4. RECEIVABLES

Receivables include current notes, amounts billed to customers, claims, other receivables, and unbilled revenue on long-term contracts, which consists of amounts recognized as sales but not billed. Substantially all amounts of unbilled receivables are expected to be billed and collected in the subsequent year. An immaterial amount of unbilled receivables are subject to retainage provisions. The amount of claims and unapproved change orders within our receivables balances are immaterial.

Credit risk is diversified due to the large number of entities comprising the Corporation’s customer base and their geographic dispersion. The Corporation is either a prime contractor or subcontractor to various agencies of the U.S. Government. Revenues derived directly and indirectly from government sources (primarily the U.S. Government) were 36% and 34% of consolidated revenues in 2015 and 2014, respectively. Total receivables due primarily from the U.S Government were $165.6 million and $157.9 million at December 31, 2015 and 2014, respectively. Government (primarily the U.S. Government) unbilled receivables, net of progress payments, were $70.6 million and $72.9 million at December 31, 2015 and 2014, respectively.

The composition of receivables is as follows as of December 31:



(In thousands)	2015			2014
Billed receivables:
Trade and other receivables	$	435,172		$	363,241
Less: Allowance for doubtful accounts	(5,664		)	(5,619		)
Net billed receivables	429,508			357,622
Unbilled receivables:
Recoverable costs and estimated earnings not billed	153,045			150,526
Less: Progress payments applied	(16,264		)	(12,668		)
Net unbilled receivables	136,781			137,858
Receivables, net	$	566,289		$	495,480