Member]
Disaggregation of Revenue [Abstract]
Net Sales									66.9	66.0	64.3
Specialty Minerals [Member] | Ground Calcium Carbonate [Member]
Disaggregation of Revenue [Abstract]
Net Sales									91.0	87.3	83.6
Specialty Minerals [Member] | Talc [Member]
Disaggregation of Revenue [Abstract]
Net Sales									52.9	53.8	55.7
Refractories [Member]
Disaggregation of Revenue [Abstract]
Net Sales	77.9	79.1	79.6	75.3	71.3	69.0	68.9	70.2	311.9	279.4	274.5
Refractories [Member] | Refractory Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales									261.1	226.9	219.0
Refractories [Member] | Metallurgical Products [Member]
Disaggregation of Revenue [Abstract]
Net Sales									50.8	52.5	55.5
Energy Services [Member]
Disaggregation of Revenue [Abstract]
Net Sales	$ 20.3	$ 19.2	$ 19.7	$ 19.1	$ 21.1	$ 19.0	$ 17.9	$ 18.7	$ 78.3	$ 76.7	$ 85.9