Accounts Receivable, Net

12 Months Ended

Dec. 31, 2017

Receivables [Abstract]

Accounts Receivable, Net

5. ACCOUNTS RECEIVABLE, NET

Unbilled amounts represent sales for which billings have not been presented to customers by period-end. These amounts are generally billed and collected within one year. Substantially all accounts receivable at December 31, 2017 are expected to be collected in 2018. The company does not believe it has significant exposure to credit risk, as accounts receivable and the related unbilled amounts are primarily due from the U.S. Government either as the ultimate customer or in connection with foreign military sales. Progress and performance-based payments are reflected as an offset to the related unbilled accounts receivable balance for contracts accounted for under the cost-to-cost method of percentage-of-completion accounting.

Accounts receivable consisted of the following:

	December 31
$ in millions	2017			2016
Due from U.S. Government (1)
Billed	$	656		$	482
Unbilled	10,818			9,730
Progress and performance-based payments received	(8,068		)	(7,484		)
Total due from U.S. Government	3,406			2,728
Due from International and Other Customers
Billed	218			200
Unbilled	3,397			3,895
Progress and performance-based payments received	(2,966		)	(3,461		)
Total due from International and Other Customers	649			634
Total accounts receivable	4,055			3,362
Allowance for doubtful accounts	(79		)	(63		)
Total accounts receivable, net	$	3,976		$	3,299

⁽¹⁾  Includes receivables due from the U.S. Government associated with foreign military sales (FMS). For FMS, we contract with and are paid by the U.S. Government.