Investment Securities - Schedule of Amortized Cost and Estimated Fair Value of Investments Available-for-Sale by Contractual Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Amortized Cost
Total investment securities available-for-sale	$ 1,668,316
Estimated Fair Value
Less: allowance for credit losses	(17)	$ (17)
Total investment securities available-for-sale	1,506,388
Amortized Cost
Less: allowance for credit losses	(1,956)	(766)
Total investment securities held-to-maturity	1,015,737	1,093,374
Estimated Fair Value
Total investment securities held-to-maturity	901,582	968,707
Asset-Backed Securities
Amortized Cost
Within one year	141,266
One to five years	491,268
Five to ten years	136,583
Beyond ten years	20,650
Estimated Fair Value
Within one year	137,159
One to five years	454,697
Five to ten years	119,582
Beyond ten years	18,050
Amortized Cost
Within one year	4,307
One to five years	56,444
Five to ten years	121,107
Beyond ten years	75,565
Less: allowance for credit losses	(1,956)
Total investment securities held-to-maturity	1,015,737
Total	2,684,053
Estimated Fair Value
Within one year	4,258
One to five years	54,589
Five to ten years	105,719
Beyond ten years	69,593
Total investment securities held-to-maturity	901,582
Total	2,407,970
Residential mortgage-backed securities
Amortized Cost
Amortized cost, without maturity date	823,992
Total investment securities available-for-sale	823,992	937,557
Estimated Fair Value
Estimated fair value, without maturity date	727,353
Less: allowance for credit losses	0	0
Amortized Cost
Amortized cost, without maturity date	670,043
Estimated Fair Value
Estimated fair value, without maturity date	590,063
Total investment securities held-to-maturity	590,063	652,667
Commercial mortgage-backed securities
Amortized Cost
Amortized cost, without maturity date	54,557
Total investment securities available-for-sale	54,557	56,071
Estimated Fair Value
Estimated fair value, without maturity date	49,564
Less: allowance for credit losses	0	0
Amortized Cost
Amortized cost, without maturity date	90,227
Estimated Fair Value
Estimated fair value, without maturity date	77,360
Total investment securities held-to-maturity	$ 77,360	$ 80,564