Condensed Consolidated Statement of Redeemable Noncontrolling Interest and Equity (Unaudited) - USD ($) $ in Millions	Total	Total Thermo Fisher Scientific Inc. Shareholders’ Equity	Common Stock, $1.00 par value	Capital in Excess of Par Value	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Items	Noncontrolling Interests
Beginning Balance at Dec. 31, 2022	$ 116
Redeemable Noncontrolling Interest [Roll Forward]
Net income/(loss)	8
Other comprehensive income/(loss)	(4)
Contributions from (distributions to) noncontrolling interests	(7)
Ending Balance at Jul. 01, 2023	113
Balance (in shares) at Dec. 31, 2022			441,000,000
Beginning Balance at Dec. 31, 2022	44,032	$ 43,978	$ 441	$ 16,743	$ 41,910	$ (12,017)	$ (3,099)	$ 54
Treasury stock beginning balance (in shares) at Dec. 31, 2022						50,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under stock plans	99	99		137		$ (38)
Stock-based compensation	150	150		150
Purchases of company common stock (in shares)						5,000,000
Purchases of company common stock	(3,000)	(3,000)				$ (3,000)
Dividends declared	(271)	(271)			(271)
Net income/(loss)	2,646	2,650			2,650			(4)
Other comprehensive items	175	175					175
Excise tax from stock repurchases	(29)	(29)				$ (29)
Balance (in shares) at Jul. 01, 2023			441,000,000
Treasury stock ending balance (in shares) at Jul. 01, 2023						55,000,000
Ending Balance at Jul. 01, 2023	43,802	43,752	$ 441	17,030	44,289	$ (15,084)	(2,924)	50
Beginning Balance at Apr. 01, 2023	123
Redeemable Noncontrolling Interest [Roll Forward]
Net income/(loss)	4
Other comprehensive income/(loss)	(7)
Contributions from (distributions to) noncontrolling interests	(7)
Ending Balance at Jul. 01, 2023	113
Balance (in shares) at Apr. 01, 2023			441,000,000
Beginning Balance at Apr. 01, 2023	42,310	42,257	$ 441	16,889	43,064	$ (15,083)	(3,054)	53
Treasury stock beginning balance (in shares) at Apr. 01, 2023						55,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under stock plans	65	65		67		$ (2)
Stock-based compensation	74	74		74
Dividends declared	(136)	(136)			(136)
Net income/(loss)	1,358	1,361			1,361			(3)
Other comprehensive items	130	130					130
Excise tax from stock repurchases	1	1				$ 1
Balance (in shares) at Jul. 01, 2023			441,000,000
Treasury stock ending balance (in shares) at Jul. 01, 2023						55,000,000
Ending Balance at Jul. 01, 2023	43,802	43,752	$ 441	17,030	44,289	$ (15,084)	(2,924)	50
Beginning Balance at Dec. 31, 2023	118
Redeemable Noncontrolling Interest [Roll Forward]
Net income/(loss)	10
Other comprehensive income/(loss)	(6)
Contributions from (distributions to) noncontrolling interests	(7)
Ending Balance at Jun. 29, 2024	115
Balance (in shares) at Dec. 31, 2023			442,000,000
Beginning Balance at Dec. 31, 2023	$ 46,724	46,735	$ 442	17,286	47,364	$ (15,133)	(3,224)	(11)
Treasury stock beginning balance (in shares) at Dec. 31, 2023	55,541,290					56,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under stock plans (in shares)			1,000,000
Issuance of shares under stock plans	$ 184	184	$ 1	209		$ (26)
Stock-based compensation	154	154		154
Purchases of company common stock (in shares)						6,000,000
Purchases of company common stock	(3,000)	(3,000)				$ (3,000)
Dividends declared	(298)	(298)			(298)
Net income/(loss)	2,874	2,875			2,875			(1)
Other comprehensive items	811	811					811
Contributions from (distributions to) noncontrolling interests	(1)							(1)
Excise tax from stock repurchases	$ (28)	(28)				$ (28)
Balance (in shares) at Jun. 29, 2024			443,000,000
Treasury stock ending balance (in shares) at Jun. 29, 2024	61,110,092					61,000,000
Ending Balance at Jun. 29, 2024	$ 47,419	47,432	$ 443	17,649	49,940	$ (18,187)	(2,413)	(12)
Beginning Balance at Mar. 30, 2024	119
Redeemable Noncontrolling Interest [Roll Forward]
Net income/(loss)	6
Other comprehensive income/(loss)	(3)
Contributions from (distributions to) noncontrolling interests	(7)
Ending Balance at Jun. 29, 2024	115
Balance (in shares) at Mar. 30, 2024			443,000,000
Beginning Balance at Mar. 30, 2024	45,504	45,516	$ 443	17,482	48,542	$ (18,186)	(2,764)	(12)
Treasury stock beginning balance (in shares) at Mar. 30, 2024						61,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under stock plans	81	81		83		$ (2)
Stock-based compensation	84	84		84
Dividends declared	(149)	(149)			(149)
Net income/(loss)	1,548	1,548			1,548
Other comprehensive items	351	351					351
Excise tax from stock repurchases	$ 1	1				$ 1
Balance (in shares) at Jun. 29, 2024			443,000,000
Treasury stock ending balance (in shares) at Jun. 29, 2024	61,110,092					61,000,000
Ending Balance at Jun. 29, 2024	$ 47,419	$ 47,432	$ 443	$ 17,649	$ 49,940	$ (18,187)	$ (2,413)	$ (12)