Income Taxes (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Income Tax Disclosure [Abstract]
Domestic	$ 56,905,000	$ 46,950,000	$ 49,484,000
Foreign	50,141,000	50,790,000	49,365,000
Income from operation before provision for taxes	107,046,000	97,740,000	98,849,000
Domestic [Abstract]
Taxes currently payable, Federal	14,838,000	11,793,000	12,287,000
Taxes currently payable, State and local	1,318,000	2,145,000	1,861,000
Deferred income taxes	3,236,000	(1,886,000)	411,000
Domestic tax provision (benefit)	19,392,000	12,052,000	14,559,000
Foreign [Abstract]
Taxes currently payable	13,364,000	12,297,000	13,043,000
Deferred income taxes	(1,979,000)	3,136,000	1,361,000
Foreign tax provision (benefit)	11,385,000	15,433,000	14,404,000
Total tax provision (benefit)	30,777,000	27,486,000	28,963,000
Reconciliation of U. S. federal statutory tax rate to effective tax rate [Abstract]
U.S. statutory tax rate (in hundredths)	35.00%	35.00%	35.00%
Depletion (in hundredths)	(3.90%)	(4.10%)	(3.80%)
Difference between tax provided on foreign earnings and the U.S. statutory rate (in hundredths)	(4.10%)	(1.00%)	(3.10%)
Change in Mexican law (in hundredths)	(0.50%)	(0.20%)	0.30%
State and local taxes, net of Federal tax benefit (in hundredths)	1.50%	1.20%	1.20%
Tax credits and foreign dividends (in hundredths)	(0.10%)	(0.10%)	(0.10%)
Decrease in valuation allowance (in hundredths)	(1.10%)	(1.20%)	(0.10%)
Impact of uncertain tax positions (in hundredths)	0.90%	(2.80%)	(1.50%)
Impact of officer's non-deductible compensation	2.10%	2.90%	1.20%
Other (in hundredths)	(1.10%)	(1.60%)	0.20%
Consolidated effective tax rate (in hundredths)	28.80%	28.10%	29.30%
Deferred tax assets [Abstract]
Accrued expenses	12,200,000	9,752,000
Net operating loss carry forwards	11,414,000	11,083,000
Pension and post-retirement benefits costs	43,828,000	40,584,000
Other	12,850,000	11,163,000
Valuation allowance	(5,666,000)	(6,860,000)
Total deferred tax assets	74,626,000	65,722,000
Deferred tax liabilities [Abstract]
Plant and equipment, principally due to differences in depreciation	10,333,000	4,832,000
Intangible assets	12,412,000	11,387,000
Mexican tax recapture	429,000	1,021,000
Other	3,983,000	4,067,000
Total deferred tax liabilities	27,157,000	21,307,000
Net deferred tax (assets) liabilities	47,469,000	44,415,000
Net deferred tax assets, current	6,253,000	4,903,000
Net deferred assets, long term	41,216,000	39,512,000
Operating Loss Carryforwards [Line Items]
Deferred tax assets arising from tax loss carry forwards which will be realized through future operations	7,200,000
Expiration period (in years)	20
Unrecognized tax benefits [Abstract]
Unrecognized tax benefits that would impact effective tax rate	3,100,000
Unrecognized tax benefits [Roll forward]
Balance as of beginning of year	3,912,000	6,473,000
Increases related to current year positions	696,000	563,000
Increases (decreases) related to new judgments	206,000	(373,000)
Decreases related to audit settlements and statute expirations	0	(2,751,000)
Balance as of end of year	4,814,000	3,912,000	6,473,000
Unrecognized tax benefits, net reversal of accrued interest and penalties	300,000
Unrecognized tax benefits, accrued interest and penalties	1,000,000
Cash paid for income taxes [Abstract]
Net cash paid for income taxes	21,500,000	31,900,000	24,900,000
Undistributed earnings of foreign subsidiaries [Abstract]
Foreign subsidiaries' undistributed earnings for which the company has not provided for withholding taxes	334,600,000
Estimated incremental taxes that may be incurred on foreign subsidiaries' undistributed earnings were the earnings to be repatriated	50,200,000
Indefinite lived tax loss carry forwards [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets arising from tax loss carry forwards which will be realized through future operations	4,300,000
Finite lived tax loss carry forwards [Member]
Operating Loss Carryforwards [Line Items]
Deferred tax assets arising from tax loss carry forwards which will be realized through future operations	$ 2,900,000