Contingency (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018	Mar. 28, 2018
Commitments and Contingencies Disclosure [Abstract]
Sales tax examination excluding penalties and interest accrued			$ 824
Sales tax examination penalties and interest accrued			339
Sales tax examination liability refund adjustment from settlement with tax authority			$ 1,163
Sales tax contingent liabilities	$ 246	$ 96