Quarterly Financial Data (unaudited) (Details) (USD $)	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	$ 244,200,000	$ 250,300,000	$ 254,000,000	$ 257,100,000	$ 251,700,000	$ 262,200,000	$ 268,400,000	$ 262,500,000	$ 1,005,619,000	$ 1,044,853,000	$ 1,002,354,000
Gross profit	53,100,000	55,000,000	56,300,000	54,900,000	52,700,000	52,900,000	53,700,000	52,900,000	219,374,000	212,196,000	209,193,000
Income from operations	25,700,000	27,800,000	29,500,000	27,000,000	25,200,000	25,400,000	25,100,000	24,700,000	110,041,000	100,338,000	98,277,000
Income from continuing operations, net of tax	18,200,000	19,200,000	20,200,000	18,600,000	20,100,000	16,300,000	17,200,000	16,700,000
Noncontrolling interests	(500,000)	(600,000)	(500,000)	(600,000)	(400,000)	(700,000)	(700,000)	(900,000)	2,122,000	2,733,000	3,017,000
Net income (loss) attributable to MTI	17,700,000	18,600,000	19,700,000	18,000,000	19,600,000	15,700,000	16,400,000	15,800,000	74,147,000	67,521,000	66,869,000
Basic [Abstract]
Basic earnings (loss) per share attributable to MTI (in dollars per share)	$ 0.50	$ 0.53	$ 0.56	$ 0.51	$ 0.55	$ 0.44	$ 0.45	$ 0.43	$ 2.10	$ 1.87	$ 1.80
Diluted [Abstract]
Diluted earnings (loss) per share attributable to MTI (in dollars per share)	$ 0.50	$ 0.53	$ 0.56	$ 0.51	$ 0.55	$ 0.43	$ 0.45	$ 0.43	$ 2.09	$ 1.86	$ 1.79
Market price range per share of common stock [Abstract]
High (in dollars per share)	$ 39.92	$ 36.99	$ 33.60	$ 33.96	$ 29.00	$ 34.32	$ 35.05	$ 34.37
Low (in dollars per share)	$ 34.25	$ 30.50	$ 30.81	$ 28.78	$ 23.38	$ 24.64	$ 31.51	$ 31.23
Close (in dollars per share)	$ 39.92	$ 35.46	$ 31.89	$ 32.70	$ 28.27	$ 24.64	$ 33.83	$ 34.37	$ 39.92	$ 28.27
Dividends paid per common share (in dollars per share)	$ 0.05	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.025	$ 0.125
PCC [Member]
Revenue from External Customer [Line Items]
Net sales	134,900,000	137,000,000	136,300,000	138,100,000	133,100,000	142,500,000	140,200,000	144,800,000
Processed Minerals [Member]
Revenue from External Customer [Line Items]
Net sales	25,900,000	28,600,000	31,800,000	29,600,000	26,800,000	28,600,000	31,600,000	28,500,000
Specialty Minerals [Member]
Revenue from External Customer [Line Items]
Net sales	160,800,000	165,600,000	168,100,000	167,700,000	159,900,000	171,100,000	171,800,000	173,300,000	662,200,000	676,100,000	665,000,000
Refractories [Member]
Revenue from External Customer [Line Items]
Net sales	$ 83,400,000	$ 84,700,000	$ 85,900,000	$ 89,400,000	$ 91,800,000	$ 91,100,000	$ 96,600,000	$ 89,200,000	$ 343,400,000	$ 368,800,000	$ 337,400,000