Segment and Related Information, Sales By Product Category (Details) - USD ($) $ in Millions	3 Months Ended					12 Months Ended
	Apr. 02, 2017	Dec. 31, 2016	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2016
Revenue from External Customer [Line Items]
Net Sales	$ 405.0				$ 410.2
Paper PCC [Member]
Revenue from External Customer [Line Items]
Net Sales	93.4				103.2
Specialty PCC [Member]
Revenue from External Customer [Line Items]
Net Sales	17.0				16.7
Talc [Member]
Revenue from External Customer [Line Items]
Net Sales	14.3				15.0
Ground Calcium Carbonate [Member]
Revenue from External Customer [Line Items]
Net Sales	21.5				20.7
Refractory Products [Member]
Revenue from External Customer [Line Items]
Net Sales	56.7				53.4
Metallurgical Products [Member]
Revenue from External Customer [Line Items]
Net Sales	13.5				15.8
Metalcasting [Member]
Revenue from External Customer [Line Items]
Net Sales	66.6	$ 66.9	$ 63.1	$ 68.0	60.0	$ 258.0
Household, Personal Care and Specialty Products [Member]
Revenue from External Customer [Line Items]
Net Sales	41.1	39.8	42.1	44.0	45.3	171.2
Environmental Products [Member]
Revenue from External Customer [Line Items]
Net Sales	10.6	14.4	24.6	26.5	13.4	78.9
Building Materials [Member]
Revenue from External Customer [Line Items]
Net Sales	17.4	17.1	16.9	19.7	20.4	74.1
Basic Minerals [Member]
Revenue from External Customer [Line Items]
Net Sales	34.2	$ 36.8	$ 22.3	$ 24.3	20.5	$ 103.9
Energy Services [Member]
Revenue from External Customer [Line Items]
Net Sales	$ 18.7				$ 25.8