4. Accounts Receivable

Accounts receivable consisted of the following at December 31:


(in thousands)	2015			2014
Contract receivables	$	159,794		$	120,295
Contract retainages		27,474			38,379
Other		343			606
		187,611			159,280
Less: Allowance for doubtful accounts		(376	)		(1,179	)
	$	187,235		$	158,101

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


(in thousands)	2015		2014			2013
Balance at beginning of period	$	1,179	$	1,132		$	1,305
Less: Reduction in (provision for) allowances		528		(96	)		159
Less: Write offs, net of recoveries		275		49			14
Balance at end of period	$	376	$	1,179		$	1,132