Segment and Related Information, Sales By Product Category (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 30, 2014	Mar. 31, 2013
Revenue from External Customer [Line Items]
Net sales	$ 244,396	$ 250,513
Paper PCC [Member]
Revenue from External Customer [Line Items]
Net sales	112,800	120,500
Specialty PCC [Member]
Revenue from External Customer [Line Items]
Net sales	16,300	16,800
Talc [Member]
Revenue from External Customer [Line Items]
Net sales	13,400	12,400
Ground Calcium Carbonate [Member]
Revenue from External Customer [Line Items]
Net sales	17,200	17,200
Refractory Products [Member]
Revenue from External Customer [Line Items]
Net sales	63,100	62,400
Metallurgical Products [Member]
Revenue from External Customer [Line Items]
Net sales	$ 21,600	$ 21,200