Investment Securities - HTM debt securities in unrealized loss position (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	$ 798,967	$ 45,502
Unrealized Loss, Less than 12 Months	16,705	490
Fair Value, 12 Months or More	23,791	1,352
Unrealized Loss, 12 Months or More	1,098	10
Fair Value, Total	822,758	46,854
Unrealized Loss, Total	17,803	500
U.S. Government agencies & GSEs
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	64,658	4,677
Unrealized Loss, Less than 12 Months	888	11
Fair Value, 12 Months or More	4,401	0
Unrealized Loss, 12 Months or More	233	0
Fair Value, Total	69,059	4,677
Unrealized Loss, Total	1,121	11
State and political subdivisions
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	131,128	14,870
Unrealized Loss, Less than 12 Months	3,590	242
Fair Value, 12 Months or More	9,006	0
Unrealized Loss, 12 Months or More	490	0
Fair Value, Total	140,134	14,870
Unrealized Loss, Total	4,080	242
Residential MBS, Agency & GSE
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	289,132	999
Unrealized Loss, Less than 12 Months	3,687	1
Fair Value, 12 Months or More	0	0
Unrealized Loss, 12 Months or More	0	0
Fair Value, Total	289,132	999
Unrealized Loss, Total	3,687	1
Commercial MBS, Agency & GSE
Summary of HTM debt securities in an unrealized loss position
Fair Value, Less than 12 Months	314,049	24,956
Unrealized Loss, Less than 12 Months	8,540	236
Fair Value, 12 Months or More	10,384	1,352
Unrealized Loss, 12 Months or More	375	10
Fair Value, Total	324,433	26,308
Unrealized Loss, Total	$ 8,915	$ 246