CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statements of Income [Abstract]
Total net sales	$ 1,594.8	$ 1,791.0	$ 1,807.6
Total cost of sales	1,189.4	1,350.4	1,346.2
Production margin	405.4	440.6	461.4
Marketing and administrative expenses	176.5	187.5	178.6
Research and development expenses	19.9	20.3	22.7
Litigation expenses	10.4	10.9	0.0
Acquisition-related expenses	3.1	0.0	1.7
Restructuring and other items, net	7.6	13.2	2.5
Income from operations	187.9	208.7	255.9
Interest expense, net	(38.2)	(43.2)	(45.9)
Non-cash pension settlement charge	(6.4)	0.0	(4.4)
Other non-operating income (deductions), net	(5.3)	(8.2)	(1.5)
Total non-operating deductions, net	(49.9)	(51.4)	(51.8)
Income from operations before tax and equity in earnings	138.0	157.3	204.1
Provision for taxes on income	24.4	22.8	34.4
Equity in earnings of affiliates, net of tax	2.2	1.9	3.5
Consolidated net income	115.8	136.4	173.2
Less: Net income attributable to non-controlling interests	3.4	3.7	4.2
Net income attributable to Minerals Technologies Inc. (MTI)	$ 112.4	$ 132.7	$ 169.0
Basic:
Income from operations attributable to MTI (in dollars per share)	$ 3.29	$ 3.79	$ 4.79
Diluted:
Income from operations attributable to MTI (in dollars per share)	3.29	3.78	4.75
Cash dividends declared per common share (in dollars per share)	$ 0.20	$ 0.20	$ 0.20
Shares used in computation of earnings per share:
Basic (in shares)	34.2	35.0	35.3
Diluted (in shares)	34.2	35.1	35.6
Product [Member]
Statements of Income [Abstract]
Total net sales	$ 1,521.8	$ 1,695.8	$ 1,729.3
Total cost of sales	1,140.5	1,285.8	1,293.3
Service [Member]
Statements of Income [Abstract]
Total net sales	73.0	95.2	78.3
Total cost of sales	$ 48.9	$ 64.6	$ 52.9