Summary of Significant Accounting Policies, Product Warranty and Overstock Returns and Accounting for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Product Warranty and Overstock Returns [Abstract]
Product warranty period	90 days
Accounting for Income Taxes [Abstract]
Valuation allowance	$ 399	$ 377
Net deferred tax asset	$ 42,334	$ 32,420
U.S. Federal income tax rate	21.00%	35.00%	35.00%

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Refers to the product warranty period in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount, after allocation of valuation allowances and deferred tax liability, of deferred tax asset attributable to deductible differences and carryforwards, without jurisdictional netting.

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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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