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Note 1 - Description of Business and Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018
Advertising Expense | $ 1 | $ 2 | $ 1
Period for Creating Allowance for Doubtful Accounts (Day) | 120 days |  |
Accounts Receivable, Credit Loss Expense (Reversal) | $ 2 | 11 | $ 2
Asset Retirement Obligation, Ending Balance | $ 2 | $ 2 |
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Automotive [Member] |  |  |
Concentration Risk, Percentage | 21.00% | 25.00% | 25.00%

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- Definition Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 720 -SubTopic 35 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848 + Details
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