Earnings (Loss) Per Share - Computation of Basic and Diluted Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Earnings (Loss) Per Share [Abstract]
Net income (loss) attributable to Minerals Technologies Inc. (in Dollars)	$ (18.4)	$ 167.1	$ 84.1
Weighted average shares outstanding (in Shares)	31.4	32.1	32.5
Dilutive effect of stock options and deferred restricted stock units (in Shares)	0.0	0.2	0.1
Weighted average shares outstanding, adjusted (in Shares)	31.4	32.3	32.6
Basic earnings (loss) per share attributable to MTI (in Dollars per share)	$ (0.59)	$ 5.21	$ 2.59
Diluted earnings (loss) per share attributable to MTI (in Dollars per share)	$ (0.59)	$ 5.17	$ 2.58