Subordinated Debentures - Schedule of Subordinated Debentures (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Mar. 23, 2007	Jun. 15, 2005	Sep. 20, 2004	Mar. 26, 2003
Subordinated Borrowing [Line Items]
Total subordinated debentures	$ 103,943	$ 103,799
Subordinated Note [Member]
Subordinated Borrowing [Line Items]
Total subordinated debentures	73,594	73,450
First Citizens Statutory Trust II [Member]
Subordinated Borrowing [Line Items]
Total subordinated debentures	7,732	7,732				$ 7,700
First Citizens Statutory Trust III [Member]
Subordinated Borrowing [Line Items]
Total subordinated debentures	12,887	12,887			$ 12,900
First Citizens Statutory Trust IV [Member]
Subordinated Borrowing [Line Items]
Total subordinated debentures	5,155	5,155	$ 5,200
Futura TPF Trust I [Member]
Subordinated Borrowing [Line Items]
Total subordinated debentures	2,578	2,578		$ 2,600
Futura TPF Trust II [Member]
Subordinated Borrowing [Line Items]
Total subordinated debentures	$ 1,997	$ 1,997		$ 2,100