Schedule of Provision (Benefit) for Income Taxes from Operations (Detail) - USD ($) $ in Thousands	3 Months Ended																12 Months Ended
	Dec. 31, 2019	[1],[2]	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
Income Tax Disclosure [Line Items]
Current, U.S. Federal																	$ 19,297	$ (59,122)	$ 162,679
Current, Non-U.S.																	52,810	45,083	64,313
Current, State																	(4,347)	1,721	2,623
Current, Total																	67,760	(12,318)	229,615
Deferred, U.S. Federal																	(4,522)	29,252	43,687
Deferred, Non-U.S.																	(8,007)	(1,243)	(6,476)
Deferred, State																	3,073	331	(106)
Deferred, Total																	(9,456)	28,340	37,105
Total provision (benefit) for income taxes	$ 23,811		$ 15,873		$ 33,780		$ (15,159)		$ (32,662)		$ 20,863		$ 18,975		$ 8,846		$ 58,304	$ 16,022	$ 266,720

[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.