Related Party Transactions - Narrative (Details) $ in Thousands	3 Months Ended
Mar. 31, 2025 USD ($) boardSeat	Mar. 31, 2024 USD ($)	Dec. 31, 2024 USD ($)
Related Party Transaction [Line Items]
Deposits from related parties	$ 262,237		$ 282,963
Other income	$ 1,348	$ 1,710
Number of board seats, privately held entity \| boardSeat	2
Amortized cost	$ 1,708,893		1,679,397
Manufactured loan housing securities
Related Party Transaction [Line Items]
Mater loan purchase agreement, maximum capacity	$ 250,000
Master loan purchase agreement, term	5 years
Loans purchased	$ 9,494	9,225
Amortized cost	95,093		86,890
Directors
Related Party Transaction [Line Items]
Operating lease expense	102	90
Directors \| FBK Aviation, LLC \| Aviation Time Sharing Agreements
Related Party Transaction [Line Items]
Other income	19	$ 24
Unfunded Loan Commitment \| Certain Executive Officers, Certain Management and Directors and Their Associates
Related Party Transaction [Line Items]
Unfunded commitments	$ 27,282		$ 14,510

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Financing Receivable, Loan Purchase Agreement, Term

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Number of Board Seats, Privately Held Entity

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Amortized cost excluding accrued interest, before allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of operating lease expense. Excludes sublease income.

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Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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