Consolidated Statement of Redeemable Noncontrolling Interest and Equity (Unaudited) - USD ($) shares in Millions, $ in Millions	Total	Common Stock, $1.00 par value	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Items [Member]	Total Thermo Fisher Scientific Inc. Shareholders' Equity	Noncontrolling Interest
Balance (in shares) at Dec. 31, 2020		437			40
Balance at Dec. 31, 2020	$ 34,517	$ 437	$ 15,579	$ 28,116	$ (6,818)	$ (2,807)	$ 34,507	$ 10
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)		1			1
Issuance of shares under employees' and directors' stock plans	21	$ 1	54		$ (34)		21
Stock-based compensation	51		51				51
Purchases of company common stock (in shares)					4
Purchases of company common stock	(2,000)				$ (2,000)		(2,000)
Dividends declared	(103)			(103)			(103)
Net income	2,337			2,337			2,337
Other comprehensive items	245					245	245
Balance (in shares) at Apr. 03, 2021		438			45
Balance at Apr. 03, 2021	35,068	$ 438	15,684	30,350	$ (8,852)	(2,562)	35,058	10
Redeemable Noncontrolling Interest, Balance at Dec. 31, 2021	122
Redeemable Noncontrolling Interest [Roll Forward]
Net income (loss) attributable to redeemable noncontrolling interest	5
Other comprehensive items attributable to redeemable noncontrolling interest	(11)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(3)
Redeemable Noncontrolling Interest, Balance at Apr. 02, 2022	113
Balance (in shares) at Dec. 31, 2021		439			45
Balance at Dec. 31, 2021	40,855	$ 439	16,174	35,431	$ (8,922)	(2,329)	40,793	62
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)		1			0
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
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
Contribution from (distributions to) noncontrolling interests	(1)							(1)
Balance (in shares) at Apr. 02, 2022		440			48
Balance at Apr. 02, 2022	$ 41,018	$ 440	$ 16,292	$ 37,528	$ (10,961)	$ (2,343)	$ 40,956	$ 62