Acquisitions - Narrative (Details) £ / shares in Units, $ in Thousands, £ in Millions			3 Months Ended		12 Months Ended
	Jan. 23, 2023 USD ($) employee	Jan. 23, 2023 GBP (£) employee	Dec. 31, 2023 USD ($)	Jan. 01, 2023 USD ($)	Oct. 01, 2023 USD ($) employee program	Oct. 02, 2022 USD ($)	Sep. 23, 2022 £ / shares
Business Acquisition [Line Items]
Pence per share expected to be acquired | £ / shares							£ 2.22
Acquisition and integration expenses			$ 0	$ 3,761
Minimum
Business Acquisition [Line Items]
Significant unobservable input, earn-out period			3 years
Minimum | Existing customer contracts
Business Acquisition [Line Items]
Useful life of intangible assets			1 year
Maximum
Business Acquisition [Line Items]
Significant unobservable input, earn-out period			5 years
Maximum | Existing customer contracts
Business Acquisition [Line Items]
Useful life of intangible assets			12 years
RPS Group PLC
Business Acquisition [Line Items]
Number of employees | employee	5,000	5,000
Total purchase price	$ 784,000	£ 633
Acquisition and integration expenses					$ 33,200
Net purchase price	675,000
RPS Group PLC | Foreign Exchange Forward
Business Acquisition [Line Items]
Foreign currency forward contract, asset fair value	$ 109,300					$ 19,900
Amyx, Inc.
Business Acquisition [Line Items]
Number of employees | employee					500
Total purchase price					$ 120,900
Number of government programs acquired | program					30
Payables related to promissory note					$ 100,000
Receivables (payables) related to estimated post-closing adjustments					8,700
Contingent earn-out liability					12,200
Aggregate maximum of contingent consideration					$ 25,000
All acquisitions
Business Acquisition [Line Items]
Aggregate maximum of contingent consideration			$ 92,253	$ 120,882