Securities Sold Under Agreements to Repurchase - Remaining Contractual Maturities Of Repurchase Agreements (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	$ 2,754,743	$ 3,225,838
Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	2,284,715
2 to 29 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	171,106	2,820,788
30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	298,422	404,800
Over 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	500	250
U.S. Treasury [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	74,523
U.S. Treasury [Member] | Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	74,523
U.S. Agencies [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	2,680,220	3,225,838
U.S. Agencies [Member] | Overnight [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	2,210,192
U.S. Agencies [Member] | 2 to 29 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	171,106	2,820,788
U.S. Agencies [Member] | 30 to 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	298,422	404,800
U.S. Agencies [Member] | Over 90 Days [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Total repurchase agreements	$ 500	$ 250