Net Receivables

Net receivables, including amounts due under long-term contracts consisted of the following:



	December 31, 2015			March 31, 2015
	As Restated			As Restated
Billed receivables
U.S. Government contracts	$	121,756		$	186,430
Commercial and other	95,766			88,601
Unbilled receivables
U.S. Government contracts	807,778			866,709
Commercial and other	646,549			559,481
Less allowance for doubtful accounts	(1,028		)	(4,692		)
Net receivables	$	1,670,821		$	1,696,529

Receivable balances are shown net of customer progress payments received of $584,325 at December 31, 2015 and $585,932 at March 31, 2015.

Unbilled receivables represent the balance of recoverable costs and accrued profit, comprised 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 at the balance sheet date. These amounts include expected additional billable general overhead costs and fees on flexibly priced contracts awaiting final rate negotiations.

At December 31, 2015 and March 31, 2015, the aggregate amount of contract-related unbilled receivables the Company does not expect to collect within the next 12 months was $311,600 and $298,900, respectively.

The Company records an allowance for doubtful accounts, reducing the receivables balance to an amount the Company estimates is collectible from customers. Estimates used in determining the allowance for doubtful accounts are based on current trends, aging of accounts receivable, periodic credit evaluations of customers’ financial condition and historical collection experience.

Changes in the allowance for doubtful accounts were as follows:



Balance, March 31, 2013	$	4,801
Expense	609
Write-offs	(626		)
Other adjustments	107
Balance, March 31, 2014	4,891
Expense	599
Write-offs	(17		)
Other adjustments	(781		)
Balance, March 31, 2015	4,692
Expense	12
Write-offs	(3,737		)
Other adjustments	61
Balance, December 31, 2015	$	1,028