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Income Taxes Income Tax Rate Reconciliation (Details)	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Sep. 30, 2017
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	24.50%	35.00%
Adjustments to reconcile to the effective tax rate:
State income taxes, net of federal benefit	3.30%	4.30%
Valuation allowance adjustment related to stock compensation	0.00%	(5.70%)
Tax benefits from stock compensation	(1.30%)	2.80%
U.S. manufacturing deduction	0.00%	1.60%
Tax credits	(0.40%)	0.90%
Effective Income Tax Rate Reconciliation, GILTI, percent	(0.10%)	0.00%
Other	0.30%	0.50%
Walter Energy accrual	(5.80%)	0.00%
Change in rate for deferred taxes	2.10%	(278.40%)
Effective income tax rate	21.90%	(260.10%)

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Effective Income Tax Rate Reconciliation, GILTI, percent

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

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