Earnings Per Share (EPS) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jul. 01, 2012	Apr. 01, 2012	Dec. 31, 2011	Oct. 02, 2011	Jul. 03, 2011	Apr. 03, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Basic EPS [Abstract]
Net income (loss) attributable to MTI	$ 17,700	$ 18,600	$ 19,700	$ 18,000	$ 19,600	$ 15,700	$ 16,400	$ 15,800	$ 74,147	$ 67,521	$ 66,869
Weighted average shares outstanding (in shares)									35,340,000	36,018,000	37,228,000
Basic earnings (loss) per share attributable to MTI (in dollars per share)	$ 0.50	$ 0.53	$ 0.56	$ 0.51	$ 0.55	$ 0.44	$ 0.45	$ 0.43	$ 2.10	$ 1.87	$ 1.80
Diluted EPS [Abstract]
Net income (loss) attributable to MTI	$ 17,700	$ 18,600	$ 19,700	$ 18,000	$ 19,600	$ 15,700	$ 16,400	$ 15,800	$ 74,147	$ 67,521	$ 66,869
Weighted average shares outstanding (in shares)									35,340,000	36,018,000	37,228,000
Dilutive effect of stock options (in shares)									189,000	218,000	158,000
Weighted average shares outstanding, adjusted (in shares)									35,529,000	36,236,000	37,386,000
Diluted earnings (loss) per share attributable to MTI (in dollars per share)	$ 0.50	$ 0.53	$ 0.56	$ 0.51	$ 0.55	$ 0.43	$ 0.45	$ 0.43	$ 2.09	$ 1.86	$ 1.79
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)									2,404	218,064	193,602