Accounts Receivable and Inventories

Accounts receivable consist of the following:



(In thousands)	June 30 2018			December 31 2017
Trade accounts receivable	$	299,723		$	292,765
Less: Allowance for doubtful accounts	(4,333		)	(4,731		)
Trade accounts receivable, net	$	295,390		$	288,034

Other receivables (a)	$	27,349		$	20,224

(a) Other receivables include insurance claim receivables, employee receivables, tax claim receivables and other miscellaneous receivables not included in Trade accounts receivable, net.

The provision (benefit) for doubtful accounts related to trade accounts receivable was as follows:



	Three Months Ended					Six Months Ended
	June 30					June 30
(In thousands)	2018			2017		2018			2017
Provision (benefit) for doubtful accounts related to trade accounts receivable	$	(110	)	$	1,197	$	(156	)	$	1,175

Inventories consist of the following:



(In thousands)	June 30 2018		December 31 2017
Finished goods	$	21,463	$	26,415
Work-in-process	18,777		24,367
Contracts-in-process (b)	—		45,599
Raw materials and purchased parts	67,389		58,943
Stores and supplies	23,242		22,969
Total inventories	$	130,871	$	178,293

Contracts-in-process consist of the following:



(In thousands)	December 31 2017
Contract costs accumulated to date	$	73,740
Estimated forward loss provisions for contracts-in-process (c)	(28,141		)
Contracts-in-process (b) (d)	$	45,599


(b)	The Company has adopted the new revenue recognition standard utilizing the modified retrospective transition method, including use of practical expedients. Amounts previously reported as Contracts-in-progress have been recognized through the related cumulative catch-up adjustment. See Note 2, Recently Adopted and Recently Issued Accounting Standards for additional information.

(c) For periods prior to January 1, 2018, to the extent that the estimated forward loss provision exceeds accumulated contract costs it is included in the caption Other current liabilities on the Condensed Consolidated Balance Sheets and amounted to $3.0 million at December 31, 2017.

(d) At June 30, 2018 and December 31, 2017, the Company has $39.9 million and $97.9 million, respectively, of net customer advances related to SBB contracts. These amounts are included in the caption Current portion of advances on contracts and Advances on contracts, representing the non-current portion, on the Condensed Consolidated Balance Sheets.

The Company recognized an initial estimated forward loss provision related to the contracts with the federal railway system of Switzerland ("SBB") of $45.1 million for the year ended December 31, 2016. The Company recorded an additional forward loss provision of $1.8 million for the six months ended June 30, 2018. At June 30, 2018, the entire remaining estimated forward loss provision of $10.2 million is included in the caption Other current liabilities on the Condensed Consolidated Balance Sheets. The estimated forward loss provision represents the Company's best estimate based on currently available information. It is possible that the Company's overall estimate of costs to complete these contracts may increase, which would result in an additional estimated forward loss provision at such time, but the Company is unable to estimate any further possible loss or range of loss at this time.

The Company recognized $7.5 million and $15.5 million of revenues for the contracts with SBB, on an over time basis, utilizing an input method based on costs incurred for the three and six months ended June 30, 2018, respectively. The Company did not recognize any revenue for the contracts with SBB for the three and six months ended June 30, 2017. For three and six months ended June 30, 2018, consolidated product revenue gross margins were not significantly impacted by the revenue recognized under the SBB contracts. The Company is approximately 98% complete on the first contract and 21% complete on the second contract with SBB as of June 30, 2018.