Goodwill and Acquired Client Relationships - Additional Information (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Intangible Assets
Goodwill impairment				$ 0
Estimated Future Amortization Expense of Finite-Lived Intangibles
Cash received in Veritable Transaction	$ 287,400,000
Transaction costs	6,600,000
Affiliate Transaction gain	133,100,000	$ 133,100,000	$ 0	$ 133,100,000	$ 0
After-tax net cash proceeds from the Veritable transaction	$ 225,100,000
Third Party
Estimated Future Amortization Expense of Finite-Lived Intangibles
Subsidary, ownership percentage, sold	1	1		1
Acquired Client Relationships
Estimated Future Amortization Expense of Finite-Lived Intangibles
Intangible impairments				$ 0
Acquired Client Relationships
Intangible Assets
Amortization and impairment expenses of intangible assets				37,500,000
Estimated Future Amortization Expense of Finite-Lived Intangibles
Finite-lived intangible, future amortization expense, remainder of fiscal year	$ 11,000,000	$ 11,000,000		11,000,000
Finite-lived intangible, future amortization expense in year one	30,000,000	30,000,000		30,000,000
Finite-lived intangible, future amortization expense in year two	25,000,000	25,000,000		25,000,000
Finite-lived intangible, future amortization expense in year three	25,000,000	25,000,000		25,000,000
Finite-lived intangible, future amortization expense in year four	25,000,000	25,000,000		25,000,000
Finite-lived intangible, future amortization expense in year five	$ 25,000,000	25,000,000		25,000,000
Acquired Client Relationships | Intangible amortization and impairments
Intangible Assets
Amortization and impairment expenses of intangible assets		$ 12,500,000	$ 12,200,000	$ 37,500,000	$ 36,900,000