Investment Securities - Amortized Cost of Investment Securities Held to Maturity (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 2,333,924	$ 2,180,047
Aaa
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	162,632
Aa1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	163,091
Aa2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	185,950
Aa3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	134,000
A1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	132,754
A2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	10,165
A3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	10,112
Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,535,220
State and municipal
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,117,526	$ 1,057,301
State and municipal | Aaa
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	102,051
State and municipal | Aa1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	163,091
State and municipal | Aa2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	185,950
State and municipal | Aa3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	134,000
State and municipal | A1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	132,754
State and municipal | A2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	10,165
State and municipal | A3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	10,112
State and municipal | Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	379,403
Other
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	1,216,398
Other | Aaa
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	60,581
Other | Aa1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | Aa2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | Aa3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | A1
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | A2
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | A3
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	0
Other | Non-rated
Schedule of Held-to-maturity Securities [Line Items]
Amortized Cost	$ 1,155,817