Securities Purchased Under Agreements to Resell and Securities Sold Under Agreements to Repurchase - Repurchase Agreements Accounted for as Secured Borrowings (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements accounted for as secured borrowings	$ 65,374.8	$ 62,860.2
U.S. Treasury and Agency Securities
Assets Sold under Agreements to Repurchase [Line Items]
Repurchase agreements accounted for as secured borrowings	$ 65,374.8	$ 62,860.2