Loans and Leases Held for Investment at Amortized Cost, Net of Allowance for Loan and Lease Losses - Credit Quality Indicators (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Term Loans and Leases by Origination Year
Total	$ 5,237,277	$ 5,033,154
Loans and leases held for investment at amortized cost
Term Loans and Leases by Origination Year
Portfolio layer method basis adjustment - increase (decrease)	(3,020)
Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method
Term Loans and Leases by Origination Year
Year 1	1,630,506	3,064,021
Year 2	2,166,634	1,102,517
Year 3	657,314	31,465
Year 4	30,204	24,226
Year 5	22,884	4,546
Prior	30,841	33,833
Total	4,538,383	4,260,608
Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Unsecured personal
Term Loans and Leases by Origination Year
Year 1	1,516,076	2,861,207
Year 2	2,006,552	1,005,166
Year 3	575,140	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	4,097,768	3,866,373
Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Residential mortgages
Term Loans and Leases by Origination Year
Year 1	0	49,721
Year 2	48,934	58,353
Year 3	56,128	31,465
Year 4	30,204	21,683
Year 5	20,403	4,546
Prior	30,841	33,833
Total	186,510	199,601
Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Secured consumer
Term Loans and Leases by Origination Year
Year 1	114,430	153,093
Year 2	111,148	38,998
Year 3	26,046	0
Year 4	0	2,543
Year 5	2,481	0
Prior	0	0
Total	254,105	194,634
Commercial Portfolio Segment
Term Loans and Leases by Origination Year
Year 1	78,296	220,905
Year 2	226,531	202,382
Year 3	124,069	111,040
Year 4	71,462	91,253
Year 5	77,064	57,687
Prior	124,492	89,279
Total	701,914	772,546
Commercial Portfolio Segment | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	169,833	189,756
Commercial Portfolio Segment | Equipment finance
Term Loans and Leases by Origination Year
Year 1	3,266	59,227
Year 2	51,497	40,312
Year 3	31,452	25,873
Year 4	15,709	19,544
Year 5	11,835	11,919
Prior	11,530	3,444
Total	125,289	160,319
Commercial Portfolio Segment | Equipment finance | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	0	0
Commercial Portfolio Segment | Equipment finance | Pass
Term Loans and Leases by Origination Year
Year 1	3,266	59,227
Year 2	36,438	38,218
Year 3	29,017	25,014
Year 4	9,088	15,785
Year 5	8,963	11,880
Prior	8,797	3,444
Total	95,569	153,568
Commercial Portfolio Segment | Equipment finance | Pass | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	0	0
Commercial Portfolio Segment | Equipment finance | Special mention
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	15,059	2,094
Year 3	2,435	0
Year 4	6,085	3,759
Year 5	2,872	0
Prior	0	0
Total	26,451	5,853
Commercial Portfolio Segment | Equipment finance | Special mention | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	0	0
Commercial Portfolio Segment | Equipment finance | Substandard
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	0	859
Year 4	536	0
Year 5	0	39
Prior	2,733	0
Total	3,269	898
Commercial Portfolio Segment | Equipment finance | Substandard | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	0	0
Commercial Portfolio Segment | Equipment finance | Doubtful
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	0	0
Commercial Portfolio Segment | Equipment finance | Doubtful | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	0	0
Commercial Portfolio Segment | Equipment finance | Loss
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	0	0
Commercial Portfolio Segment | Equipment finance | Loss | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	0	0
Commercial Portfolio Segment | Commercial real estate
Term Loans and Leases by Origination Year
Year 1	39,237	100,602
Year 2	98,286	53,445
Year 3	43,331	55,912
Year 4	43,382	53,737
Year 5	52,287	39,633
Prior	96,723	70,172
Total	373,246	373,501
Commercial Portfolio Segment | Commercial real estate | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	43,667	40,693
Commercial Portfolio Segment | Commercial real estate | Pass
Term Loans and Leases by Origination Year
Year 1	39,237	100,602
Year 2	94,645	53,445
Year 3	35,078	47,497
Year 4	43,382	52,834
Year 5	52,066	35,992
Prior	76,254	60,976
