Percentage of change in the effective tax rate due to excess tax benefits recognized from share-based compensation.

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Amount of deferred tax assets for which it is more likely than not that a tax benefit will not be realized.

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

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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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The increase (decrease) during the reporting period in the amounts payable to taxing authorities for taxes that are based on the reporting entity's earnings, net of amounts receivable from taxing authorities for refunds of overpayments or recoveries of income taxes, and in deferred and other tax liabilities and assets.

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- Definition

Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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The amount of the tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws.

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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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Amount of statutory penalties accrued for a tax position claimed or expected to be claimed by the entity, in its tax return.

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Amount of expense for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return.

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Amount of interest expense accrued for an underpayment of income taxes.

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The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate.

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Amount of increase (decrease) in the valuation allowance for a specified deferred tax asset.

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Income Taxes - Narrative (Details) - USD ($) $ in Thousands	6 Months Ended		12 Months Ended
Income Taxes - Narrative (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018
Tax Credit Carryforward
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%	35.00%
Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent			6.70%
Deferred tax asset valuation allowance
Deferred tax asset valuation allowance	$ (10,400)		$ (4,866)	$ (10,400)
Unrecognized tax benefits that if recognized would reduce the effective tax rate			5,400
Accrued interest			500
Accrued penalties related to uncertain tax positions			100
Benefit for interest and penalties			100
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount			4,800
Foreign
Tax Credit Carryforward
Net operating loss carryforwards			900
Research and development tax credit carryforward \| State and Local Jurisdiction [Member]
Tax Credit Carryforward
Tax credit carryforward			3,900
Research and development tax credit carryforward \| State and Local Jurisdiction [Member]
Tax Credit Carryforward
Tax credit carryforward			4,000
Accounting Standards Update 2016-09 [Member]
Tax Credit Carryforward
Increase (Decrease) in Income Taxes			$ 3,800	$ 3,000
EffectiveIncomeTaxRateReconciliationChangeInTaxRateDueToExcessTaxBenefitsRecognizedFromShareBasedCompensation			(1.00%)	1.00%