Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Disclosure [Abstract]
ProvisionalIncomeTaxExpenseRelatedtoTaxCutsandJobsAct	$ 28,840
ProvisionalTaxExpenseRelatedtoDeferredTaxBalances	22,640
ProvisionalTaxExpenseRelatedtoDeferredTaxBalancesPreviouslyRecordedThroughAOCI	43,515
ProvisionalTaxBenefitRelatedtoDeferredTaxBalancesPreviouslyRecordedThroughProvisionforIncomeTaxes	20,875
ProvisionalOneTimeTransitionIncomeTaxExpense	6,200
ProvisionalOneTimeTransitionTaxCurrentLiability	1,174
ProvisionalOneTimeTransitionTaxNonCurrentLiability	5,026
ProvisionalFederalCurrentIncomeTaxExpenseRelatedtoOneTimeTransitionTax	5,067
ProvisionalStateCurrentIncomeTaxExpenseRelatedtoOneTimeTransitionTax	1,133
Unrecognized tax benefits	2,318	$ 1,755	$ 2,247
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1:	1,755	2,247	3,104
Additions based on tax positions related to current year	437	397	464
Additions based on tax positions of prior years	291	0	0
Reductions for tax positions of prior years	(165)	(889)	(252)
Settlements	0	0	(1,069)
Balance at December 31:	2,318	1,755	$ 2,247
Accrued interest and penalties	$ 983	$ 650
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Statutory federal tax rate	35.00%	35.00%	35.00%
State and local income taxes, net of federal benefit	4.00%	3.30%	3.80%
Deemed repatriation of foreign earnings	3.30%	0.00%	0.00%
Effect of tax rate changes	13.50%	0.00%	0.00%
Other, net	1.30%	0.90%	1.20%
Effective tax rate	57.10%	39.20%	40.00%
Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest [Abstract]
Income before Income Taxes, Domestic	$ 155,268	$ 143,567	$ 143,144
Income before Income Taxes, Foreign	12,280	9,932	9,197
Income before Provision for Income Taxes	167,548	153,499	152,341
Provisions for Income Taxes Recorded in the Consolidated Statements of Income [Abstract]
U.S. Federal, current expense	66,475	33,030	46,174
State, current expense	11,396	4,821	7,996
Foreign, current expense	3,574	2,795	2,666
Total current expense	81,445	40,646	56,836
U.S. Federal, deferred expense	15,332	16,676	3,224
State, deferred expense	(1,139)	3,008	958
Foreign, deferred expense	(25)	(144)	(9)
Total deferred (benefit) expense	14,168	19,540	4,173
Total income tax provision	95,613	60,186	$ 61,009
Components of Deferred Tax Assets and Liabilities [Abstract]
Postretirement benefits	19,768	29,788
Payroll accruals	1,866	2,618
Bad debt reserves	1,023	1,322
Other deferred tax assets	4,772	5,251
Pension	37,988	47,847
Inventory	12,123	11,336
Subtotal	77,540	98,162
less: valuation allowances	(23)	(136)
Deferred tax assets	77,517	98,026
Fixed assets	(27,156)	(40,887)
Computer software	(3,240)	(5,724)
Other deferred tax liabilities	(2,622)	(3,043)
Deferred tax liabilities	(33,018)	(49,654)
Net deferred tax assets	44,499	48,372
Deferred Tax Assets, Net, Classification [Abstract]
Deferred tax assets, included in other non-current assets	44,860	48,666
Deferred tax liabilities included in other current liabilities	(361)	(294)
Deferred Tax Assets, Operating Loss Carryforwards, Components [Abstract]
Foreign net operating losses	187	239
State net operating losses	$ 504	$ 529