Certain Balance Sheet Components (Tables)

9 Months Ended

Sep. 30, 2017

Balance Sheet Related Disclosures [Abstract]

Accounts Receivable, Net [Table Text Block]

Accounts receivable, net	September 30, 2017		December 31, 2016
	(in thousands)
Trade receivables (net of allowance of $3,991 and $3,320)	$	351,255	$	299,870
Unbilled receivables	24,894		51,636
Total accounts receivable, net	$	376,149	$	351,506

Allowance for Credit Losses on Financing Receivables [Table Text Block]

Allowance for doubtful accounts activity	Three Months Ended September 30,						Nine Months Ended September 30,
	2017			2016			2017			2016
	(in thousands)
Beginning balance	$	3,502		$	3,939		$	3,320		$	5,949
Provision for doubtful accounts, net	769			353			1,513			265
Accounts written-off	(310		)	(77		)	(1,115		)	(1,919		)
Effect of change in exchange rates	30			39			273			(41		)
Ending balance	$	3,991		$	4,254		$	3,991		$	4,254

Inventories [Table Text Block]

Inventories	September 30, 2017		December 31, 2016
	(in thousands)
Materials	$	131,616	$	103,274
Work in process	9,158		7,925
Finished goods	66,929		51,850
Total inventories	$	207,703	$	163,049

Property, Plant, and Equipment, Net [Table Text Block]

Property, plant, and equipment, net	September 30, 2017			December 31, 2016
	(in thousands)
Machinery and equipment	$	292,330		$	279,746
Computers and software	106,287			98,125
Buildings, furniture, and improvements	134,536			122,680
Land	18,596			17,179
Construction in progress, including purchased equipment	37,846			29,358
Total cost	589,595			547,088
Accumulated depreciation	(396,811		)	(370,630		)
Property, plant, and equipment, net	$	192,784		$	176,458

Depreciation Expense [Table Text Block]

Depreciation expense	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
	(in thousands)
Depreciation expense	$	10,907	$	11,086	$	30,856	$	32,561