8.	Receivables

The following table presents the components of receivables appearing in the accompanying Consolidated Balance Sheets at December 29, 2017 and September 29, 2017, as well as certain other related information (in thousands):

	December 29, 2017		September 29, 2017
Components of receivables:
Amounts billed, net	$	1,691,229	$	949,060
Unbilled receivables and other		1,577,005		1,118,144
Retentions receivable		25,268		35,339
Total receivables, net	$	3,293,502	$	2,102,543
Other information about receivables:
Amounts due from the United States federal government, included above, net of advanced billings	$	314,543	$	226,236
Claims receivable	$	4,600	$	4,600

Amounts billed, net consist of amounts invoiced to clients in accordance with the terms of our client contracts and are shown net of an allowance for doubtful accounts. We anticipate that substantially all of such billed amounts will be collected over the next twelve months.

Unbilled receivables and other and Retentions receivable represent reimbursable costs and amounts earned and reimbursable under contracts in progress as of the respective balance sheet dates. Such amounts become billable according to the contract terms, which usually provide that such amounts become billable upon the passage of time, achievement of certain milestones, or completion of the project. We anticipate that substantially all of such unbilled amounts will be billed and collected over the next twelve months.

Claims receivable are included in receivables in the accompanying Consolidated Balance Sheets and represent certain costs incurred on contracts to the extent it is probable that such claims will result in additional contract revenue and the amount of such additional revenue can be reliably estimated.