Total	340,662	351,346
Commercial Portfolio Segment | Commercial real estate | Pass | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	33,681	40,693
Commercial Portfolio Segment | Commercial real estate | Special mention
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	0	8,415
Year 4	0	260
Year 5	0	1,237
Prior	9,362	405
Total	9,362	10,317
Commercial Portfolio Segment | Commercial real estate | Special mention | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	0	0
Commercial Portfolio Segment | Commercial real estate | Substandard
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	3,641	0
Year 3	6,738	0
Year 4	0	643
Year 5	221	2,404
Prior	10,571	8,215
Total	21,171	11,262
Commercial Portfolio Segment | Commercial real estate | Substandard | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	8,515	0
Commercial Portfolio Segment | Commercial real estate | Doubtful
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	0	0
Commercial Portfolio Segment | Commercial real estate | Doubtful | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	0	0
Commercial Portfolio Segment | Commercial real estate | Loss
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	1,515	0
Year 4	0	0
Year 5	0	0
Prior	536	576
Total	2,051	576
Commercial Portfolio Segment | Commercial real estate | Loss | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	1,471	0
Commercial Portfolio Segment | Commercial and industrial
Term Loans and Leases by Origination Year
Year 1	35,793	61,076
Year 2	76,748	108,625
Year 3	49,286	29,255
Year 4	12,371	17,972
Year 5	12,942	6,135
Prior	16,239	15,663
Total	203,379	238,726
Commercial Portfolio Segment | Commercial and industrial | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	126,166	149,063
Commercial Portfolio Segment | Commercial and industrial | Pass
Term Loans and Leases by Origination Year
Year 1	35,793	61,076
Year 2	64,912	99,264
Year 3	42,901	24,726
Year 4	10,287	13,866
Year 5	9,136	5,174
Prior	11,054	10,831
Total	174,083	214,937
Commercial Portfolio Segment | Commercial and industrial | Pass | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	107,266	141,858
Commercial Portfolio Segment | Commercial and industrial | Special mention
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	10,734	0
Year 3	1,252	0
Year 4	1,297	483
Year 5	115	163
Prior	385	455
Total	13,783	1,101
Commercial Portfolio Segment | Commercial and industrial | Special mention | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	9,469	44
Commercial Portfolio Segment | Commercial and industrial | Substandard
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	1,102	9,361
Year 3	5,133	4,529
Year 4	787	3,623
Year 5	3,691	797
Prior	3,253	2,820
Total	13,966	21,130
Commercial Portfolio Segment | Commercial and industrial | Substandard | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	7,986	5,716
Commercial Portfolio Segment | Commercial and industrial | Doubtful
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	0	0
Prior	286	286
Total	286	286
Commercial Portfolio Segment | Commercial and industrial | Doubtful | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	216	216
Commercial Portfolio Segment | Commercial and industrial | Loss
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	0	1
Prior	1,261	1,271
Total	1,261	1,272
Commercial Portfolio Segment | Commercial and industrial | Loss | Loans guaranteed by the Small Business Association
Term Loans and Leases by Origination Year
Total	1,229	1,229
Current | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Unsecured personal
Term Loans and Leases by Origination Year
Year 1	1,500,780	2,835,460
Year 2	1,954,955	977,224
Year 3	552,491	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	4,008,226	3,812,684
Current | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Residential mortgages
Term Loans and Leases by Origination Year
Year 1	0	49,721
Year 2	48,934	58,353
Year 3	56,128	31,465
Year 4	30,204	21,683
Year 5	20,403	4,546
Prior	30,678	33,248
Total	186,347	199,016
Current | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Secured consumer
Term Loans and Leases by Origination Year
Year 1	114,186	151,725
Year 2	109,327	38,076
