Statements of Operations (Detail) (USD $)	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
Quarterly Financial Information [Line Items]
Products	$ 179,063,000	[1],[2],[3]	$ 393,037,000	[4]	$ 480,578,000	[5]	$ 330,891,000	[6]	$ 228,212,000	[7],[8]	$ 274,944,000	[9]	$ 341,316,000	[10]	$ 315,719,000	[11]	$ 1,383,569,000		$ 1,160,191,000		$ 1,330,942,000
Services	69,341,000	[1],[2],[3]	70,357,000	[4]	67,706,000	[5]	65,777,000	[6]	68,780,000	[7],[8]	69,445,000	[9]	69,203,000	[10]	61,442,000	[11]	273,181,000		268,870,000		235,220,000
Total net revenues	248,404,000	[1],[2],[3]	463,394,000	[4]	548,284,000	[5]	396,668,000	[6]	296,992,000	[7],[8]	344,389,000	[9]	410,519,000	[10]	377,161,000	[11]	1,656,750,000		1,429,061,000		1,566,162,000
Cost of products	92,599,000	[1],[2],[3]	169,782,000	[4]	206,498,000	[5]	174,001,000	[6]	127,477,000	[7],[8]	138,088,000	[9]	160,491,000	[10]	152,880,000	[11]	642,881,000		578,936,000		589,891,000
Cost of services	30,400,000	[1],[2],[3]	33,412,000	[4]	32,280,000	[5]	31,741,000	[6]	35,548,000	[7],[8]	35,927,000	[9]	35,438,000	[10]	31,389,000	[11]	127,832,000		138,302,000		118,688,000
Total cost of revenues	122,999,000	[1],[2],[3]	203,194,000	[4]	238,778,000	[5]	205,742,000	[6]	163,025,000	[7],[8]	174,015,000	[9]	195,929,000	[10]	184,269,000	[11]	770,713,000		717,238,000		708,579,000
Gross profit	125,405,000	[1],[2],[3]	260,200,000	[4]	309,506,000	[5]	190,926,000	[6]	133,967,000	[7],[8]	170,374,000	[9]	214,590,000	[10]	192,892,000	[11]	886,037,000		711,823,000		857,583,000
Engineering and development	61,660,000	[1],[2],[3]	63,055,000	[4]	66,532,000	[5]	60,135,000	[6]	56,364,000	[7],[8]	45,896,000	[9]	48,394,000	[10]	47,144,000	[11]	251,382,000		197,798,000		191,863,000
Selling and administrative	70,436,000	[1],[2],[3]	69,921,000	[4]	73,366,000	[5]	67,777,000	[6]	64,943,000	[7],[8]	54,775,000	[9]	58,028,000	[10]	57,573,000	[11]	281,500,000		235,319,000		225,333,000
Acquired intangible assets amortization	18,221,000	[1],[2],[3]	18,429,000	[4]	18,429,000	[5]	18,429,000	[6]	19,129,000	[7],[8]	6,754,000	[9]	7,291,000	[10]	7,291,000	[11]	73,508,000		40,465,000		29,250,000
Restructuring and other, net	(317,000)	[1],[2],[3]	683,000	[4]	(6,262,000)	[5]	(1,825,000)	[6]	3,824,000	[7],[8]	1,465,000	[9]	1,041,000	[10]	413,000	[11]	(7,721,000)		6,743,000		(3,800,000)
Total operating expenses	150,000,000	[1],[2],[3]	152,088,000	[4]	152,065,000	[5]	144,516,000	[6]	144,260,000	[7],[8]	108,890,000	[9]	114,754,000	[10]	112,421,000	[11]	598,669,000		480,325,000		442,646,000
Income (loss) from operations	(24,595,000)	[1],[2],[3]	108,112,000	[4]	157,441,000	[5]	46,410,000	[6]	(10,293,000)	[7],[8]	61,484,000	[9]	99,836,000	[10]	80,471,000	[11]	287,368,000		231,498,000		414,937,000
