Certain Balance Sheet Components



Accounts receivable, net	December 31, 2012		December 31, 2011
	(in thousands)
Trade receivables (net of allowance of $7,372 and $6,049)	$	329,352	$	328,845
Unbilled receivables	45,974		42,796
Total accounts receivable, net	$	375,326	$	371,641

At December 31, 2012 and 2011, $20.0 million and $2.5 million were recorded within trade receivables as billed but not yet paid by customers in accordance with contract retainage provisions. At December 31, 2012 and December 31, 2011, contract retainage amounts that were unbilled and classified as unbilled receivables were $11.1 million and $7.4 million. These contract retainage amounts within trade receivables and unbilled receivables are expected to be collected within the following 12 months.

We had no long-term unbilled receivables or long-term retainage contracts at December 31, 2012 as we expect to bill and collect all contract retainage receivables within the following 12 months. At December 31, 2011, long-term unbilled receivables and long-term retainage contract receivables totaled $31.5 million.



Allowance for doubtful account activity	Year Ended December 31,
	2012			2011
	(in thousands)
Beginning balance	$	6,049		$	9,045
Provision (release) of doubtful accounts, net	1,851			(71		)
Accounts written-off	(595		)	(2,599		)
Effects of change in exchange rates	67			(326		)
Ending balance	$	7,372		$	6,049



Inventories	December 31, 2012		December 31, 2011
	(in thousands)
Materials	$	92,038	$	112,470
Work in process	12,568		16,306
Finished goods	66,113		67,061
Total inventories	$	170,719	$	195,837

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 $5.0 million and $7.4 million at December 31, 2012 and December 31, 2011, respectively.



Property, plant, and equipment, net	December 31, 2012			December 31, 2011
	(in thousands)
Machinery and equipment	$	287,791		$	269,611
Computers and software	84,980			74,885
Buildings, furniture, and improvements	146,191			140,064
Land	25,318			26,126
Construction in progress, including purchased equipment	26,097			20,687
Total cost	570,377			531,373
Accumulated depreciation	(315,165		)	(268,703		)
Property, plant, and equipment, net	$	255,212		$	262,670



Depreciation expense	Year Ended December 31,
	2012		2011		2010
	(in thousands)
Depreciation expense	$	61,661	$	66,072	$	62,154