Subordinated Debentures - Schedule of Subordinated Debentures (Parenthetical) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Subordinated Note [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	3.25%	3.25%
Subordinated Note [Member] | December 31, 2031 [Member]
Subordinated Borrowing [Line Items]
Maturities of subordinated debt	$ 75,000
Subordinated Note [Member] | SOFR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	2.19%
First Citizens Statutory Trust II [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	8.81%	6.79%
First Citizens Statutory Trust II [Member] | March 26, 2033 [Member]
Subordinated Borrowing [Line Items]
Maturities of subordinated debt	$ 7,732
First Citizens Statutory Trust II [Member] | SOFR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	3.15%
First Citizens Statutory Trust III [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	7.91%	5.78%
First Citizens Statutory Trust III [Member] | September 20, 2034 [Member]
Subordinated Borrowing [Line Items]
Maturities of subordinated debt	$ 12,887
First Citizens Statutory Trust III [Member] | SOFR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	2.25%
First Citizens Statutory Trust IV [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	7.27%	4.89%
First Citizens Statutory Trust IV [Member] | March 23, 2037 [Member]
Subordinated Borrowing [Line Items]
Maturities of subordinated debt	$ 5,155
First Citizens Statutory Trust IV [Member] | SOFR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	1.60%
Futura TPF Trust II [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	7.33%	4.95%
Futura TPF Trust II [Member] | June 15, 2035 [Member]
Subordinated Borrowing [Line Items]
Maturities of subordinated debt	$ 2,070
Futura TPF Trust II [Member] | 3-Month LIBOR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	1.66%
Futura TPF Trust I [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	7.33%	4.95%
Futura TPF Trust I [Member] | June 15, 2035 [Member]
Subordinated Borrowing [Line Items]
Maturities of subordinated debt	$ 2,578
Futura TPF Trust I [Member] | SOFR [Member]
Subordinated Borrowing [Line Items]
Basis spread on variable rate	1.66%