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	108	$ 1	145		$ (38)		108
Stock-based compensation	102		102				102
Purchases of company common stock (in shares)					4
Purchases of company common stock	(2,000)				$ (2,000)		(2,000)
Dividends declared	(205)			(205)			(205)
Net income	4,166			4,165			4,165	1
Total other comprehensive items	177					177	177
Contribution from (distributions to) noncontrolling interests	36							36
Balance (in shares) at Jul. 03, 2021		438			45
Balance at Jul. 03, 2021	36,901	$ 438	15,826	32,076	$ (8,856)	(2,630)	36,854	47
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)					0
Issuance of shares under employees' and directors' stock plans	87		91		$ (4)		87
Stock-based compensation	51		51				51
Dividends declared	(102)			(102)			(102)
Net income	1,829			1,828			1,828	1
Total other comprehensive items	(68)					(68)	(68)
Contribution from (distributions to) noncontrolling interests	36							36
Balance (in shares) at Jul. 03, 2021		438			45
Balance at Jul. 03, 2021	36,901	$ 438	15,826	32,076	$ (8,856)	(2,630)	36,854	47
Redeemable Noncontrolling Interest, Balance at Dec. 31, 2021	122
Redeemable Noncontrolling Interest [Roll Forward]
Net income (loss) attributable to redeemable noncontrolling interest	9
Other comprehensive items attributable to redeemable noncontrolling interest	(7)
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(7)
Redeemable Noncontrolling Interest, Balance at Jul. 02, 2022	117
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	97	$ 1	138		$ (42)		97
Stock-based compensation	155		155				155
Purchases of company common stock (in shares)					3
Purchases of company common stock	(2,000)				$ (2,000)		(2,000)
Dividends declared	(236)			(236)			(236)
Net income	3,879			3,879			3,879
Total other comprehensive items	(395)					(395)	(395)
Contribution from (distributions to) noncontrolling interests	(1)							(1)
Balance (in shares) at Jul. 02, 2022		440			48
Balance at Jul. 02, 2022	42,354	$ 440	16,467	39,074	$ (10,964)	(2,724)	42,293	61
Redeemable Noncontrolling Interest, Balance at Apr. 02, 2022	113
Redeemable Noncontrolling Interest [Roll Forward]
Net income (loss) attributable to redeemable noncontrolling interest	4
Other comprehensive items attributable to redeemable noncontrolling interest	4
Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders	(4)
Redeemable Noncontrolling Interest, Balance at Jul. 02, 2022	117
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
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)					0
Issuance of shares under employees' and directors' stock plans	95		98		$ (3)		95
Stock-based compensation	77		77				77
Dividends declared	(118)			(118)			(118)
Net income	1,664			1,664			1,664
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest								(1)
Total other comprehensive items	(382)					(381)	(381)
Balance (in shares) at Jul. 02, 2022		440			48
Balance at Jul. 02, 2022	$ 42,354	$ 440	$ 16,467	$ 39,074	$ (10,964)	$ (2,724)	$ 42,293	$ 61