RECEIVABLES, CONTRACT ASSETS, AND DEFERRED REVENUE

Receivables



(in thousands)	March 31, 2019		December 31, 2018
Accounts receivable	$	135,352	$	180,872
Unbilled receivables	161,480		172,656
Long-term unbilled receivables	130,494		151,237
	$	427,326	$	504,765

Unbilled receivables are client committed amounts for which revenue recognition precedes billing, and billing is solely subject to the passage of time.

As of March 31, 2019 and December 31, 2018, the allowance for doubtful accounts was not material.

Unbilled receivables are expected to be billed in the future as follows:



(Dollars in thousands)	March 31, 2019
1 year or less	$	161,480	55	%
1-2 years	86,496		30	%
2-5 years	43,998		15	%
	$	291,974	100	%

Contract assets and deferred revenue



(in thousands)	March 31, 2019		December 31, 2018
Contract assets ⁽¹⁾	$	3,380	$	3,711
Long-term contract assets ⁽²⁾	1,818		2,543
	$	5,198	$	6,254
Deferred revenue	$	180,845	$	185,145
Long-term deferred revenue ⁽³⁾	5,866		5,344
	$	186,711	$	190,489

⁽¹⁾Included in other current assets.⁽²⁾ Included in other long-term assets.⁽³⁾Included in other long-term liabilities.

Contract assets are amounts under client contracts where revenue recognized exceeds the amount billed to the client and the right to payment is subject to conditions other than the passage of time, such as the completion of a related performance obligation. Deferred revenue consists of billings and payments received in advance of revenue recognition. Contract assets and deferred revenue are netted at the contract level for each reporting period.

The change in deferred revenue in the three months ended March 31, 2019 was primarily due to $89.4 million of revenue recognized, excluding the impact of netting contract assets and deferred revenue at the contract level, during the period that was included in deferred revenue at December 31, 2018, partially offset by new billings in advance of revenue recognition.