Receivables, net

12 Months Ended

Dec. 31, 2017

Receivables [Abstract]

Receivables, Net

Receivables, net (in thousands)

December 31,	2017		2016
Construction contracts completed and in progress:
Billed	$	252,467	$	206,570
Unbilled	77,135		81,590
Retentions	91,135		84,878
Total construction contracts completed and in progress	420,737		373,038
Construction material sales	42,192		29,357
Other	17,014		17,523
Total gross receivables	479,943		419,918
Less: allowance for doubtful accounts	152		573
Total net receivables	$	479,791	$	419,345

Receivables include amounts billed and billable to clients for services provided as of the end of the applicable period and do not bear interest. To the extent costs are not contractually billable or have not been earned, including 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 in the consolidated balance sheets. As of December 31, 2017 and 2016, the aggregate claim recovery estimates included in these balances were approximately $26.7 million and $12.3 million, respectively. Included in other receivables at December 31, 2017 and 2016 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 December 31, 2017 and 2016, the estimated recovery from back charge claims included in Other receivables was $1.1 million and $0.3 million, respectively.

During the year ended December 31, 2017, our largest volume customer, including both prime and subcontractor arrangements, was the California Department of Transportation (“Caltrans”). Revenue recognized from contracts with Caltrans during 2017 represented $281.7 million (9.4% of our total revenue) of which $219.9 million (13.2% of segment revenue) was in the Construction segment, $57.2 million (5.5% of segment revenue) in the Large Project Construction segment and $4.6 million (1.6% of segment revenue) was in the Construction Materials segment. During the year ended December 31, 2016, our largest volume customer, including both prime and subcontractor arrangements, was Caltrans. Revenue recognized from contracts with Caltrans during 2016 represented $222.4 million (8.8% of total revenue), of which $173.4 million (12.7% of segment revenue) was in the Construction segment and $48.7 million (5.5% of segment revenue) was in the Large Project Construction segment. During the year ended December 31, 2015, our largest volume customer, including both prime and subcontractor arrangements, was the New York State Department of Transportation (“NYSDOT”). Revenue recognized from contracts with NYSDOT during 2015 represented $199.0 million (8.4% of total revenue), all of which was in the Large Project Construction segment (24.5% of segment revenue).

We regularly review our accounts receivable, including past due amounts, to determine their probability of collection. If it is probable that an amount is uncollectible, it is charged to bad debt expense and a corresponding reserve is established in allowance for doubtful accounts. If it is deemed certain that an amount is uncollectible, the amount is written off.

Certain construction contracts include retainage provisions. 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 December 31, 2017, the majority of the retentions receivable are expected to be collected within one year. As of December 31, 2017 and 2016, there were no retentions receivables determined to be uncollectible.