Securities - Summary Of Government-Sponsored Residential Mortgage-Backed Securities With Gross Unrealized Losses (Detail) $ in Thousands	Jun. 30, 2023 USD ($) holding	Dec. 31, 2022 USD ($) holding
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	775	802
Gross Unrealized Losses
Less than 12 Months	$ 8,294	$ 98,038
12 Months or Longer	829,717	1,036,628
Total	838,011	1,134,666
Fair Value
Less than 12 Months	173,951	968,376
12 Months or Longer	4,338,931	5,719,149
Total	$ 4,512,882	$ 6,687,525
Government-sponsored residential mortgage-backed securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	324	322
Gross Unrealized Losses
Less than 12 Months	$ 5,254	$ 42,196
12 Months or Longer	574,409	701,659
Total	579,663	743,855
Fair Value
Less than 12 Months	79,823	435,690
12 Months or Longer	2,811,241	3,676,218
Total	$ 2,891,064	$ 4,111,908
Government-sponsored commercial mortgage-backed securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	188	199
Gross Unrealized Losses
Less than 12 Months	$ 0	$ 38,944
12 Months or Longer	214,027	182,221
Total	214,027	221,165
Fair Value
Less than 12 Months	0	300,476
12 Months or Longer	1,140,160	1,048,478
Total	$ 1,140,160	$ 1,348,954
U.S. Agency bonds
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	23	37
Gross Unrealized Losses
Less than 12 Months	$ 0	$ 645
12 Months or Longer	25,774	147,764
Total	25,774	148,409
Fair Value
Less than 12 Months	0	4,145
12 Months or Longer	210,070	948,337
Total	$ 210,070	$ 952,482
U.S. Treasury securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	6	5
Gross Unrealized Losses
Less than 12 Months	$ 519	$ 1,311
12 Months or Longer	5,836	4,956
Total	6,355	6,267
Fair Value
Less than 12 Months	19,364	48,451
12 Months or Longer	73,718	44,606
Total	$ 93,082	$ 93,057
State and municipal bonds and obligations
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding	234	237
Gross Unrealized Losses
Less than 12 Months	$ 2,521	$ 14,942
12 Months or Longer	9,671	14
Total	12,192	14,956
Fair Value
Less than 12 Months	74,764	179,614
12 Months or Longer	103,742	225
Total	$ 178,506	$ 179,839
Other debt securities
Debt Securities, Held-to-maturity, Allowance for Credit Loss [Line Items]
Number of holdings | holding		2
Gross Unrealized Losses
Less than 12 Months		$ 0
12 Months or Longer		14
Total		14
Fair Value
Less than 12 Months		0
12 Months or Longer		1,285
Total		$ 1,285