Summary of Significant Accounting Policies - Summary of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022	Sep. 30, 2022
Accounting Policies [Abstract]
Due from the FRB	$ 3,472,524		$ 1,639,182
Cash and due from banks	454,705	$ 500,682	371,336
Cash and cash equivalents at end of period	$ 3,927,229		$ 2,010,518