CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 29, 2025	Mar. 30, 2024
Comprehensive income/(loss)
Net income	$ 1,511	$ 1,331
Currency translation adjustment:
Currency translation adjustment (net of tax provision (benefit) of $(207) and $166)	360	456
Unrealized gains/(losses) on available-for-sale debt securities
Unrealized holding losses arising during the period (net of tax (provision) benefit of $0 and $0)	0	(1)
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 $0)	(3)	1
Amortization of net loss included in net periodic pension cost (net of tax (provision) benefit of $0 and $0)	1	0
Total other comprehensive income/(loss)	358	457
Comprehensive income/(loss)	1,869	1,788
Less: comprehensive income/(loss) attributable to noncontrolling interests and redeemable noncontrolling interest	8	1
Comprehensive income attributable to Thermo Fisher Scientific Inc.	$ 1,861	$ 1,787