Receivables, net



(in thousands)	September 30, 2016		December 31, 2015		September 30, 2015
Construction contracts:
Completed and in progress	$	347,320	$	206,756	$	300,188
Retentions	97,385		91,670		82,344
Total construction contracts	444,705		298,426		382,532
Construction Material sales	50,768		28,727		68,449
Other	17,760		14,033		5,979
Total gross receivables	513,233		341,186		456,960
Less: allowance for doubtful accounts	481		364		272
Total net receivables	$	512,752	$	340,822	$	456,688

Receivables include amounts billed and billable to clients for services provided as of the end of the applicable period and, except for escrow receivables, do not bear interest. Included in Other receivables at September 30, 2016, December 31, 2015 and September 30, 2015 were items such as estimated recovery from back charge claims, notes receivable, fuel tax refunds, receivables from vendors and income tax refunds. No such receivables individually exceeded 10% of total net receivables at any of these dates. As of September 30, 2016 and December 31, 2015, the estimated recovery from back charge claims included in Other receivables was $9.3 million and $6.5 million, respectively, and there were no receivables related to back charges as of September 30, 2015.

To the extent costs are not contractually billable or have not been earned, such as claim recovery estimates, the associated revenue is included in costs and estimated earnings in excess of billings or billings in excess of costs and estimated earnings, respectively, on the condensed consolidated balance sheets. As of September 30, 2016, December 31, 2015 and September 30, 2015, the aggregate claim recovery estimates, included in these balances, were approximately $7.8 million, $8.8 million and $11.0 million, respectively. Ultimate settlement with the customer is dependent on the claims resolution process and could extend beyond one year or the project operating cycle.

Certain construction contracts include retainage provisions and the associated retention receivables are considered financing receivables. The balances billed but not paid by customers pursuant to these provisions generally become due upon completion and acceptance of the project work or products by the owners. No retention receivable individually exceeded 10% of total net receivables at any of the presented dates. As of September 30, 2016, the majority of the retentions receivable are expected to be collected within one year.

We segregate our retention receivables into two categories: escrow and non-escrow. The balances in each category were as follows:



(in thousands)	September 30, 2016		December 31, 2015		September 30, 2015
Escrow	$	18,797	$	21,958	$	21,590
Non-escrow	78,588		69,712		60,754
Total retention receivables	$	97,385	$	91,670	$	82,344

The escrow receivables include amounts due to Granite that have been deposited into an escrow account and bear interest. Typically, escrow retention receivables are held until work on a project is complete and has been accepted by the owner who then releases those funds, along with accrued interest, to us. There is minimal risk of not collecting on these amounts.

As of all periods presented, there were no significant collectability issues related to non-escrow retention receivables.