Goodwill and Acquired Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2019		Sep. 29, 2019	[3]	Jun. 30, 2019	[4]	Mar. 31, 2019	[5]	Dec. 31, 2018	[6],[7]	Sep. 30, 2018	[8]	Jul. 01, 2018	[9]	Apr. 01, 2018	[10]	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Line Items]
Acquired intangible assets amortization	$ 9,784	[1],[2]	$ 9,647		$ 10,083		$ 10,634		$ 10,558		$ 11,142		$ 9,793		$ 7,698		$ 40,147	$ 39,191	$ 30,530
MiR Reporting Unit Percentage	14.00%																14.00%
MiR Goodwill Amount	$ 123,600																$ 123,600

[1] Restructuring and other includes a $5.8 million gain for the decrease in the fair value adjustment to the MiR acquisition contingent consideration, partially offset by a $3.0 million fair value adjustment to increase the AutoGuide acquisition contingent consideration, $0.5 million of employee severance charges and $0.2 million of acquisition related expenses and compensation.

[2] Teradyne recorded pension and post retirement net actuarial losses of $7.7 million for the fourth quarter in 2019. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.

[3] Restructuring and other includes a $7.8 million gain for the decrease in the fair value of MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.

[4] Restructuring and other includes a $11.7 million gain for the decrease in the fair value of the MiR contingent consideration liability, partially offset by $0.8 million of employee severance charges and $0.5 million of acquisition related expenses and compensation.

[5] Restructuring and other includes a $3.0 million fair value adjustment to increase the MiR acquisition contingent consideration, $1.3 million of acquisition related expenses and compensation and $0.8 million of employee severance charges.

[6] Restructuring and other includes a $17.7 million fair value adjustment to increase the MiR acquisition contingent consideration, $0.8 million of employee severance charges, and $0.5 million acquisition related expenses and compensation, partially offset by a $7.4 million gain for the decrease in the fair value of the Universal Robots contingent consideration liability.

[7] Teradyne recorded pension and post retirement net actuarial gains of $3.5 million for the fourth quarter in 2018. See Note B: “Accounting Policies” for a discussion of Teradyne’s accounting policy.

[8] Restructuring and other includes $1.7 million of employee severance charges, $0.8 million of acquisition related expenses and compensation, partially offset by a $0.8 million gain for the decrease in the fair value of the Universal Robots contingent consideration liability.

[9] Restructuring and other includes a $5.0 million gain for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $3.9 million of employee severance charges and $0.8 million of acquisition related expenses and compensation.

[10] Restructuring and other includes a $3.5 million gain for the decrease in the fair value of the Universal Robots contingent consideration liability, partially offset by $2.5 million of acquisition related expenses and compensation and $2.4 million of employee severance charges.