CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 454,331	$ 454,092
Short-term investments, at cost which approximates market	15,586	14,178
Accounts receivable, net	197,834	193,328
Inventories	88,755	84,569
Prepaid expenses and other current assets	18,364	18,318
Total current assets	774,870	764,485
Property, plant and equipment, less accumulated depreciation and depletion - March 31, 2013 - $943,676; December 31,2012 - $944,283	312,436	317,669
Goodwill	65,081	65,829
Other assets and deferred charges	58,732	63,206
Total assets	1,211,119	1,211,189
Current liabilities:
Short-term debt	7,226	7,111
Current maturities of long-term debt	77,260	76,977
Accounts payable	109,857	98,371
Other current liabilities	55,785	67,639
Total current liabilities	250,128	250,098
Long-term debt	8,200	8,478
Accrued Pension and Post-Retirement Benefits	108,719	108,035
Other non-current liabilities	31,313	30,859
Total liabilities	398,360	397,470
Shareholders' equity:
Common stock	4,717	4,700
Additional paid-in capital	349,470	345,929
Retained earnings	1,049,870	1,032,869
Accumulated other comprehensive loss	(63,162)	(51,198)
Less common stock held in treasury	(551,337)	(541,889)
Total MTI shareholders' equity	789,558	790,411
Non-controlling interest	23,201	23,308
Total shareholders' equity	812,759	813,719
Total liabilities and shareholders' equity	$ 1,211,119	$ 1,211,189