Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 04, 2021	Jun. 28, 2020	Jul. 04, 2021	Jun. 28, 2020
Earnings per Share [Abstract]
Net income attributable to Minerals Technologies Inc.	$ 41.9	$ 14.4	$ 81.8	$ 53.0
Weighted average shares outstanding (in shares)	33,700,000	34,100,000	33,800,000	34,200,000
Dilutive effect of stock options and stock units (in shares)	400,000	0	200,000	100,000
Weighted average shares outstanding, adjusted (in shares)	34,100,000	34,100,000	34,000,000.0	34,300,000
Basic earnings per share attributable to Minerals Technologies Inc. (in dollars per share)	$ 1.24	$ 0.42	$ 2.42	$ 1.55
Diluted earnings per share attributable to Minerals Technologies Inc. (in dollars per share)	$ 1.23	$ 0.42	$ 2.41	$ 1.55
Earnings per Share [Abstract]
Options outstanding (in shares)	1,415,684	1,448,699	1,415,684	1,448,699
Stock Options [Member]
Earnings per Share [Abstract]
Anti-dilutive securities not included in computation of diluted earnings per share (in shares)	253,895	1,448,699	253,895	1,448,699