Accounts Receivable

12 Months Ended

Dec. 31, 2017

Receivables [Abstract]

Accounts Receivable

3. Accounts Receivable

(Table only in thousands)	2017			2016
Trade receivables	$	11,603		$	11,976
Contract receivables		60,543			72,835
Allowance for doubtful accounts		(4,156	)		(1,749	)
Total accounts receivable	$	67,990		$	83,062

Balances billed, but not paid by customers under retainage provisions in contracts that are recorded in deferred charges and other assets within the Consolidated Balance Sheets, amounted to approximately $2.5 million and $3.2 million at December 31, 2017 and 2016, respectively. Retainage receivables on contracts in progress are generally collected within a year or two subsequent to contract completion.

Provision for doubtful accounts was approximately $3.9 million, $0.8 million and $0.7 million during 2017, 2016 and 2015, respectively, while accounts charged to the allowance were $1.5 million, $0.3 million and $0.2 million during 2017, 2016 and 2015, respectively.