Earnings per Share (EPS) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 27, 2020	Sep. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Earnings per Share [Abstract]
Net income attributable to Minerals Technologies Inc.	$ 28.3	$ 38.0	$ 81.3	$ 103.7
Weighted average shares outstanding (in shares)	34,100,000	35,000,000.0	34,200,000	35,100,000
Dilutive effect of stock options and stock units (in shares)	0	100,000	0	100,000
Weighted average shares outstanding, adjusted (in shares)	34,100,000	35,100,000	34,200,000	35,200,000
Basic earnings per share attributable to Minerals Technologies Inc. (in dollars per share)	$ 0.83	$ 1.09	$ 2.38	$ 2.95
Diluted earnings per share attributable to Minerals Technologies Inc. (in dollars per share)	$ 0.83	$ 1.08	$ 2.38	$ 2.95
Stock Options [Member]
Earnings per Share [Abstract]
Anti-dilutive securities not included in the weighted average commons shares outstanding calculation (in shares)	1,054,428	456,693	1,054,428	456,693