CONTRACT ASSETS AND LIABILITIES

The components of contract assets and contract liabilities consisted of the following:



	Balance Sheet Classification	December 31, 2018		December 31, 2017
Assets:		(in thousands)
Contract assets	Unbilled receivables, net	$	59,357	$	37,785
Liabilities:
Contract liabilities	Deferred revenue	$	1,622	$	6,090

The timing of revenue recognition, billings, and cash collections result in billed accounts receivable, unbilled receivables, and customer advances and deposits. Contract assets (unbilled receivables) result from timing differences between revenue recognition and billing in accordance with agreed-upon contractual terms, which typically occurs subsequent to revenue being recognized. Contract liabilities (deferred revenue) consist of advance payments and billings in excess of revenue recognized. The contract assets and liabilities are reported in a net position on a contract by contract basis.

The increase in contract assets (unbilled receivables) during the year ended December 31, 2018, was primarily due to billable receivables now being classified as contract assets and to the timing of billings and revenue recognized on certain contracts. The decrease in contract liabilities (deferred revenue) during the year ended December 31, 2018, was primarily due to timing of cash collection and subsequent recognition of revenue on the related programs, respectively. The Company expects to bill its customers for a majority of the December 31, 2018 contract assets during 2019.

During the year ended December 31, 2018, the Company recognized revenue of $6.5 million related to contract liabilities which existed at January 1, 2018. There were no material impairment losses recognized on contract assets for the year ended December 31, 2018.