Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Oct. 03, 2021	Sep. 27, 2020	Oct. 03, 2021	Sep. 27, 2020
Earnings per Share [Abstract]
Net income attributable to Minerals Technologies Inc.	$ 41.4	$ 28.3	$ 123.2	$ 81.3
Weighted average shares outstanding (in shares)	33,500,000	34,100,000	33,700,000	34,200,000
Dilutive effect of stock options and stock units (in shares)	300,000	0	200,000	0
Weighted average shares outstanding, adjusted (in shares)	33,800,000	34,100,000	33,900,000	34,200,000
Basic earnings per share attributable to Minerals Technologies Inc. (in dollars per share)	$ 1.24	$ 0.83	$ 3.66	$ 2.38
Diluted earnings per share attributable to Minerals Technologies Inc. (in dollars per share)	$ 1.22	$ 0.83	$ 3.63	$ 2.38
Earnings per Share [Abstract]
Options outstanding (in shares)	1,409,110	1,439,677	1,409,110	1,439,677
Stock Options [Member]
Earnings per Share [Abstract]
Anti-dilutive securities not included in computation of diluted earnings per share (in shares)	526,956	1,054,428	526,956	1,054,428