Inventories (Tables)

12 Months Ended

Dec. 31, 2017

Inventories consisted of the following (in thousands):



	December 31, 2017			December 31, 2016
Raw materials	$	23,269		$	24,805
Work-in-process	—			12
Finished goods	4,012			5,005
	27,281			29,822
Less: inventory valuation allowance	(23,016		)	(9,801		)
Inventories, net	$	4,265		$	20,021

Charges Associated with Inventory

The Company recorded the following charges associated with the valuation of inventory, inventory deposit and the adverse purchase commitment liability for the years ended December 31 (in thousands):



	2017		2016			2015
Inventory, net	$	15,050	$	6,120		$	1,447
Adverse purchase commitments^(A)	2,913		(1,908		)	1,831
Net charges^(B)	$	17,963	$	4,212		$	3,278

Change in Inventory Valuation Allowance

The following is a summary of the change in the Company’s inventory valuation allowance for the years ended December 31 (in thousands):



	2017			2016
Inventory valuation allowance, beginning of the year	$	9,801		$	5,317
Usage:
Inventory scrapped	(870		)	(1,636		)
Inventory utilized	(882		)	(954		)
Subtotal—usage	(1,752		)	(2,590		)
Write-downs of inventory valuation and transfers to/from other liabilities ^(A)	14,967			7,074
Inventory valuation allowance, end of the year	$	23,016		$	9,801


(A)	Transfer to/from other liabilities is related to obsolete inventory purchased from contract manufacturers during the year which was previously reserved for as an adverse purchase commitment. (Note 9—Other Accrued and Other Long-Term Liabilities and Note 13—Commitments and Contingencies.)