Accounts Receivable

12 Months Ended

Dec. 31, 2019

NOTE F—ACCOUNTS RECEIVABLE

At December 31, 2019 and December 31, 2018, accounts receivable (in thousands) consisted of the following:



	December 31, 2019			December 31, 2018
Trade receivables	$	178,182		$	198,435
Less: Allowance for doubtful accounts	(8,984		)	(6,751		)
Net trade receivables	169,198			191,684
Other receivables⁽¹⁾	13,040			23,802
Total accounts receivable	$	182,238		$	215,486



(1	)	At December 31, 2019, other receivables include $8.1 million of refundable alternative minimum tax credits. At December 31, 2018, other receivables included $16.0 million of refundable alternative minimum tax credits that were refunded during the third quarter of 2019.

Changes in our allowance for doubtful accounts (in thousands) during the years ended December 31, 2019 and 2018 were as follows:



	December 31, 2019			December 31, 2018
Beginning balance	$	6,751		$	7,100
Bad debt provision	3,466			315
Write-offs	(1,233		)	(664		)
Ending balance	$	8,984		$	6,751

Our ten largest customers accounted for approximately 43%, 48% and 58% of total sales during the year ended December 31, 2019, 2018 and 2017, respectively. Sales to one of our customers accounted for 11% of our total sales during the year ended December 31, 2019. Sales to one of our customers accounted for 15% of our total sales during the year ended December 31, 2018. Sales to two of our customers accounted for 15% and 12% of our total sales during the year ended December 31, 2017. No other customers accounted for 10% or more of our total sales. At December 31, 2019, one of our customers' accounts receivable represented 12% of our total trade accounts receivable, net of allowance. At December 31, 2018, the same customer's accounts receivable represented 18% of our total trade accounts receivable, net of allowance. No other customers accounted for 10% or more of our total trade accounts receivable.