Commitments and Contingencies - Commitments and Contingent Liabilities Outstanding (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Commitments to extend credit
Home equity lines of credit	$ 8,299,310	$ 8,261,560
Commercial real estate loans to be sold	587,996	348,701
Other commercial real estate	6,217,720	5,776,116
Residential real estate loans to be sold	198,610	31,208
Other residential real estate	427,954	505,121
Commercial and other	32,964,637	32,625,840
Standby letters of credit	2,433,702	2,376,644
Commercial letters of credit	35,038	65,066
Financial guarantees and indemnification contracts	3,936,632	4,022,432
Commitments to sell real estate loans	$ 1,193,328	$ 533,458