Schedule of Segment Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Net revenue	$ 248,404	[1],[2],[3]	$ 463,394	[4]	$ 548,284	[5]	$ 396,668	[6]	$ 296,992	[7],[8]	$ 344,389	[9]	$ 410,519	[10]	$ 377,161	[11]	$ 1,656,750		$ 1,429,061		$ 1,566,162
Income (loss) from continuing operations before taxes	(30,285)	[1],[2],[3]	103,025	[4]	151,992	[5]	41,244	[6]	(15,549)	[7],[8]	58,465	[9]	95,923	[10]	75,582	[11]	265,976	[12],[13]	214,421	[12],[13]	396,347	[12],[13]
Total assets from continuing operations	2,429,345	[14]							2,188,639	[14]							2,429,345	[14]	2,188,639	[14]	1,801,173	[14]
Property additions																	119,080	[15]	86,097	[15]	76,044	[15]
Depreciation and amortization expense																	142,799	[15]	104,378	[15]	93,516	[15]
Semiconductor Test
Segment Reporting Information [Line Items]
Net revenue																	1,127,726		1,106,191		1,413,295
Income (loss) from continuing operations before taxes																	185,985	[12],[13]	212,201	[12],[13]	414,994	[12],[13]
Total assets from continuing operations	604,127	[14]							581,026	[14]							604,127	[14]	581,026	[14]	611,694	[14]
Property additions																	96,590	[15]	76,164	[15]	69,935	[15]
Depreciation and amortization expense																	67,922	[15]	60,985	[15]	66,709	[15]
Wireless Test
Segment Reporting Information [Line Items]
Net revenue																	286,355		28,390
Income (loss) from continuing operations before taxes																	83,077	[12],[13]	(20,579)	[12],[13]
Total assets from continuing operations	672,048	[14]							725,940	[14]							672,048	[14]	725,940	[14]
Property additions																	7,608	[15]	794	[15]
Depreciation and amortization expense																	50,242	[15]	13,057	[15]
Systems Test Group
Segment Reporting Information [Line Items]
Net revenue																	242,669		294,480		152,867
Income (loss) from continuing operations before taxes																	34,164	[12],[13]	51,802	[12],[13]	(8,877)	[12],[13]
Total assets from continuing operations	71,116	[14]							77,277	[14]							71,116	[14]	77,277	[14]	95,402	[14]
Property additions																	5,146	[15]	4,043	[15]	3,142	[15]
Depreciation and amortization expense																	3,747	[15]	1,857	[15]	1,854	[15]
Corporate And Eliminations
Segment Reporting Information [Line Items]
Income (loss) from continuing operations before taxes																	(37,250)	[12],[13]	(29,003)	[12],[13]	(9,770)	[12],[13]
Total assets from continuing operations	1,082,054	[14]							804,396	[14]							1,082,054	[14]	804,396	[14]	1,094,077	[14]
Property additions																	9,736	[15]	5,096	[15]	2,967	[15]
Depreciation and amortization expense																	$ 20,888	[15]	$ 28,479	[15]	$ 24,953	[15]

[1] Restructuring and other, net includes a ($0.4) million fair value adjustment to decrease LitePoint acquisition contingent consideration.

[2] 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.

[3] In the fourth quarter ended December 31, 2012, the change in recognizing pension and postretirement benefit plans expense, as a result of the mark-to-market adjustments, 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.

[4] Restructuring and other, net includes $0.7 million of severance charges related to the headcount reductions of 9 people, of which $0.5 million and 7 people were in Systems Test Group, $0.2 million and 2 people were in Wireless Test.

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

[7] Restructuring and other, net includes $0.5 million of charges related to pension settlement and $3.3 million to the acquisition of LitePoint.

[8] In the fourth quarter ended December 31, 2011, the change in recognizing pension and postretirement benefit plans expense, as a result of the mark-to-market adjustments, decreased gross profit and net income by $2.4 million and $6.1 million, respectively. See Note B: "Accounting Policies" for a discussion of our accounting policy.

[9] Restructuring and other, net includes $1.4 million of charges related to the acquisition of LitePoint.

[10] Restructuring and other, net includes $0.3 million of severance charges related to headcount reductions of approximately 2 people in Semiconductor Test and $0.7 million related to pension settlement charges.

[11] Restructuring and other, net includes $0.8 million of severance charges related to headcount reductions of approximately 5 people in Semiconductor Test and $(0.4) million credit related to early exit of previously impaired leased facilities in Westford and North Reading, Massachusetts.

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

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

[14] Total business assets are directly attributable to each business. Corporate assets consist of cash and cash equivalents, marketable securities, unallocated fixed assets of support departments, common facilities and certain other assets.

[15] Corporate property additions and depreciation and amortization expense include items attributable to the unallocated fixed assets of support departments and common facilities.