Operating Segments and Related Information - Results of Discontinued Operations (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Segment Reporting [Abstract]
Revenue, net of refund liabilities	$ 0	$ 0	$ 157	$ 0
Cost of sales	319	337	831	1,013
Selling, general and administrative expense	6	5	9	10
Depreciation and amortization	0	2	1	6
Loss from discontinued operations before income taxes	(325)	(344)	(684)	(1,029)
Income tax expense	0	0	0	0
Net loss from discontinued operations	$ (325)	$ (344)	$ (684)	$ (1,029)

Amount before tax of income (loss) from a discontinued operation. Includes, but is not limited to, the income (loss) from operations during the phase-out period, gain (loss) on disposal, gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and adjustments to a prior period gain (loss) on disposal.

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Amount of tax expense (benefit) related to a discontinued operation. Includes, but is not limited to, tax expense (benefit) related to income (loss) from operations during the phase-out period, tax expense (benefit) related to gain (loss) on disposal, tax expense (benefit) related to gain (loss) for reversal of write-down (write-down) to fair value, less cost to sell, and tax expense (benefit) related to adjustments of a prior period gain (loss) on disposal.

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