Securities - Summary Of Government-Sponsored Residential Mortgage-Backed Securities With Gross Unrealized Losses (Detail) $ in Thousands	Sep. 30, 2022 USD ($) holding	Dec. 31, 2021 USD ($) holding
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	850	470
Gross Unrealized Losses
Less than 12 Months	$ 485,712	$ 85,764
12 Months or Longer	699,014	26,683
Total	1,184,726	112,447
Fair Value
Less than 12 Months	3,047,852	5,993,147
12 Months or Longer	3,794,283	810,035
Total	$ 6,842,135	$ 6,803,182
Government-sponsored residential mortgage-backed securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	322	264
Gross Unrealized Losses
Less than 12 Months	$ 278,329	$ 70,502
12 Months or Longer	507,849	0
Total	786,178	70,502
Fair Value
Less than 12 Months	1,541,349	4,615,457
12 Months or Longer	2,667,740	0
Total	$ 4,209,089	$ 4,615,457
Government-sponsored commercial mortgage-backed securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	200	165
Gross Unrealized Losses
Less than 12 Months	$ 145,210	$ 12,218
12 Months or Longer	60,609	422
Total	205,819	12,640
Fair Value
Less than 12 Months	1,050,544	1,102,444
12 Months or Longer	346,683	15,682
Total	$ 1,397,227	$ 1,118,126
U.S. Agency bonds
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	37	27
Gross Unrealized Losses
Less than 12 Months	$ 29,820	$ 2,169
12 Months or Longer	129,148	26,261
Total	158,968	28,430
Fair Value
Less than 12 Months	210,070	191,222
12 Months or Longer	731,527	794,353
Total	$ 941,597	$ 985,575
U.S. Treasury securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	5	3
Gross Unrealized Losses
Less than 12 Months	$ 5,399	$ 834
12 Months or Longer	1,408	0
Total	6,807	834
Fair Value
Less than 12 Months	44,127	78,588
12 Months or Longer	48,333	0
Total	$ 92,460	$ 78,588
State and municipal bonds and obligations
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	283	11
Gross Unrealized Losses
Less than 12 Months	$ 26,933	$ 41
12 Months or Longer	0	0
Total	26,933	41
Fair Value
Less than 12 Months	200,184	5,436
12 Months or Longer	0	0
Total	$ 200,184	$ 5,436
Other debt securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	3
Gross Unrealized Losses
Less than 12 Months	$ 21
12 Months or Longer	0
Total	21
Fair Value
Less than 12 Months	1,578
12 Months or Longer	0
Total	$ 1,578