Intangible assets - Schedule of Carrying Amount of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Cost
Total cost	$ 5,206,220	$ 5,207,518
Accumulated amortization	(2,009,516)	(1,873,663)
Impairment	0	(86,737)
Net book value	3,196,704	3,247,118
Customer relationships
Cost
Total cost	4,133,727	4,134,478
Order backlog
Cost
Total cost	545,727	546,054
Trade names & brands
Cost
Total cost	204,700	204,721
Patient database
Cost
Total cost	170,484	170,511
Technology assets
Cost
Total cost	$ 151,582	$ 151,754

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Name Accounting Standards Codification
-Section 55
-Paragraph 40
-SubTopic 30
-Topic 350
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482640/350-30-55-40

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 10
-Name Accounting Standards Codification
-Section S45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480265/350-10-S45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 350
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482665/350-30-50-2

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(16))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1

Name:	us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant