Income Taxes Income Tax (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Valuation Allowance [Line Items]
Provision for income taxes	$ 10,198	$ 12,346	$ 21,628	$ 29,994
Effective Income Tax Rate Reconciliation, Percent	25.80%	35.60%	22.30%	34.80%
Corporate Federal Tax Rate			21.00%	35.00%
Effective Income Tax Rate Reconciliation, Tax Credit, Amount			$ 3,000

Corporate Federal Tax Rate - as a result of the Tax Cuts and Jobs Act of 2017

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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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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 tax credits. Including, but not limited to, research credit, foreign tax credit, investment tax credit, and other tax credits.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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