Consolidated Statement of Redeemable Noncontrolling Interest and Equity - 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
Redeemable noncontrolling interest, beginning balance at Dec. 31, 2020	$ 0
Redeemable Noncontrolling Interest [Roll Forward]
Recognition upon acquisition	122
Net income/(loss)	1
Other comprehensive income/(loss)	(1)
Redeemable noncontrolling interest, ending balance at Dec. 31, 2021	122
Balance (in shares) at Dec. 31, 2020			437,000,000
Balance at Dec. 31, 2020	34,517	$ 34,507	$ 437	$ 15,579	$ 28,116	$ (6,818)	$ (2,807)	$ 10
Balance, treasury stock (in shares) at Dec. 31, 2020						40,000,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)			2,000,000			1,000,000
Issuance of shares under stock plans	222	222	$ 2	324		$ (104)
Stock-based compensation	230	230		230
Purchases of company common stock (in shares)						4,000,000
Purchases of company common stock	(2,000)	(2,000)				$ (2,000)
Dividends declared	(410)	(410)			(410)
Net income/(loss)	7,727	7,725			7,725			2
Total other comprehensive income/(loss)	478	478					478
Contributions from (distributions to) noncontrolling interests	50							50
Excise tax from stock repurchases	0
Other	41	41		41
Balance (in shares) at Dec. 31, 2021			439,000,000
Balance at Dec. 31, 2021	40,855	40,793	$ 439	16,174	35,431	$ (8,922)	(2,329)	62
Balance, treasury stock (in shares) at Dec. 31, 2021						45,000,000
Redeemable Noncontrolling Interest [Roll Forward]
Net income/(loss)	15
Other comprehensive income/(loss)	(6)
Contributions from (distributions to) noncontrolling interests	(15)
Redeemable noncontrolling interest, ending balance at Dec. 31, 2022	116
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)			2,000,000
Issuance of shares under stock plans	169	169	$ 2	262		$ (95)
Stock-based compensation	307	307		307
Purchases of company common stock (in shares)						5,000,000
Purchases of company common stock	(3,000)	(3,000)				$ (3,000)
Dividends declared	(471)	(471)			(471)
Net income/(loss)	6,945	6,950			6,950			(5)
Total other comprehensive income/(loss)	(771)	(770)					(770)	(1)
Contributions from (distributions to) noncontrolling interests	(2)							(2)
Excise tax from stock repurchases	0
Balance (in shares) at Dec. 31, 2022			441,000,000
Balance at Dec. 31, 2022	$ 44,032	43,978	$ 441	16,743	41,910	$ (12,017)	(3,099)	54
Balance, treasury stock (in shares) at Dec. 31, 2022	50,157,275					50,000,000
Redeemable Noncontrolling Interest [Roll Forward]
Net income/(loss)	$ 19
Other comprehensive income/(loss)	(3)
Contributions from (distributions to) noncontrolling interests	(14)
Redeemable noncontrolling interest, ending balance at Dec. 31, 2023	118
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under employees' and directors' stock plans (in shares)			1,000,000			1,000,000
Issuance of shares under stock plans	178	178	$ 1	265		$ (88)
Stock-based compensation	278	278		278
Purchases of company common stock (in shares)						5,000,000
Purchases of company common stock	(3,000)	(3,000)				$ (3,000)
Dividends declared	(541)	(541)			(541)
Net income/(loss)	5,936	5,995			5,995			(59)
Total other comprehensive income/(loss)	(130)	(125)					(125)	(5)
Contributions from (distributions to) noncontrolling interests	(1)							(1)
Excise tax from stock repurchases	(28)	(28)				(28)
Balance (in shares) at Dec. 31, 2023			442,000,000
Balance at Dec. 31, 2023	$ 46,724	$ 46,735	$ 442	$ 17,286	$ 47,364	$ (15,133)	$ (3,224)	$ (11)
Balance, treasury stock (in shares) at Dec. 31, 2023	55,541,290					56,000,000