Earnings Per Share (EPS) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Dec. 31, 2016	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share (EPS) [Abstract]
Net income attributable to MTI	$ 75.8	$ 41.7	$ 43.0	$ 34.6	$ 36.7	$ 41.6	$ 21.2	$ 33.9	$ 195.1	$ 133.4	$ 107.9
Weighted average shares outstanding (in shares)									35,200,000	34,900,000	34,700,000
Dilutive effect of stock options and stock units (in shares)									400,000	300,000	300,000
Weighted average shares outstanding, adjusted (in shares)									35,600,000	35,200,000	35,000,000
Basic earnings per share attributable to MTI (in dollars per share)	$ 2.14	$ 1.18	$ 1.23	$ 0.99	$ 1.05	$ 1.19	$ 0.61	$ 0.97	$ 5.54	$ 3.82	$ 3.11
Diluted earnings per share attributable to MTI (in dollars per share)	$ 2.12	$ 1.17	$ 1.21	$ 0.97	$ 1.04	$ 1.18	$ 0.60	$ 0.97	$ 5.48	$ 3.79	$ 3.08
Stock Options [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities not included in the weighted average commons shares outstanding calculation (in shares)									181,003	784	386,766