Change in Accounting Principle - Additional Information (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
Change In Accounting Principle
Net income before accounting changes																	$ 207,000,000
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
Earnings per share diluted before accounting charges																	$ 0.90
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

[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.