Segment and Related Information, Sales By Product Category (Details) - USD ($) $ in Millions	3 Months Ended					6 Months Ended		12 Months Ended
	Jul. 02, 2017	Dec. 31, 2016	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Jul. 02, 2017	Jul. 03, 2016	Dec. 31, 2016
Revenue from External Customer [Line Items]
Net Sales	$ 414.1			$ 427.0		$ 819.1	$ 837.2
Paper PCC [Member]
Revenue from External Customer [Line Items]
Net Sales	92.3			97.0		185.7	200.2
Specialty PCC [Member]
Revenue from External Customer [Line Items]
Net Sales	17.4			17.1		34.4	33.8
Talc [Member]
Revenue from External Customer [Line Items]
Net Sales	14.0			13.8		28.3	28.8
Ground Calcium Carbonate [Member]
Revenue from External Customer [Line Items]
Net Sales	23.3			22.7		44.8	43.4
Refractory Products [Member]
Revenue from External Customer [Line Items]
Net Sales	56.1			58.9		112.8	112.3
Metallurgical Products [Member]
Revenue from External Customer [Line Items]
Net Sales	12.8			15.0		26.3	30.8
Metalcasting [Member]
Revenue from External Customer [Line Items]
Net Sales	75.7	$ 66.9	$ 63.1	68.0	$ 60.0	142.3	128.0	$ 258.0
Household, Personal Care and Specialty Products [Member]
Revenue from External Customer [Line Items]
Net Sales	39.7	39.8	42.1	44.0	45.3	80.8	89.3	171.2
Basic Minerals [Member]
Revenue from External Customer [Line Items]
Net Sales	25.1	36.8	22.3	24.3	20.5	59.3	44.8	103.9
Environmental Products [Member]
Revenue from External Customer [Line Items]
Net Sales	19.6	14.4	24.6	26.5	13.4	30.2	39.9	78.9
Building Materials [Member]
Revenue from External Customer [Line Items]
Net Sales	20.2	$ 17.1	$ 16.9	19.7	$ 20.4	37.6	40.1	$ 74.1
Energy Services [Member]
Revenue from External Customer [Line Items]
Net Sales	$ 17.9			$ 20.0		$ 36.6	$ 45.8