CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Oct. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Statements of Income [Abstract]
Total net sales	$ 464.1	$ 424.4	$ 1,360.1	$ 1,243.5
Total cost of sales	344.9	305.2	1,011.5	890.9
Production margin	119.2	119.2	348.6	352.6
Marketing and administrative expenses	45.4	45.2	135.1	132.8
Research and development expenses	5.0	5.9	17.5	17.8
Acquisition-related transaction and integration costs	0.3	0.5	1.7	2.8
Restructuring and other items, net	0.3	0.4	0.7	0.9
Income from operations	68.2	67.2	193.6	198.3
Interest expense, net	(11.7)	(10.5)	(33.9)	(32.5)
Debt modification costs and fees	0.0	0.0	0.0	(3.9)
Pension settlement costs	(3.6)	0.0	(3.6)	0.0
Other non-operating deductions, net	(0.9)	(2.1)	(0.5)	(4.7)
Total non-operating deductions, net	(16.2)	(12.6)	(38.0)	(41.1)
Income before provision for taxes and equity in earnings	52.0	54.6	155.6	157.2
Provision for taxes on income	9.7	12.1	29.3	35.6
Equity in earnings of affiliates, net of tax	0.6	0.4	2.9	0.7
Consolidated net income	42.9	42.9	129.2	122.3
Less: Net income attributable to non-controlling interests	1.0	1.2	3.3	3.0
Net income attributable to Minerals Technologies Inc. (MTI)	$ 41.9	$ 41.7	$ 125.9	$ 119.3
Basic:
Income from continuing operations attributable to MTI (in dollars per share)	$ 1.19	$ 1.18	$ 3.57	$ 3.40
Diluted:
Income from continuing operations attributable to MTI (in dollars per share)	1.18	1.17	3.54	3.35
Cash dividends declared per common share (in dollars per share)	$ 0.05	$ 0.05	$ 0.15	$ 0.15
Shares used in computation of earnings per share:
Basic (in shares)	35.3	35.3	35.3	35.1
Diluted (in shares)	35.6	35.6	35.6	35.6
Product [Member]
Statements of Income [Abstract]
Total net sales	$ 444.9	$ 405.4	$ 1,302.1	$ 1,187.9
Total cost of sales	332.1	293.0	972.4	854.7
Service [Member]
Statements of Income [Abstract]
Total net sales	19.2	19.0	58.0	55.6
Total cost of sales	$ 12.8	$ 12.2	$ 39.1	$ 36.2