Segment and Related Information, Sales by Product Category (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from External Customer [Abstract]
Net sales	$ 440.2	$ 449.3	$ 463.8	$ 437.7	$ 447.5	$ 464.1	$ 464.7	$ 431.3	$ 1,791.0	$ 1,807.6	$ 1,675.7
Metalcasting [Member]
Revenue from External Customer [Abstract]
Net sales									291.2	328.9	294.3
Household, Personal Care & Specialty Products [Member]
Revenue from External Customer [Abstract]
Net sales									376.6	348.5	294.6
Environmental Products [Member]
Revenue from External Customer [Abstract]
Net sales									86.6	80.3	67.7
Building Materials [Member]
Revenue from External Customer [Abstract]
Net sales									68.9	70.4	78.2
Paper PCC [Member]
Revenue from External Customer [Abstract]
Net sales									364.9	378.5	377.7
Specialty PCC [Member]
Revenue from External Customer [Abstract]
Net sales									69.1	66.9	66.0
Ground Calcium Carbonate [Member]
Revenue from External Customer [Abstract]
Net sales									91.3	91.0	87.3
Talc [Member]
Revenue from External Customer [Abstract]
Net sales									49.1	52.9	53.8
Refractory Products [Member]
Revenue from External Customer [Abstract]
Net sales									244.8	261.1	226.9
Metallurgical Products [Member]
Revenue from External Customer [Abstract]
Net sales									53.3	50.8	52.5
Energy Services [Member]
Revenue from External Customer [Abstract]
Net sales									$ 95.2	$ 78.3	$ 76.7