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Summary of Significant Accounting Policies - Contract Balances (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Accounts Receivable |  |
Accounts receivable - contracts with customers | $ 3,243 | $ 3,061
Accounts receivable - ASC 842 | 9,802 | 6,963
Total Accounts Receivable | 13,045 | 10,024
Less: Allowance for doubtful accounts | (1,161) | (918)
Total Accounts Receivable, net | 11,884 | 9,106
Deferred income | $ 1,103 | $ 640

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