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Schedule II (Details) - USD ($) | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
SEC Schedule, 12-09, Allowance, Credit Loss [Member] |  |  |  |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |
Balance at Beginning of Year |  | $ 25,000 | $ 0 | $ 0
(Recovered)/Charged to Costs and Expenses |  | 4,000 | 25,000 | 0
Charged to Other Accounts |  | 36,000 | 0 | 0
Deductions | [1] | 15,000 | 0 | 0
Balance at End of Year |  | 50,000 | 25,000 | 0
Allowance for Chargebacks [Member] |  |  |  |
SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |  |
Balance at Beginning of Year |  | 2,344,000 | 857,000 | 309,000
(Recovered)/Charged to Costs and Expenses |  | 1,316,000 | 2,639,000 | 981,000
Charged to Other Accounts |  | 0 | 0 | 0
Deductions | [1] | 3,184,000 | 1,152,000 | 433,000
Balance at End of Year |  | $ 476,000 | $ 2,344,000 | $ 857,000
[1] | (A) Amount represents uncollectible accounts written off.

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