CONSOLIDATED STATEMENTS OF REDEEMABLE NONCONTROLLING INTEREST AND EQUITY - USD ($) $ in Millions	Total	Total Thermo Fisher Scientific Inc. Shareholders’ Equity	Common Stock	Capital in Excess of Par Value	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Items	Noncontrolling Interests
Beginning Balance at Dec. 31, 2021	$ 122
Redeemable Noncontrolling Interest [Roll Forward]
Net income/(loss)	15
Other comprehensive income/(loss)	(6)
Contributions from (distributions to) noncontrolling interests	(15)
Ending Balance at Dec. 31, 2022	116
Balance (in shares) at Dec. 31, 2021			439,000,000
Beginning Balance at Dec. 31, 2021	40,855	$ 40,793	$ 439	$ 16,174	$ 35,431	$ (8,922)	$ (2,329)	$ 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 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)
Other comprehensive income/(loss)	(771)	(770)					(770)	(1)
Contributions from (distributions to) noncontrolling interests	(2)							(2)
Balance (in shares) at Dec. 31, 2022			441,000,000
Treasury stock ending balance (in shares) at Dec. 31, 2022						50,000,000
Ending Balance at Dec. 31, 2022	44,032	43,978	$ 441	16,743	41,910	$ (12,017)	(3,099)	54
Redeemable Noncontrolling Interest [Roll Forward]
Net income/(loss)	19
Other comprehensive income/(loss)	(3)
Contributions from (distributions to) noncontrolling interests	(14)
Ending Balance at Dec. 31, 2023	118
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under 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)
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
Treasury stock ending balance (in shares) at Dec. 31, 2023	55,541,290					56,000,000
Ending Balance at Dec. 31, 2023	$ 46,724	46,735	$ 442	17,286	47,364	$ (15,133)	(3,224)	(11)
Redeemable Noncontrolling Interest [Roll Forward]
Net income/(loss)	23
Other comprehensive income/(loss)	(6)
Contributions from (distributions to) noncontrolling interests	(14)
Ending Balance at Dec. 31, 2024	120
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of shares under stock plans (in shares)			2,000,000			0
Issuance of shares under stock plans	310	310	$ 2	376		$ (67)
Stock-based compensation	301	301		301
Purchases of company common stock (in shares)						7,000,000
Purchases of company common stock	(4,000)	(4,000)				$ (4,000)
Dividends declared	(596)	(596)			(596)
Net income/(loss)	6,315	6,335			6,335			(20)
Other comprehensive income/(loss)	527	527					527	0
Contributions from (distributions to) noncontrolling interests	(1)							(1)
Excise tax from stock repurchases	$ (26)	(26)				$ (26)
Balance (in shares) at Dec. 31, 2024			444,000,000
Treasury stock ending balance (in shares) at Dec. 31, 2024	63,066,906					63,000,000
Ending Balance at Dec. 31, 2024	$ 49,551	$ 49,584	$ 444	$ 17,962	$ 53,102	$ (19,226)	$ (2,697)	$ (33)