Income Taxes - Additional Information (Detail) - USD ($) $ / shares in Units, $ 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		Sep. 30, 2018	[8]	Jul. 01, 2018	[9]	Apr. 01, 2018	[10]	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Taxes [Line Items]
Total (benefit) provision for income taxes	$ 23,811	[1],[2]	$ 15,873		$ 33,780		$ (15,159)		$ (32,662)	[6],[7]	$ 20,863		$ 18,975		$ 8,846			$ 58,304	$ 16,022	$ 266,720
Effective tax rate																		11.10%	3.40%	50.90%
Provisional amount of additional income tax expense									49,500								$ 186,000
Transition tax on mandatory deemed repatriation of foreign earnings																			$ 51,700	$ 161,000
Expense related to remeasurement of deferred tax assets and liabilities																				33,600
Expense (benefit) associated with impact of correlative adjustments on tax positions																			2,200
Tax savings due to the tax holiday																		$ 15,100	$ 11,900	$ 24,800
Tax savings due to the tax holiday, per share																		$ 0.08	$ 0.06	$ 0.12
Tax holiday expiration date																		December 31, 2020
Valuation allowance includes net deferred tax assets	77,177								69,852									$ 77,177	$ 69,852
Tax credit carryforwards, approximately																	108,400			$ 108,400
Tax credits carryforwards	79,480								69,091									79,480	69,091
Reduction in un recognized tax benefits	21,180								43,395								36,263	21,180	43,395	36,263	$ 38,958
Unrecognized tax benefits, if recognized would impact effective tax rate	12,700																	12,700
Unrecognized tax benefits, if recognized would impact deferred taxes	8,500																	8,500
Accrued interest and penalties	1,400								300									1,400	300
Interest and penalties related to income tax, expense (benefit)																		1,100	$ 100	100
Intercompany Cost Sharing Arrangement [Member]
Income Taxes [Line Items]
Total (benefit) provision for income taxes																		6,300
United States
Income Taxes [Line Items]
Tax credits carryforwards, business																	2,100			$ 2,100
Tax credit carryforward, expiration date																				2028
State and Local Jurisdiction
Income Taxes [Line Items]
Provisional amount of additional income tax expense																	186,000
Transition tax on mandatory deemed repatriation of foreign earnings									$ 51,700
Expense (benefit) associated with impact of correlative adjustments on tax positions																				$ 10,300
Tax credits carryforwards																	106,300			$ 106,300
Reduction in un recognized tax benefits	$ 21,200																	$ 21,200
State and Local Jurisdiction | Earliest Tax Year
Income Taxes [Line Items]
Tax credit carryforward, expiration date																				2020
State and Local Jurisdiction | Latest Tax Year
Income Taxes [Line Items]
Tax credit carryforward, expiration date																				2039
State and Local Jurisdiction | Do Not Expire
Income Taxes [Line Items]
Tax credits carryforwards																	$ 59,700			$ 59,700

[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.