Year 3	25,434	0
Year 4	0	2,543
Year 5	2,481	0
Prior	0	0
Total	251,428	192,344
Past due | Commercial Portfolio Segment
Term Loans and Leases by Origination Year
Total	12,753	5,776
Past due | Commercial Portfolio Segment | Equipment finance
Term Loans and Leases by Origination Year
Total	3,150	4,031
Past due | Commercial Portfolio Segment | Commercial real estate
Term Loans and Leases by Origination Year
Total	6,545	102
Past due | Commercial Portfolio Segment | Commercial and industrial
Term Loans and Leases by Origination Year
Total	3,058	1,643
30-59 days past due | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Unsecured personal
Term Loans and Leases by Origination Year
Year 1	6,728	11,149
Year 2	18,780	9,867
Year 3	7,968	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	33,476	21,016
30-59 days past due | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Residential mortgages
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	0	0
30-59 days past due | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Secured consumer
Term Loans and Leases by Origination Year
Year 1	199	1,017
Year 2	1,188	703
Year 3	291	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	1,678	1,720
30-59 days past due | Commercial Portfolio Segment
Term Loans and Leases by Origination Year
Total	6,007	3,172
30-59 days past due | Commercial Portfolio Segment | Equipment finance
Term Loans and Leases by Origination Year
Total	0	3,172
30-59 days past due | Commercial Portfolio Segment | Commercial real estate
Term Loans and Leases by Origination Year
Total	4,493	0
30-59 days past due | Commercial Portfolio Segment | Commercial and industrial
Term Loans and Leases by Origination Year
Total	1,514	0
60-89 days past due | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Unsecured personal
Term Loans and Leases by Origination Year
Year 1	4,159	7,785
Year 2	15,830	8,633
Year 3	6,679	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	26,668	16,418
60-89 days past due | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Residential mortgages
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	0	0
Prior	0	254
Total	0	254
60-89 days past due | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Secured consumer
Term Loans and Leases by Origination Year
Year 1	45	235
Year 2	484	147
Year 3	261	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	790	382
60-89 days past due | Commercial Portfolio Segment
Term Loans and Leases by Origination Year
Total	3,613	102
60-89 days past due | Commercial Portfolio Segment | Equipment finance
Term Loans and Leases by Origination Year
Total	3,150	0
60-89 days past due | Commercial Portfolio Segment | Commercial real estate
Term Loans and Leases by Origination Year
Total	434	102
60-89 days past due | Commercial Portfolio Segment | Commercial and industrial
Term Loans and Leases by Origination Year
Total	29	0
90 or more days past due | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Unsecured personal
Term Loans and Leases by Origination Year
Year 1	4,409	6,813
Year 2	16,987	9,442
Year 3	8,002	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	29,398	16,255
90 or more days past due | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Residential mortgages
Term Loans and Leases by Origination Year
Year 1	0	0
Year 2	0	0
Year 3	0	0
Year 4	0	0
Year 5	0	0
Prior	163	331
Total	163	331
90 or more days past due | Consumer Portfolio Segment, Excluding Cumulative Basis Adjustment for Portfolio Layer Method | Secured consumer
Term Loans and Leases by Origination Year
Year 1	0	116
Year 2	149	72
Year 3	60	0
Year 4	0	0
Year 5	0	0
Prior	0	0
Total	209	188
90 or more days past due | Commercial Portfolio Segment
Term Loans and Leases by Origination Year
Total	3,133	2,502
90 or more days past due | Commercial Portfolio Segment | Equipment finance
Term Loans and Leases by Origination Year
Total	0	859
90 or more days past due | Commercial Portfolio Segment | Commercial real estate
Term Loans and Leases by Origination Year
Total	1,618	0
90 or more days past due | Commercial Portfolio Segment | Commercial and industrial
Term Loans and Leases by Origination Year
Total	$ 1,515	$ 1,643