Quarterly Financial Data (unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 27, 2015	Jun. 28, 2015	Mar. 29, 2015	Dec. 31, 2014	Sep. 28, 2014	Jun. 29, 2014	Mar. 30, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue from External Customer [Line Items]
Net sales	$ 429.9	$ 451.0	$ 463.4	$ 453.3	$ 516.0	$ 543.5	$ 421.1	$ 244.4	$ 1,797.6	$ 1,725.0	$ 1,018.2
Gross profit	109.3	118.9	126.2	116.6	132.4	145.0	102.7	55.3	471.0	435.4	233.7
Income from operations	37.7	49.9	52.8	59.9	42.6	66.8	35.8	23.6	200.3	168.8	126.9
Income from continuing operations	17.8	30.3	27.5	36.0	21.9	37.6	17.6	16.3	107.9	90.3	86.1
Income (loss) from discontinued operations, net of tax					0.1	0.2	1.8	0.0	0.0	2.1	(5.8)
Net income attributable to MTI	$ 17.0	$ 29.2	$ 26.6	$ 35.1	$ 21.3	$ 37.0	$ 18.5	$ 15.6	$ 107.9	$ 92.4	$ 80.3
Basic earnings per share attributable to MTI shareholders [Abstract]
Income from continuing operations attributable to MTI (in dollars per share)	$ 0.49	$ 0.84	$ 0.77	$ 1.01	$ 0.61	$ 1.07	$ 0.48	$ 0.45	$ 3.11	$ 2.62	$ 2.48
Income (loss) from discontinued operations attributable to MTI (in dollars per share)	0	0	0	0	0.01	0	0.05	0	0	0.06	(0.17)
Net income (in dollars per share)	0.49	0.84	0.77	1.01	0.62	1.07	0.53	0.45	3.11	2.68	2.31
Diluted earnings per share attributable to MTI shareholders [Abstract]
Income from continuing operations attributable to MTI (in dollars per share)	0.48	0.83	0.76	1.01	0.61	1.06	0.48	0.45	3.08	2.59	2.46
Loss from discontinued operations attributable to MTI (in dollars per share)	0	0	0	0	0	0	0.05	0	0	0.06	(0.16)
Net Income attributable to MTI common shareholders (in dollars per share)	0.48	0.83	0.76	1.01	0.61	1.06	0.53	0.45	3.08	2.65	$ 2.30
Market price range per share of common stock [Abstract]
High (in dollars per share)	61.80	68.15	74.21	74.74	77.40	67.02	66.50	64.48
Low (in dollars per share)	45.35	46.69	66.49	59.00	58.06	57.14	59.49	48.81
Close (in dollars per share)	45.86	50.31	69.02	70.65	69.45	63.45	65.01	63.57	45.86	$ 69.45
Dividends paid per common share (in dollars per share)	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.05	$ 0.20
Specialty Minerals [Member]
Revenue from External Customer [Line Items]
Net sales	$ 157.6	$ 156.5	$ 156.5	$ 154.0	$ 159.6	$ 163.0	$ 167.8	$ 159.7
Refractories [Member]
Revenue from External Customer [Line Items]
Net sales	68.2	77.4	76.4	73.9	92.9	90.4	91.7	84.7
Performance Materials [Member]
Revenue from External Customer [Line Items]
Net sales	131.3	126.5	129.1	127.9	141.4	135.6	75.8	0.0
Construction Technologies [Member]
Revenue from External Customer [Line Items]
Net sales	39.4	49.7	52.1	38.9	46.0	69.1	37.2	0.0
Energy Services [Member]
Revenue from External Customer [Line Items]
Net sales	$ 33.4	$ 40.9	$ 49.3	$ 58.6	$ 76.1	$ 85.4	$ 48.6	$ 0.0