Earnings per Share (EPS) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 29, 2019	Sep. 30, 2018	Sep. 29, 2019	Sep. 30, 2018
Earnings per Share (EPS) [Abstract]
Net income attributable to Minerals Technologies Inc.	$ 38.0	$ 41.9	$ 103.7	$ 125.9
Weighted average shares outstanding (in shares)	35,000,000.0	35,300,000	35,100,000	35,300,000
Dilutive effect of stock options and stock units (in shares)	100,000	300,000	100,000	300,000
Weighted average shares outstanding, adjusted (in shares)	35,100,000	35,600,000	35,200,000	35,600,000
Basic earnings per share attributable to Minerals Technologies Inc. (in dollars per share)	$ 1.09	$ 1.19	$ 2.95	$ 3.57
Diluted earnings per share attributable to Minerals Technologies Inc. (in dollars per share)	$ 1.08	$ 1.18	$ 2.95	$ 3.54
Stock Options [Member]
Antidilutive Securities Excluded from Earnings Per Share Calculation [Abstract]
Anti-dilutive securities not included in the weighted average commons shares outstanding calculation (in shares)	456,693	352,625	456,693	352,625