Accounts Receivable

12 Months Ended

Dec. 31, 2016

Receivables [Abstract]

Loans, Notes, Trade and Other Receivables Disclosure [Text Block]

4. Accounts Receivable

Accounts receivable consisted of the following at December 31:

(in thousands)	2016			2015
Contract receivables	$	200,732		$	159,794
Contract retainages		32,486			27,474
Other		1,856			343
		235,074			187,611
Less: Allowance for doubtful accounts		(432	)		(376	)
	$	234,642		$	187,235

The roll-forward of activity in the allowance for doubtful accounts was as follows for the years ended December 31:

(in thousands)	2016			2015		2014
Balance at beginning of period	$	376		$	1,179	$	1,132
Less: Reduction in (provision for) allowances		(146	)		528		(96	)
Less: Write offs, net of recoveries		90			275		49
Balance at end of period	$	432		$	376	$	1,179