CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 28, 2025	Jun. 29, 2024	Jun. 28, 2025	Jun. 29, 2024
Comprehensive income/(loss)
Net income	$ 1,618	$ 1,553	$ 3,130	$ 2,885
Currency translation adjustment:
Currency translation adjustment (net of tax provision (benefit) of $(207), $88, $(414) and $255)	(447)	346	(87)	802
Unrealized gains/(losses) on available-for-sale debt securities
Unrealized holding losses arising during the period (net of tax (provision) benefit of $0, $0, $0 and $0)	0	0	0	(1)
Unrealized gains/(losses) on hedging instruments:
Reclassification adjustment for losses included in net income (net of tax (provision) benefit of $0, $0, $0 and $0)	1	1	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 $3, $0, $4 and $0)	(8)	0	(11)	1
Amortization of net loss included in net periodic pension cost (net of tax (provision) benefit of $1, $0, $1 and $0)	3	1	4	1
Total other comprehensive income/(loss)	(451)	348	(93)	805
Comprehensive income/(loss)	1,168	1,901	3,037	3,689
Less: comprehensive income/(loss) attributable to noncontrolling interests and redeemable noncontrolling interest	4	3	12	3
Comprehensive income attributable to Thermo Fisher Scientific Inc.	$ 1,164	$ 1,899	$ 3,025	$ 3,686