Investment Securities - Investment Securities by External Credit Rating (Details) $ in Thousands	Dec. 31, 2021 USD ($)
Debt Securities, Available-for-sale [Line Items]
2021	$ 1,785,251
2020	1,927,257
2019	533,182
2018	129,181
2017	104,463
Prior	176,226
Total	4,655,560
Investment securities available-for-sale
Debt Securities, Available-for-sale [Line Items]
2021	1,736,711
2020	1,607,453
2019	533,182
2018	125,165
2017	101,138
Prior	170,215
Total	4,273,864
Investment securities available-for-sale | U.S. Treasury | Aaa - Aa3
Debt Securities, Available-for-sale [Line Items]
2021	32,727
2020	14,508
2019	0
2018	10,631
2017	0
Prior	0
Total	57,866
Investment securities available-for-sale | Agency | Aaa - Aa3
Debt Securities, Available-for-sale [Line Items]
2021	24,216
2020	296,403
2019	26,017
2018	59,931
2017	0
Prior	12,538
Total	419,105
Investment securities available-for-sale | Agency | Baa1 - Baa3
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	0
2018	5,410
2017	0
Prior	7,620
Total	13,030
Investment securities available-for-sale | Corporate debt | A1 - A3
Debt Securities, Available-for-sale [Line Items]
2021	136,607
2020	67,326
2019	0
2018	0
2017	17,938
Prior	0
Total	221,871
Investment securities available-for-sale | Corporate debt | Baa1 - Baa3
Debt Securities, Available-for-sale [Line Items]
2021	46,492
2020	100,709
2019	71,242
2018	0
2017	0
Prior	13,547
Total	231,990
Investment securities available-for-sale | Municipal bonds | Aaa - Aa3
Debt Securities, Available-for-sale [Line Items]
2021	118,922
2020	563,238
2019	291,483
2018	32,483
2017	50,149
Prior	32,780
Total	1,089,055
Investment securities available-for-sale | Municipal bonds | A1 - A3
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	0
2018	0
2017	0
Prior	858
Total	858
Investment securities available-for-sale | Collateralized mortgage obligations | Aaa - Aa3
Debt Securities, Available-for-sale [Line Items]
2021	268,693
2020	207,155
2019	75,834
2018	16,710
2017	13,274
Prior	94,977
Total	676,643
Investment securities available-for-sale | Mortgage-backed securities | Aaa - Aa3
Debt Securities, Available-for-sale [Line Items]
2021	1,109,054
2020	358,114
2019	68,606
2018	0
2017	19,777
Prior	7,895
Total	1,563,446
Investment securities held-to-maturity
Debt Securities, Available-for-sale [Line Items]
2021	48,540
2020	319,804
2019	0
2018	4,016
2017	3,325
Prior	6,011
Total	381,696
Investment securities held-to-maturity | Municipal bonds | Aaa - Aa3
Debt Securities, Available-for-sale [Line Items]
2021	48,540
2020	319,804
2019	0
2018	0
2017	0
Prior	0
Total	368,344
Investment securities held-to-maturity | Mortgage-backed securities | Aaa - Aa3
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	0
2018	3,425
2017	3,325
Prior	5,093
Total	11,843
Investment securities held-to-maturity | Other | Baa1 - Baa3
Debt Securities, Available-for-sale [Line Items]
2021	0
2020	0
2019	0
2018	591
2017	0
Prior	918
Total	$ 1,509