Consolidated Statements of Redeemable Noncontrolling Interest and Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock, $1.00 par value	Capital in Excess of Par Value	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Items	Total Thermo Fisher Scientific Inc. Shareholders’ Equity	Noncontrolling Interests
Beginning Balance at Dec. 31, 2021	$ 122
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income/(loss)	(11)
Net income	5
Contributions from (distributions to) noncontrolling interests	(3)
Ending Balance at Apr. 02, 2022	113
Balance (in shares) at Dec. 31, 2021		439,000,000
Beginning Balance at Dec. 31, 2021	40,855	$ 439	$ 16,174	$ 35,431	$ (8,922)	$ (2,329)	$ 40,793	$ 62
Treasury stock beginning balance (in shares) at Dec. 31, 2021					45,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)		1,000,000
Issuance of shares under employees' and directors' stock plans	2	$ 1	40		$ (39)		2
Stock-based compensation	78		78				78
Purchases of company common stock (in shares)					3,000,000
Purchases of company common stock	(2,000)				$ (2,000)		(2,000)
Dividends declared	(118)			(118)			(118)
Net income	2,215			2,215			2,215
Other comprehensive items	(13)					(14)	(14)	1
Excise tax from stock repurchases	0
Contributions from (distributions to) noncontrolling interests	(1)							(1)
Balance (in shares) at Apr. 02, 2022		440,000,000
Treasury stock ending balance (in shares) at Apr. 02, 2022					48,000,000
Ending Balance at Apr. 02, 2022	41,018	$ 440	16,292	37,528	$ (10,961)	(2,343)	40,956	62
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	5
Beginning Balance at Dec. 31, 2022	116
Redeemable Noncontrolling Interest [Roll Forward]
Other comprehensive income/(loss)	3
Net income	4
Ending Balance at Apr. 01, 2023	123
Balance (in shares) at Dec. 31, 2022		441,000,000
Beginning Balance at Dec. 31, 2022	$ 44,032	$ 441	16,743	41,910	$ (12,017)	(3,099)	43,978	54
Treasury stock beginning balance (in shares) at Dec. 31, 2022	50,157,275				50,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans	$ 34		70		$ (36)		34
Stock-based compensation	76		76				76
Purchases of company common stock (in shares)					5,000,000
Purchases of company common stock	(3,000)				$ (3,000)		(3,000)
Dividends declared	(135)			(135)			(135)
Net income	1,288			1,289			1,289	(1)
Other comprehensive items	45					45	45
Excise tax from stock repurchases	$ 30				$ 30		30
Balance (in shares) at Apr. 01, 2023		441,000,000
Treasury stock ending balance (in shares) at Apr. 01, 2023	55,445,006				55,000,000
Ending Balance at Apr. 01, 2023	$ 42,310	$ 441	$ 16,889	$ 43,064	$ (15,083)	$ (3,054)	$ 42,257	$ 53
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 4