Balance Sheet Details

The detail of certain assets in the Consolidated Balance Sheets consists of the following (in millions).

Cash and cash equivalents

The Company’s cash equivalents consist of overnight cash sweep accounts that are invested on a daily basis. Cash and cash equivalents at December 28, 2014 and December 27, 2015 were $33.5 million and $28.5 million, respectively and approximated their fair value.

Accounts receivable, net (in millions)

Receivables including amounts due under long-term contracts are summarized as follows:



	December 28, 2014			December 27, 2015
Billed, current	$	119.0		$	96.6
Unbilled, current	100.4			112.0
Total current accounts receivable	219.4			208.6
Allowance for doubtful accounts	(1.9		)	(1.8		)
Total accounts receivable, net	$	217.5		$	206.8

Unbilled receivables represent the balance of recoverable costs and accrued profit, composed principally of revenue recognized on contracts for which billings have not been presented to the customer because the amounts were earned but not contractually billable as of the balance sheet date. Retainages receivable were $6.1 million as of December 28, 2014 and $6.4 million as of December 27, 2015 and are included in accounts receivable, net in the Consolidated Balance Sheets.

Substantially all accounts receivable at December 27, 2015, are expected to be collected in 2016. The Company does not believe it has significant exposure to credit risk, as accounts receivable and the related unbilled amounts are primarily from contracts where the end customer is the U.S. Government.

U.S. Government contract receivables where the Company is the prime contractor included in accounts receivable, net (in millions)



	December 28, 2014		December 27, 2015
Billed	$	19.1	$	13.5
Unbilled	21.2		31.0
Total U.S. Government contract receivables	$	40.3	$	44.5

Inventoried costs, net of progress payments (in millions)



	December 28, 2014			December 27, 2015
Raw materials	$	30.1		$	32.9
Work in process	13.3			19.2
Finished goods	2.8			2.6
Supplies and other	2.1			1.6
Subtotal inventoried costs	48.3			56.3
Less customer advances and progress payments	(0.9		)	(0.7		)
Total inventoried costs	$	47.4		$	55.6

Property and equipment, net (in millions)



	December 28, 2014			December 27, 2015
Land and buildings	$	12.8		$	13.3
Computer equipment and software	24.3			27.0
Machinery and equipment	41.0			47.4
Furniture and office equipment	10.0			5.8
Leasehold improvements	13.0			10.9
Construction in progress	8.0			5.7
Property and equipment	109.1			110.1
Accumulated depreciation and amortization	(47.5		)	(53.9		)
Total property and equipment, net	$	61.6		$	56.2

Depreciation expense was $13.6 million, $13.3 million and $12.5 million for the years ended December 29, 2013, December 28, 2014, and December 27, 2015, respectively.