Securities Sold Under Agreements to Repurchase - Remaining Contractual Maturities Of Repurchase Agreements (Detail) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	$ 2,259,728	$ 3,225,838
2 to 29 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	1,957,116	2,820,788
30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	301,112	404,800
Over 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	1,500	250
U.S. Treasury [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	259,082
U.S. Treasury [Member] | 2 to 29 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	259,082
U.S. Agencies [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	2,000,646	3,225,838
U.S. Agencies [Member] | 2 to 29 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	1,698,034	2,820,788
U.S. Agencies [Member] | 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	301,112	404,800
U.S. Agencies [Member] | Over 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	$ 1,500	$ 250