Securities - Summary Of Debt Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	$ 8,587,179	$ 3,125,184
Unrealized Gains	36,492	62,549
Unrealized Losses	(112,447)	(3,872)
Fair Value	8,511,224	3,183,861
Government-sponsored residential mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	5,577,292	2,106,658
Unrealized Gains	17,918	42,142
Unrealized Losses	(70,502)	0
Fair Value	5,524,708	2,148,800
Government-sponsored commercial mortgage-backed securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,420,748	17,054
Unrealized Gains	760	27
Unrealized Losses	(12,640)	0
Fair Value	1,408,868	17,081
U.S. Agency bonds
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,202,377	670,468
Unrealized Gains	1,067	113
Unrealized Losses	(28,430)	(3,872)
Fair Value	1,175,014	666,709
U.S. Treasury securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	89,434	70,106
Unrealized Gains	5	263
Unrealized Losses	(834)	0
Fair Value	88,605	70,369
State and municipal bonds and obligations
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	263,910	260,898
Unrealized Gains	16,460	20,004
Unrealized Losses	(41)	0
Fair Value	280,329	$ 280,902
Small Business Administration pooled securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	31,821
Unrealized Gains	282
Unrealized Losses	0
Fair Value	32,103
Other debt securities
Debt Securities, Available-for-sale [Line Items]
Amortized Cost	1,597
Unrealized Gains	0
Unrealized Losses	0
Fair Value	$ 1,597