Disaggregation of Revenues

The following table disaggregates revenue by source:

Contract Balances

Depending on the timing of when a customer takes possession of product and when a customer makes payments for such product, the Company recognizes a customer trade receivable (asset) or a customer deposit (liability). The difference between the opening and closing balances of the Company's customer trade receivables and the customer deposit liability results from timing differences between the Company's performance and the customer's payment and due to the acquisitions for the years ended December 31, 2020 and 2019.

The opening and closing balances of the Company's customer trade receivables and customer deposit liability are as follows:

The Company also has customer trade receivables under longer term financing arrangements at interest rates ranging from 9% to 12% with repayment terms ranging for 12 to 18 months. Long term trade receivables at December 31, 2020 and 2019 are as follows:

The following table summarizes changes in notes receivable balances that have been deemed impaired.