4.Concentration of Risk and Enterprise Wide Disclosures

Accounts receivable in both reportable segments include amounts billed to governmental agencies and private customers and do not bear interest. Balances billed to customers but not paid pursuant to retainage provisions generally become payable upon contract completion and acceptance by the owner.

The table below presents the concentrations of current receivables (trade and retainage) at March 31, 2020 and December 31, 2019, respectively:


	March 31, 2020				December 31, 2019
Federal Government	$	1,340	1	%	$	4,765	3	%
State Governments		3,703	2	%		5,864	4	%
Local Governments		31,094	21	%		41,944	26	%
Private Companies		111,624	76	%		109,114	67	%
Gross receivables		147,761	100	%		161,687	100	%
Allowance for credit losses		(3,011)				(2,600)
Net receivables	$	144,750			$	159,087

At March 31, 2020 two customers in the Private Companies category accounted for 22.3% of total current receivables. At December 31, 2019, no single customer accounted for more than 10.0% of total current receivables.

Additionally, the table below represents concentrations of contract revenue by type of customer for the three months ended March 31, 2020 and 2019, respectively:


	Three months ended March 31,
	2020		%		2019		%
Federal Government	$	5,319	3	%	$	10,277	7	%
State Governments		12,232	7	%		4,055	3	%
Local Government		52,012	31	%		44,430	31	%
Private Companies		97,057	58	%		84,343	59	%
Total contract revenues	$	166,620	100	%	$	143,105	100	%

In the three months ended March 31, 2020 and 2019, no single customer exceeded 10.0% of total contract revenues.

The Company does not believe that the loss of any one of its customers would have a material adverse effect on the Company or its subsidiaries and affiliates since no single specific customer sustains such a large portion of receivables or contract revenue over time.

The concrete segment primarily purchases concrete from select suppliers. The loss of any one of these suppliers could adversely impact short-term operations.

Contract revenues generated outside the United States totaled 2.4% and 0.4% of total revenues for the three months ended March 31, 2020 and 2019, respectively, and were primarily located in the Caribbean Basin and Mexico.