CONDENSED CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 01, 2018	Jul. 02, 2017	Jul. 01, 2018	Jul. 02, 2017
Statements of Income [Abstract]
Total net sales	$ 464.7	$ 414.1	$ 896.0	$ 819.1
Total cost of sales	348.8	294.4	666.6	585.7
Production margin	115.9	119.7	229.4	233.4
Marketing and administrative expenses	45.3	43.6	89.7	87.6
Research and development expenses	6.4	6.1	12.5	11.9
Acquisition-related transaction and integration costs	1.0	0.8	1.4	2.3
Restructuring and other items, net	0.4	0.2	0.4	0.5
Income from operations	62.8	69.0	125.4	131.1
Interest expense, net	(11.5)	(10.2)	(22.2)	(22.0)
Debt modification costs and fees	0.0	0.0	0.0	(3.9)
Other non-operating income (deductions), net	3.1	(1.7)	0.4	(2.6)
Total non-operating deductions, net	(8.4)	(11.9)	(21.8)	(28.5)
Income from continuing operations before provision for taxes and equity in earnings	54.4	57.1	103.6	102.6
Provision for taxes on income	10.3	13.4	19.6	23.5
Equity in earnings of affiliates, net of tax	1.1	0.1	2.3	0.3
Consolidated net income	45.2	43.8	86.3	79.4
Less: Net income attributable to non-controlling interests	1.1	0.8	2.3	1.8
Net income attributable to Minerals Technologies Inc. (MTI)	$ 44.1	$ 43.0	$ 84.0	$ 77.6
Basic:
Income from continuing operations attributable to MTI (in dollars per share)	$ 1.25	$ 1.23	$ 2.37	$ 2.21
Diluted:
Income from continuing operations attributable to MTI (in dollars per share)	1.24	1.21	2.36	2.18
Cash dividends declared per common share (in dollars per share)	$ 0.05	$ 0.05	$ 0.10	$ 0.10
Shares used in computation of earnings per share:
Basic (in shares)	35.3	35.1	35.4	35.1
Diluted (in shares)	35.6	35.6	35.6	35.6
Product [Member]
Statements of Income [Abstract]
Total net sales	$ 445.0	$ 396.2	$ 857.2	$ 782.5
Total cost of sales	335.3	282.7	640.3	561.7
Service [Member]
Statements of Income [Abstract]
Total net sales	19.7	17.9	38.8	36.6
Total cost of sales	$ 13.5	$ 11.7	$ 26.3	$ 24.0