Quarterly Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 29, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jul. 01, 2018	Apr. 01, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from External Customer [Abstract]
Net sales	$ 440.2	$ 449.3	$ 463.8	$ 437.7	$ 447.5	$ 464.1	$ 464.7	$ 431.3	$ 1,791.0	$ 1,807.6	$ 1,675.7
Gross profit	107.7	111.2	112.0	109.7	112.8	119.2	115.9	113.5	440.6	461.4	467.2
Income from operations	47.7	53.5	45.5	62.0	62.3	68.2	62.8	62.6	208.7	255.9	244.4
Consolidated net income	29.6	39.1	27.6	40.0	44.0	42.9	45.2	41.1	136.4	173.2	199.0
Net income attributable to Minerals Technologies Inc. (MTI)	$ 29.0	$ 38.0	$ 26.6	$ 39.1	$ 43.1	$ 41.9	$ 44.1	$ 39.9	$ 132.7	$ 169.0	$ 195.1
Basic earnings per share attributable to MTI shareholders (in dollars per share)	$ 0.83	$ 1.09	$ 0.76	$ 1.11	$ 1.22	$ 1.19	$ 1.25	$ 1.13	$ 3.79	$ 4.79	$ 5.54
Diluted earnings per share attributable to MTI shareholders (in dollars per share)	0.83	1.08	0.75	1.11	1.22	1.18	1.24	1.12	3.78	4.75	$ 5.48
Market price range per share of common stock [Abstract]
High (in dollars per share)	58.12	55.33	63.20	61.01	67.65	77.75	76.40	76.95
Low (in dollars per share)	48.92	45.55	51.78	49.47	47.89	65.75	65.10	66.10
Close (in dollars per share)	57.63	52.77	53.51	58.79	51.34	67.60	75.35	66.95	57.63	$ 51.34
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	$ 201.4	$ 207.3	$ 215.4	$ 199.2	$ 206.8	$ 219.5	$ 214.5	$ 187.3	$ 823.3	$ 828.1	$ 734.8
Specialty Minerals [Member]
Revenue from External Customer [Abstract]
Net sales	141.8	143.1	145.1	144.4	142.5	146.3	150.9	149.6	574.4	589.3	584.8
Refractories [Member]
Revenue from External Customer [Abstract]
Net sales	73.4	73.4	77.5	73.8	77.9	79.1	79.6	75.3	298.1	311.9	279.4
Energy Services [Member]
Revenue from External Customer [Abstract]
Net sales	$ 23.6	$ 25.5	$ 25.8	$ 20.3	$ 20.3	$ 19.2	$ 19.7	$ 19.1	$ 95.2	$ 78.3	$ 76.7