Income Taxes (Details) - USD ($)	3 Months Ended	9 Months Ended	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Effective tax rate (in hundredths)	18.50%	22.90%	19.60%	25.30%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent	35.00%	21.00%	21.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Tax Settlement, Domestic, Amount			$ 1,300,000
Effective Income Tax Rate Reconciliation, Other Adjustments, Percent			0.20%
Minimum [Member]
Significant change in unrecognized tax benefits is reasonably possible, estimated range of change, lower bound	$ 0		$ 0
Maximum [Member]
Significant change in unrecognized tax benefits is reasonably possible, estimated range of change, lower bound	$ 10,600,000		$ 10,600,000

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

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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 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 changes in the income tax rates.

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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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