Securities Available for Sale - Maturities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Amortized Cost
Amortized cost, due within 1 year	$ 230
Amortized cost, due after 1 year through 5 years	451,670
Amortized cost, due after 5 years through 10 years	42,249
Amortized cost, due after 10 years	378,192
Amortized Cost	872,341	$ 399,668
Fair Value
Fair value, due within 1 year	230
Fair value, due after 1 year through 5 years	453,798
Fair value, due after 5 years through 10 years	39,159
Fair value, due after 10 years	302,482
Fair Value	$ 795,669	345,702
Weighted-average yield, due within 1 year	46.15%
Weighted-average yield, due after 1 year through 5 years	3.17%
Weighted-average yield, due after 5 years through 10 years	4.27%
Weighted-average yield, due after 10 years	2.80%
Weighted-average yield	3.07%
Senior asset-backed securities related to Structured Program transactions
Amortized Cost
Amortized cost, due within 1 year	$ 230
Amortized cost, due after 1 year through 5 years	413,620
Amortized Cost	413,850
Fair Value
Fair value, due within 1 year	230
Fair value, due after 1 year through 5 years	412,167
Fair Value	412,397
Other asset-backed securities related to Structured Program transactions
Amortized Cost
Amortized cost, due after 1 year through 5 years	26,831
Amortized Cost	26,831
Fair Value
Fair value, due after 1 year through 5 years	31,062
Fair Value	31,062
U.S. agency securities
Amortized Cost
Amortized cost, due after 1 year through 5 years	9,000
Amortized cost, due after 5 years through 10 years	18,848
Amortized cost, due after 10 years	65,603
Amortized Cost	93,451	90,447
Fair Value
Fair value, due after 1 year through 5 years	8,567
Fair value, due after 5 years through 10 years	16,768
Fair value, due after 10 years	49,744
Fair Value	75,079	74,394
Mortgage-backed securities
Amortized Cost
Amortized cost, due after 1 year through 5 years	1,774
Amortized cost, due after 5 years through 10 years	2,036
Amortized cost, due after 10 years	39,352
Amortized Cost	43,162	26,988
Fair Value
Fair value, due after 1 year through 5 years	1,556
Fair value, due after 5 years through 10 years	1,634
Fair value, due after 10 years	32,959
Fair Value	36,149	22,518
Other asset-backed securities
Amortized Cost
Amortized cost, due after 1 year through 5 years	441
Amortized cost, due after 5 years through 10 years	15,567
Amortized cost, due after 10 years	12,209
Amortized Cost	28,217	14,959
Fair Value
Fair value, due after 1 year through 5 years	443
Fair value, due after 5 years through 10 years	15,545
Fair value, due after 10 years	11,476
Fair Value	27,464	14,203
U.S. agency residential mortgage-backed securities
Amortized Cost
Amortized cost, due after 1 year through 5 years	4
Amortized cost, due after 5 years through 10 years	5,177
Amortized cost, due after 10 years	258,387
Fair Value
Fair value, due after 1 year through 5 years	3
Fair value, due after 5 years through 10 years	4,696
Fair value, due after 10 years	206,538
Fair Value	211,237	214,427
Municipal securities
Amortized Cost
Amortized cost, due after 5 years through 10 years	621
Amortized cost, due after 10 years	2,641
Amortized Cost	3,262	3,277
Fair Value
Fair value, due after 5 years through 10 years	516
Fair value, due after 10 years	1,765
Fair Value	$ 2,281	$ 2,443