Expected Credit Losses - Type Of Customer Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Expected Credit Losses
Accounts receivable and notes receivable, current	$ 2,105	$ 1,567
Contract assets, net	794
Long-term notes receivable, net of current portion	477
Total allowance for expected credit losses on customer receivables	$ 3,376