Quarterly Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue from External Customer [Abstract]
Net sales	$ 447.5	$ 464.1	$ 464.7	$ 431.3	$ 432.1	$ 424.5	$ 414.1	$ 405.0	$ 1,807.6	$ 1,675.7	$ 1,638.0
Gross profit	112.8	119.2	115.9	113.5	114.5	119.3	119.7	113.7	461.4	467.2	460.4
Income from operations	62.3	68.2	62.8	62.6	46.1	67.2	69.0	62.1	255.9	244.4	223.9
Consolidated net income	44.0	42.9	45.2	41.1	76.7	42.8	43.8	35.6	173.2	199.0	137.1
Net income attributable to Minerals Technologies Inc. (MTI)	$ 43.1	$ 41.9	$ 44.1	$ 39.9	$ 75.8	$ 41.7	$ 43.0	$ 34.6	$ 169.0	$ 195.1	$ 133.4
Basic earnings per share attributable to MTI (in dollars per share)	$ 1.22	$ 1.19	$ 1.25	$ 1.13	$ 2.14	$ 1.18	$ 1.23	$ 0.99	$ 4.79	$ 5.54	$ 3.82
Diluted earnings per share attributable to MTI shareholders (in dollars per share)	1.22	1.18	1.24	1.12	2.12	1.17	1.21	0.97	4.75	5.48	$ 3.79
Market price range per share of common stock [Abstract]
High (in dollars per share)	67.65	77.75	76.40	76.95	73.55	75.60	80.20	83.70
Low (in dollars per share)	47.89	65.75	65.10	66.10	66.40	62.95	70.50	72.20
Close (in dollars per share)	51.34	67.60	75.35	66.95	68.85	70.65	73.20	76.60	51.34	$ 68.85
Dividends paid per common share (in dollars per share)	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.20
Performance Materials [Member]
Revenue from External Customer [Abstract]
Net sales	$ 206.8	$ 219.5	$ 214.5	$ 187.3	$ 195.8	$ 188.8	$ 180.3	$ 169.9	$ 828.1	$ 734.8	$ 686.1
Specialty Minerals [Member]
Revenue from External Customer [Abstract]
Net sales	142.5	146.3	150.9	149.6	143.9	147.7	147.0	146.2	589.3	584.8	591.5
Refractories [Member]
Revenue from External Customer [Abstract]
Net sales	77.9	79.1	79.6	75.3	71.3	69.0	68.9	70.2	311.9	279.4	274.5
Energy Services [Member]
Revenue from External Customer [Abstract]
Net sales	$ 20.3	$ 19.2	$ 19.7	$ 19.1	$ 21.1	$ 19.0	$ 17.9	$ 18.7	$ 78.3	$ 76.7	$ 85.9