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v3.21.2

Debt - Additional Information (Detail) $ / shares in Units, shares in Millions |  |  |  | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | --- | --- | ---
Nov. 05, 2021 USD ($) | May 01, 2020 USD ($) | Dec. 12, 2016 USD ($) Customer $ / shares shares | Dec. 31, 2021 USD ($) | Oct. 03, 2021 USD ($) $ / shares | Oct. 03, 2021 USD ($) $ / shares shares | Sep. 27, 2020 USD ($) shares | Dec. 31, 2020 USD ($) | Nov. 04, 2021
Debt Instrument |  |  |  |  |  |  |  |  |
Repurchase of common stock |  |  |  |  |  | $ 406,180,000 | $ 88,465,000 |  |
Repurchase of stock, shares | shares |  |  |  |  |  | 3.3 | 1.5 |  |
Line of Credit Facility, Maximum Borrowing Capacity |  | $ 400,000,000.0 |  |  |  |  |  |  |
Line of Credit Facility, Capacity Available for Specific Purpose Other than for Trade Purchases |  | $ 150,000,000.0 |  |  |  |  |  |  |
Line of Credit Facility, Interest Rate Description |  | The interest rates applicable to loans under the Credit Facility are, at Teradyne’s option, equal to either a base rate plus a margin ranging from 0.50% to 1.25% per annum or LIBOR, a minimum of 0.75%, plus a margin ranging from 1.50% to 2.25% per annum, based on the consolidated leverage ratio of Teradyne. In addition, Teradyne will pay a commitment fee on the unused portion of the commitments under the Credit Facility ranging from 0.25% to 0.40% per annum, based on the then applicable consolidated leverage ratio. |  |  |  |  |  |  |
Term of revolving credit facility |  | 3 years |  |  |  |  |  |  |
Convertible common shares |  |  |  |  | $ 235,200,000 | $ 302,000,000.0 |  |  |
Other (income) expense [Member] |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |
Gain loss on debt conversion |  |  |  |  | 20,200,000 | 25,400,000 |  |  |
Convertible Common Shares [Member] |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |
Shares Issued, Stock Options Exercised |  |  |  |  |  | 7,200,000 |  |  |
Subsequent Event [Member] | Convertible Common Shares [Member] |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |
Increase in debt principal, Additional conversion |  |  |  | $ 41,000,000.0 |  |  |  |  |
Collateral Pledged [Member] |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |
Line of Credit Facility, Interest Rate Description |  | 65 |  |  |  |  |  |  |
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  | $ 460,000,000.0 |  | $ 157,972,000 | 157,972,000 |  | $ 459,971,000 |
Debt instrument, interest rate, stated percentage |  |  | 1.25% |  |  |  |  |  | 1.25%
Debt instrument, net proceeds after issuance costs |  |  | $ 450,800,000 |  |  |  |  |  |
Payment for net cost of convertible note hedges net of warrant proceeds |  |  | 33,000,000.0 |  |  | $ 33,000,000.0 |  |  |
Repurchase of common stock |  |  | $ 50,100,000 |  |  |  |  |  |
Repurchase of stock, shares | shares |  |  | 2.0 |  |  |  |  |  |
Senior notes maturity date |  |  | Dec. 15, 2023 |  |  |  |  |  |
Debt instrument, frequency of periodic payment |  |  | payable semiannually in arrears on June 15 and December 15 of each year |  |  |  |  |  |
Debt instrument, date of first required payment |  |  | Jun. 15, 2017 |  |  |  |  |  |
Debt instrument, conversion option expiration date |  |  | Sep. 15, 2023 |  |  |  |  |  |
Debt instrument conversion price | $ / shares |  |  | $ 31.53 |  | $ 31.53 | $ 31.53 |  |  |
Shares that would be issued upon conversion | shares |  |  | 14.6 |  |  | 8.7 |  |  |
Strike price per share of warrant | $ / shares |  |  |  |  |  | $ 39.56 |  |  |
Debt instrument, convertible, carrying amount of equity component |  |  |  |  | $ 100,800,000 | $ 100,800,000 | $ 100,800,000 |  |
Debt instrument, effective annual interest rate |  |  |  |  | 5.00% | 5.00% |  |  |
Financing cost |  |  |  |  | $ 900,000 | $ 900,000 | $ 7,200,000 |  |
Debt issuance costs, amortization period |  |  |  |  |  |  | 7 years |  |
Unamortized discount |  |  |  |  | 13,000,000.0 | 13,000,000.0 |  |  |
Debt Instrument, convertible, remaining discount amortization period |  |  |  |  |  |  |  | 2 years 3 months 18 days |
Value of notes converted |  |  |  |  |  | 1,364,600,000 |  |  |
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Subsequent Event [Member] |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |
Debt instrument conversion converted instrument amount | $ 343,000,000.0 |  |  |  |  |  |  |  |
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Conversion option one |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |
Trading days measurement period | Customer |  |  | 20 |  |  |  |  |  |
Consecutive trading days measurement period | Customer |  |  | 30 |  |  |  |  |  |
Percentage of conversion price |  |  | 130.00% |  |  |  |  |  |
1.25% Convertible Senior Unsecured Notes Due December 15, 2023 | Conversion option two |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |
Aggregate principal amount |  |  | $ 1,000 |  |  |  |  |  |
Trading days measurement period | Customer |  |  | 5 |  |  |  |  |  |
Consecutive trading days measurement period | Customer |  |  | 5 |  |  |  |  |  |
Percentage of closing sale price of common stock and conversion rate product |  |  | 98.00% |  |  |  |  |  |
Revolving Credit Facility |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |
Revolving credit facility costs incurred |  |  |  |  | $ 3,500,000 | $ 3,500,000 |  |  |

X
- Definition Antidilution adjustments of convertible note hedges. + References No definition available. + Details
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- Definition Debt instrument issuance costs amortization period. + References No definition available. + Details
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- Definition Gain loss on debt conversion. + References No definition available. + Details
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- Definition The value of the financial instrument(s) that the original debt is being converted into in a noncash (or part noncash) transaction. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586 + Details
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- Definition Expiration, mandatory redemption, or due date, in YYYY-MM-DD format, of the financial instrument issued in exchange for the original debt being converted in a noncash or part noncash transaction. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4304-108586 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=123431023&loc=d3e4332-108586 + Details
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- Definition The price per share of the conversion feature embedded in the debt instrument. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 5 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123466204&loc=SL6031898-161870 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 + Details
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