Interest income	1,256,000	[1],[2],[3]	1,067,000	[4]	874,000	[5]	893,000	[6]	878,000	[7],[8]	3,049,000	[9]	1,403,000	[10]	1,287,000	[11]	4,090,000		6,617,000		5,861,000
Interest expense and other	(6,946,000)	[1],[2],[3]	(6,154,000)	[4]	(6,323,000)	[5]	(6,059,000)	[6]	(6,134,000)	[7],[8]	(6,068,000)	[9]	(5,316,000)	[10]	(6,176,000)	[11]	(25,482,000)		(23,694,000)		(24,451,000)
Income (loss) from continuing operations before income taxes	(30,285,000)	[1],[2],[3]	103,025,000	[4]	151,992,000	[5]	41,244,000	[6]	(15,549,000)	[7],[8]	58,465,000	[9]	95,923,000	[10]	75,582,000	[11]	265,976,000	[12],[13]	214,421,000	[12],[13]	396,347,000	[12],[13]
(Benefit) provision for income taxes	(13,742,000)	[1],[2],[3]	14,384,000	[4]	40,605,000	[5]	7,680,000	[6]	(144,620,000)	[7],[8]	1,759,000	[9]	7,839,000	[10]	5,486,000	[11]	48,927,000		(129,536,000)		16,655,000
Income (loss) from continuing operations	(16,543,000)	[1],[2],[3]	88,641,000	[4]	111,387,000	[5]	33,564,000	[6]	129,071,000	[7],[8]	56,706,000	[9]	88,084,000	[10]	70,096,000	[11]	217,049,000		343,957,000		379,692,000
Income (loss) from discontinued operations before income taxes															1,278,000	[11]			1,278,000		5,406,000
Income (loss) from discontinued operations															1,545,000	[11]			1,545,000		5,128,000
Net income	(16,543,000)	[1],[2],[3]	88,641,000	[4]	111,387,000	[5]	33,564,000	[6]	129,071,000	[7],[8]	56,706,000	[9]	87,252,000	[10]	96,844,000	[11]	217,049,000		369,873,000		384,820,000
Income (loss) per common share from continuing operations-basic	$ (0.09)	[1],[2],[3]	$ 0.47	[4]	$ 0.60	[5]	$ 0.18	[6]	$ 0.70	[7],[8]	$ 0.31	[9]	$ 0.48	[10]	$ 0.38	[11]	$ 1.16		$ 1.86		$ 2.11
Income (loss) per common share from continuing operations-diluted	$ (0.09)	[1],[2],[3]	$ 0.39	[4]	$ 0.49	[5]	$ 0.15	[6]	$ 0.58	[7],[8]	$ 0.26	[9]	$ 0.38	[10]	$ 0.30	[11]	$ 0.94		$ 1.52		$ 1.73
Net income (loss) per common share-basic	$ (0.09)	[1],[2],[3]	$ 0.47	[4]	$ 0.60	[5]	$ 0.18	[6]	$ 0.70	[7],[8]	$ 0.31	[9]	$ 0.47	[10]	$ 0.52	[11]	$ 1.16		$ 2.00		$ 2.14
Net income (loss) per common share-diluted	$ (0.09)	[1],[2],[3]	$ 0.39	[4]	$ 0.49	[5]	$ 0.15	[6]	$ 0.58	[7],[8]	$ 0.26	[9]	$ 0.38	[10]	$ 0.42	[11]	$ 0.94		$ 1.63		$ 1.75
Income tax provision (benefit) errors	200,000																48,927,000		(125,225,000)		16,933,000
Decreased gross profit									2,400,000
Decrease in net income									6,100,000
Income tax provision															(267,000)	[11]			267,000		(278,000)
Gain (Loss) on disposal of discontinued operations (net of income tax provision of $4,578)													(832,000)	[10]	25,203,000	[11]			24,371,000
Defined Benefit Pension And Post Retirement Benefit Plans
Quarterly Financial Information [Line Items]
Decreased gross profit	8,100,000
Decrease in net income	$ 18,300,000

[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.