Segment and Related Information, Sales By Product Category (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 28, 2015	Jun. 29, 2014	Jun. 28, 2015	Jun. 29, 2014
Revenue from External Customer [Line Items]
Total net sales	$ 463.4	$ 421.1	$ 916.7	$ 665.5
Paper PCC [Member]
Revenue from External Customer [Line Items]
Total net sales	104.7	115.2	209.9	227.9
Specialty PCC [Member]
Revenue from External Customer [Line Items]
Total net sales	16.2	17.9	32.7	34.2
Talc [Member]
Revenue from External Customer [Line Items]
Total net sales	14.2	14.4	28.0	27.9
Ground Calcium Carbonate [Member]
Revenue from External Customer [Line Items]
Total net sales	21.4	20.4	39.9	37.5
Refractory Products [Member]
Revenue from External Customer [Line Items]
Total net sales	59.5	68.5	117.8	131.7
Metallurgical Products [Member]
Revenue from External Customer [Line Items]
Total net sales	16.9	23.1	32.5	44.7
Metalcasting [Member]
Revenue from External Customer [Line Items]
Total net sales	71.6	39.4	136.8	39.4
Household, Personal Care and Specialty Products [Member]
Revenue from External Customer [Line Items]
Total net sales	41.7	23.4	83.5	23.4
Basic Minerals and Other Products [Member]
Revenue from External Customer [Line Items]
Total net sales	15.8	13.0	36.7	13.0
Environmental Products [Member]
Revenue from External Customer [Line Items]
Total net sales	22.1	17.3	33.5	17.3
Building Materials and Other Products [Member]
Revenue from External Customer [Line Items]
Total net sales	30.0	19.9	57.5	19.9
Energy Services [Member]
Revenue from External Customer [Line Items]
Total net sales	$ 49.3	$ 48.6	$ 107.9	$ 48.6