Revenue - Accounts Receivable, Unbilled Services, and Deferred Revenue (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Accounts receivable:
Accounts receivable, beginning balance	$ 304,916	$ 96,210
Additions	136,510	146,424
Deductions	(412,370)	(115,950)
Accounts receivable, ending balance	29,056	126,684
Allowance for doubtful accounts
Allowance for credit losses, beginning balance	(7,676)	(13,835)
Additions	0	0
Deductions	0	0
Allowance for credit losses, end balance	(7,676)	(13,835)
Deferred revenue
Deferred revenue, beginning balance	863,521	549,551
Additions	225,000	140,324
Deductions	(6,148)	(49)
Deferred revenue, ending balance	1,082,373	689,826
Revenue Recognition
Additions	0	0
Contract with customer, liability, deductions	6,148	$ 49
Joint Committee on Vaccination and Immunization (JCVI)
Deferred revenue
Deductions	(2,200)
Revenue Recognition
Contract with customer, liability, deductions	$ 2,200