Supplementary Balance Sheet Detail

The following tables present supplementary balance sheet details:



	At December 31,
	2013		2014
	(Dollars in thousands)

Inventories:
Raw materials and supplies	$	175,192	$	122,218
Work in process	239,114		176,141
Finished goods	76,108		84,544
	490,414		382,903
Prepaid expenses and other current assets:
Prepaid expenses	$	9,554	$	9,923
Current portion of deferred taxes	37,058		28,426
Value added tax and other indirect taxes receivable	25,061		39,837
Other current assets	2,117		3,437
	$	73,790	$	81,623
Property, plant and equipment:
Land and improvements	$	37,416	$	36,375
Buildings	196,802		193,427
Machinery and equipment and other	1,278,655		1,212,120
Construction in progress	76,007		58,899
	$	1,588,880	$	1,500,821
Other accrued liabilities:
Payrolls (including incentive programs)	$	9,330	$	6,151
Customer prepayments	9,599		5,534
Employee compensation and benefits	10,136		8,932
Other	11,874		22,702
	$	40,939	$	43,319
Other long term obligations:
Postretirement benefits	$	24,852	$	24,833
Pension and related benefits	54,173		65,882
Other	18,922		16,851
	$	97,947	$	107,566

The following table presents an analysis of the allowance for doubtful accounts:



	At December 31,
	2012			2013			2014
	(Dollars in thousands)
Balance at beginning of year	$	4,153		$	7,573		$	6,718
Additions	5,161			2,914			8,675
Deductions	(1,741		)	(3,769		)	(7,922		)
Balance at end of year	$	7,573		$	6,718		$	7,471

Inventories

We allocate fixed production overheads to the costs of conversion based on normal capacity of the production facilities. We recognize abnormal amounts of idle facility expense, freight, handling costs, and wasted materials (spoilage) as current period charges. During 2012, costs in excess of normal absorption were $3.5 million. During 2013 and 2014, there were no costs in excess of normal absorption.