v3.26.3
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 27, 2026
Sep. 28, 2025
Sep. 27, 2026
Sep. 28, 2025
Statement of Comprehensive Income [Abstract]        
Consolidated net income $ 347,739 $ 119,558 $ 1,121,533 $ 296,827
Other comprehensive income (loss), net of tax:        
Foreign currency translation adjustment, net of tax of $0, $0, $0, and $0, respectively (19) (4,351) (31,396) 117,966
Available-for-sale marketable securities:        
Unrealized (losses) gains on marketable securities arising during period, net of tax of $(609), $201, $(677), and $316, respectively (5,145) 739 (4,918) 1,324
Less: Reclassification adjustment for (gains) losses included in net income, net of tax of $(2), $0, $10, $27, respectively (8) 0 5 89
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Total (5,153) 739 (4,913) 1,413
Cash flow hedges:        
Unrealized (losses) gains arising during period, net of tax of $(32), $0, $(32), and $(109), respectively (114) 0 (114) (381)
Less: Reclassification adjustment for losses (gains) included in net income, net of tax of $20, $0, $20, and $(100), respectively 69 0 69 (350)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent (45) 0 (45) (731)
Defined benefit postretirement plan:        
Amortization of prior service credit, net of tax of $0, $0, $(1), and $(1), respectively (1) (2) (3) (6)
Other comprehensive income (loss) (5,218) (3,614) (36,357) 118,642
Consolidated comprehensive income 342,521 115,944 1,085,176 415,469
Less: comprehensive income attributable to redeemable noncontrolling interests 5,332 0 5,684 0
Total comprehensive income attributable to Teradyne $ 337,189 $ 115,944 $ 1,079,492 $ 415,469