Accounts Payable, Accrued Expenses and Other Liabilities - Components of Other Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Payables and Accruals [Abstract]
Accrued compensation	$ 111,988	$ 112,528
Payroll and other taxes payable	63,822	59,277
Financial guarantee liability	29,802	28,551	$ 27,729
Deferred rent	6,163	6,381
Contingent consideration	25,910	25,740
Other	9,110	9,264
Total	$ 246,795	$ 241,741