Certain Balance Sheet Components



Accounts receivable, net	March 31, 2013		December 31, 2012
	(in thousands)
Trade receivables (net of allowance of $6,144 and $7,372)	$	318,223	$	329,352
Unbilled receivables	38,005		45,974
Total accounts receivable, net	$	356,228	$	375,326

At March 31, 2013 and December 31, 2012, $19.5 million and $20.0 million were recorded within trade receivables as billed but not yet paid by customers, in accordance with contract retainage provisions. At March 31, 2013 and December 31, 2012, contract retainage amounts that were unbilled and classified as unbilled receivables were $7.6 million and $11.1 million. These contract retainage amounts within trade receivables and unbilled receivables are expected to be collected within the following 12 months.

At March 31, 2013, long-term unbilled receivables totaled $2.5 million. These long-term unbilled receivables are classified within other long-term assets, as collection is not anticipated within the following 12 months but is expected during 2014. We had no billed long-term contract retainage receivables at March 31, 2013, as we expect to collect all contract retainage receivables within the following 12 months. We had no long-term unbilled receivables or long-term contract retainage receivables at December 31, 2012.



Allowance for doubtful account activity	Three Months Ended March 31,
	2013			2012
	(in thousands)
Beginning balance	$	7,372		$	6,049
Provision (release) of doubtful accounts, net	(904		)	(60		)
Accounts written-off	(105		)	(239		)
Effects of change in exchange rates	(219		)	233
Ending balance	$	6,144		$	5,983



Inventories	March 31, 2013		December 31, 2012
	(in thousands)
Materials	$	102,654	$	92,038
Work in process	11,846		12,568
Finished goods	67,954		66,113
Total inventories	$	182,454	$	170,719

Our inventory levels may vary period to period as a result of our factory scheduling and the timing of contract fulfillments, which may include the buildup of finished goods for shipment.

Consigned inventory is held at third-party locations; however, we retain title to the inventory until purchased by the third-party. Consigned inventory, consisting of raw materials and finished goods, was $4.7 million and $5.0 million at March 31, 2013 and December 31, 2012, respectively.



Property, plant, and equipment, net	March 31, 2013			December 31, 2012
	(in thousands)
Machinery and equipment	$	284,291		$	287,791
Computers and software	85,958			84,980
Buildings, furniture, and improvements	141,653			146,191
Land	24,518			25,318
Construction in progress, including purchased equipment	30,108			26,097
Total cost	566,528			570,377
Accumulated depreciation	(317,916		)	(315,165		)
Property, plant, and equipment, net	$	248,612		$	255,212



Depreciation expense and capitalized interest	Three Months Ended March 31,
	2013		2012
	(in thousands)
Depreciation expense	$	14,013	$	15,314
Capitalized interest	43		—

In conjunction with the upgrade of our global enterprise resource planning software systems, we have capitalized $12.3 million within construction in progress. Amounts capitalized include internal labor costs and related benefits, software, third-party consulting fees, and $43,000 of interest.