CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 28, 2026	Mar. 29, 2025
Comprehensive income/(loss)
Net income	$ 1,656	$ 1,511
Cumulative translation adjustment:
Cumulative translation adjustment (net of tax provision (benefit) of $27 and $(207))	(58)	360
Unrealized gains/(losses) on hedging instruments:
Reclassification adjustment for losses included in net income (net of tax (provision) benefit of $0 and $0)	1	1
Pension and other postretirement benefit liability adjustments:
Pension and other postretirement benefit liability adjustments arising during the period (net of tax (provision) benefit of $(1) and $1)	2	(3)
Amortization of net loss included in net periodic pension cost (net of tax (provision) benefit of $0 and $0)	1	1
Total other comprehensive income/(loss)	(55)	358
Comprehensive income/(loss)	1,601	1,869
Less: comprehensive income/(loss) attributable to noncontrolling interests and redeemable noncontrolling interest	(1)	8
Comprehensive income attributable to Thermo Fisher Scientific Inc.	$ 1,602	$ 1,861