Income Taxes [Line Items]

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- Definition

Amount of decrease reasonably possible in the next twelve months for the unrecognized tax benefit.

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- Definition

Amount before allocation of valuation allowances of deferred tax asset attributable to deductible alternative minimum tax credit carryforwards.

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- Definition

Amount of deferred tax liability attributable to taxable temporary differences from capitalized costs.

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- Definition

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

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- Definition

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

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to increase (decrease) in the income tax rates.

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- Definition

Tax year that remains open to examination under enacted tax laws, in CCYY format.

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Income Taxes (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
Income Taxes (Details) - USD ($) $ in Millions	Jan. 01, 2018	Dec. 31, 2017	Jan. 01, 2017	Sep. 30, 2018	Oct. 01, 2017
Income Taxes [Line Items]
Provision for (benefit from) income taxes		$ (13.6)	$ 9.1
Benefit from change in tax rate		24.2
U.S. statutory rate					35.00%
Re-measurement of certain deferred tax liabilities		12.4
Alternative minimum tax credits		11.8
Unrecognized tax benefit that would impact effective tax rate within next twelve months		$ 23.3
Minimum \| Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax years by major tax jurisdiction		2007
Maximum \| Internal Revenue Service (IRS)
Income Taxes [Line Items]
Open tax years by major tax jurisdiction		2016
Forecast
Income Taxes [Line Items]
U.S. statutory rate	24.50%			21.00%