Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Apr. 04, 2021	Mar. 29, 2020
Earnings per Share [Abstract]
Net income attributable to Minerals Technologies Inc.	$ 39.9	$ 38.6
Weighted average shares outstanding (in shares)	33,800,000	34,400,000
Dilutive effect of stock options and stock units (in shares)	200,000	0
Weighted average shares outstanding, adjusted (in shares)	34,000,000.0	34,400,000
Basic earnings per share attributable to Minerals Technologies Inc. (in dollars per share)	$ 1.18	$ 1.12
Diluted earnings per share attributable to Minerals Technologies Inc. (in dollars per share)	$ 1.17	$ 1.12
Earnings per Share [Abstract]
Options outstanding (in shares)	1,499,373	1,492,819
Stock Options [Member]
Earnings per Share [Abstract]
Anti-dilutive securities not included in computation of diluted earnings per share (in shares)	558,734	1,181,945