Accounts Receivable

6 Months Ended

Jun. 30, 2020

Receivables [Abstract]

Accounts Receivable

3.     Accounts Receivable

(table only in thousands)	June 30, 2020			December 31, 2019
Contract receivables	$	54,614		$	58,881
Trade receivables		9,203			12,135
Allowance for doubtful accounts		(3,003	)		(2,582	)
Total accounts receivable	$	60,814		$	68,434

Balances billed but not paid by customers under retainage provisions in contracts within the Condensed Consolidated Balance Sheets amounted to approximately $1.3 million and $0.9 million at June 30, 2020 and December 31, 2019, respectively. Retainage receivables on contracts in progress are generally collected within a year after contract completion.

Bad debt expense was approximately $0.4 million and $0.3 million for the three-month periods ended June 30, 2020 and 2019, respectively, and $0.5 million and $0.4 million for the six-month periods ended June 30, 2020 and 2019, respectively.