Consolidated Statement of Redeemable Noncontrolling Interest and Equity - USD ($) shares in Millions, $ in Millions	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock, $1.00 par value	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Retained Earnings [Member] Cumulative Effect, Period of Adoption, Adjustment [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Items [Member]	Total Thermo Fisher Scientific Inc. Shareholders' Equity	Total Thermo Fisher Scientific Inc. Shareholders' Equity Cumulative Effect, Period of Adoption, Adjustment [Member]	Noncontrolling Interests
Balance (in shares) at Dec. 31, 2018			432				29
Balance at Dec. 31, 2018	$ 27,594	$ 4	$ 432	$ 14,621	$ 18,696	$ 4	$ (3,665)	$ (2,498)	$ 27,586	$ 4	$ 8
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)			2				1
Issuance of shares under employees' and directors' stock plans	193		$ 2	262			$ (71)		193
Stock-based compensation	181			181					181
Purchases of company common stock (in shares)							6
Purchases of company common stock	(1,500)						$ (1,500)		(1,500)
Dividends declared	(304)				(304)				(304)
Net income	3,698				3,696				3,696		2
Other comprehensive items	(180)							(181)	(181)		1
Contributions from (distributions to) noncontrolling interests	(2)										(2)
Balance (in shares) at Dec. 31, 2019			434				36
Balance at Dec. 31, 2019	29,684	$ (1)	$ 434	15,064	22,092	$ (1)	$ (5,236)	(2,679)	29,675	$ (1)	9
Redeemable Noncontrolling Interest, Balance at Dec. 31, 2020	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)			3				0
Issuance of shares under employees' and directors' stock plans	240		$ 3	319			$ (82)		240
Stock-based compensation	196			196					196
Purchases of company common stock (in shares)							4
Purchases of company common stock	(1,500)						$ (1,500)		(1,500)
Dividends declared	(350)				(350)				(350)
Net income	6,377				6,375				6,375		2
Other comprehensive items	(128)							(128)	(128)
Contributions from (distributions to) noncontrolling interests	(1)										(1)
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
Redeemable Noncontrolling Interest [Roll Forward]
Noncontrolling Interest, Increase from Business Combination	122
Net income (loss) attributable to redeemable noncontrolling interest	1
Other comprehensive items attributable to redeemable noncontrolling interest	(1)
Redeemable Noncontrolling Interest, Balance at Dec. 31, 2021	122
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)			2				1
Issuance of shares under employees' and directors' stock plans	222		$ 2	324			$ (104)		222
Stock-based compensation	230			230					230
Purchases of company common stock (in shares)							4
Purchases of company common stock	(2,000)						$ (2,000)		(2,000)
Dividends declared	(410)				(410)				(410)
Net income	7,727				7,725				7,725		2
Other comprehensive items	478							478	478
Contributions from (distributions to) noncontrolling interests	50										50
Other	41			41					41
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