Accounts Receivable

6 Months Ended

Jun. 30, 2019

Receivables [Abstract]

Accounts Receivable

3. Accounts Receivable

(table only in thousands)	June 30, 2019			December 31, 2018
Contract receivables	$	50,458		$	48,826
Trade receivables		12,375			7,296
Allowance for doubtful accounts		(2,796	)		(2,897	)
Total accounts receivable	$	60,037		$	53,225

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, 2019 and December 31, 2018, respectively. Retainage receivables on contracts in progress are generally collected within a year after contract completion.

Bad debt expense was $0.3 million and $0.5 million for the three-month periods ended June 30, 2019 and 2018, respectively, and $0.4 million and $0.6 for the six-month periods ended June 30, 2019 and 2018, respectively.