Segment and Related Information (Sales by Product Category) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jul. 01, 2012	Apr. 01, 2012	Dec. 31, 2011	Oct. 02, 2011	Jul. 03, 2011	Apr. 03, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenue from External Customer [Line Items]
Net sales	$ 244,200	$ 250,300	$ 254,000	$ 257,100	$ 251,700	$ 262,200	$ 268,400	$ 262,500	$ 1,005,619	$ 1,044,853	$ 1,002,354
Paper PCC [Member]
Revenue from External Customer [Line Items]
Net sales									480,300	497,000	496,600
Specialty PCC [Member]
Revenue from External Customer [Line Items]
Net sales									65,900	63,600	58,000
Talc [Member]
Revenue from External Customer [Line Items]
Net sales									48,100	46,900	44,000
Ground Calcium Carbonate [Member]
Revenue from External Customer [Line Items]
Net sales									67,900	68,600	66,400
Refractory Products [Member]
Revenue from External Customer [Line Items]
Net sales									264,100	287,400	264,500
Metallurgical Products [Member]
Revenue from External Customer [Line Items]
Net sales									$ 79,300	$ 81,400	$ 72,900