Schedule of Segment Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended												12 Months Ended
	Dec. 31, 2013		Sep. 29, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012		Sep. 30, 2012	Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Segment Reporting Information [Line Items]
Net revenue	$ 285,301	[1],[2]	$ 433,376	$ 428,889	$ 280,367	$ 248,404	[3],[4]	$ 463,394	$ 548,284	[5]	$ 396,668	[6]	$ 1,427,933	[7]	$ 1,656,750	[7]	$ 1,429,061	[7]
Income (loss) from continuing operations before taxes	35,439	[1],[2]	87,552	80,357	(1,426)	(30,285)	[3],[4]	103,025	151,992	[5]	41,244	[6]	201,922	[8],[9]	265,976	[8],[9]	214,421	[8],[9]
Total assets	2,629,824	[10]				2,429,345	[10]						2,629,824	[10]	2,429,345	[10]	2,188,639	[10]
Property additions													106,731		119,080		86,097
Depreciation and amortization expense													150,687		145,514		106,681
Semiconductor Test
Segment Reporting Information [Line Items]
Net revenue													1,023,041		1,127,726		1,106,191
Income (loss) from continuing operations before taxes													153,797	[8],[9]	185,985	[8],[9]	219,651	[8],[9]
Total assets	632,840	[10]				604,127	[10]						632,840	[10]	604,127	[10]	581,026	[10]
Property additions													94,303		105,074		80,606
Depreciation and amortization expense													72,472		73,537		74,278
Wireless Test
Segment Reporting Information [Line Items]
Net revenue													251,871		286,355		28,390
Income (loss) from continuing operations before taxes													23,153	[8],[9]	83,077	[8],[9]	(20,579)	[8],[9]
Total assets	645,001	[10]				672,048	[10]						645,001	[10]	672,048	[10]	725,940	[10]
Property additions													5,358		7,608		794
Depreciation and amortization expense													51,675		50,362		13,057
System Test
Segment Reporting Information [Line Items]
Net revenue													153,021		242,669		294,480
Income (loss) from continuing operations before taxes													3,115	[8],[9]	34,164	[8],[9]	53,298	[8],[9]
Total assets	79,983	[10]				71,116	[10]						79,983	[10]	71,116	[10]	77,277	[10]
Property additions													7,070		6,398		4,697
Depreciation and amortization expense													5,180		4,549		4,192
Corporate And Eliminations
Segment Reporting Information [Line Items]
Income (loss) from continuing operations before taxes													21,857	[8],[9]	(37,250)	[8],[9]	(37,949)	[8],[9]
Total assets	1,272,000	[10]				1,082,054	[10]						1,272,000	[10]	1,082,054	[10]	804,396	[10]
Depreciation and amortization expense													$ 21,360		$ 17,066		$ 15,154

[1] Interest expense and other includes a $34.2 million gain from the sale of an equity investment.

[2] In the fourth quarter ended December 31, 2013, pension and post retirement net actuarial gains increased gross profit and net income by $2.7 million and $9.1 million, respectively. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[3] In the fourth quarter ended December 31, 2012, we corrected prior period income tax provision (benefit) errors that resulted in a $0.2 million income tax provision. These errors were not individually or in aggregate material to the fourth quarter of 2012 or any prior period.

[4] In the fourth quarter ended December 31, 2012, pension and postretirement actuarial losses decreased gross profit and net income by $8.1 million and $18.3 million, respectively. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[5] Restructuring and other includes $0.3 million of severance charges related to headcount reductions of 10 people in Semiconductor Test and ($6.5) million fair value adjustment to decrease the LitePoint acquisition contingent consideration.

[6] Restructuring and other includes a ($1.8) million fair value adjustment to decrease the LitePoint acquisition contingent consideration.

[7] Revenues attributable to a country are based on location of customer site.

[8] Interest income, interest expense and other, and pension and postretirement plans actuarial gains and losses are included in Corporate and Eliminations.

[9] Included in income (loss) from continuing operations before taxes are charges and credits related to restructuring and other and inventory charges.

[10] Total business assets are directly attributable to each business. Corporate assets consist of cash and cash equivalents, marketable securities and certain other assets.