XML 126 R116.htm IDEA: XBRL DOCUMENT v3.21.1

Borrowings - Subordinated Debt (Details)		12 Months Ended
	Aug. 15, 2020 USD ($) issue	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2003 USD ($) trust	Mar. 31, 2021 USD ($)
Debt Instrument [Line Items]
Issuance of subordinated debt, net of issuance costs		$ 98,228,000	$ 0	$ 0
Net proceeds from sale of common stock under employee stock purchase program		978,000	804,000	$ 1,196,000
Borrowings		238,324,000	304,675,000
Subordinated debt
Debt Instrument [Line Items]
Number of separate trusts | trust					2
Borrowings		30,930,000
Subordinated debt | Franklin Financial Network, Inc.
Debt Instrument [Line Items]
Debt instrument, face amount	$ 60,000,000
Number of issues | issue	2
Fair value premium adjustment		369,000
Borrowings		60,369,000
Subordinated debt | Minimum | Franklin Financial Network, Inc.
Debt Instrument [Line Items]
Debt instrument, interest rate, phase two period	6 years
Subordinated debt | Maximum | Franklin Financial Network, Inc.
Debt Instrument [Line Items]
Debt instrument, interest rate, phase two period	10 years
Subordinated debt | Floating Rate Trust Preferred Securities Trust
Debt Instrument [Line Items]
Preferred securities issued to form the trust		$ 30,000,000	$ 30,000,000
Distribution payment period of occurrence of a special event		120 days
Subordinated debt | Floating Rate Trust Preferred Securities Trust I
Debt Instrument [Line Items]
Preferred securities issued to form the trust					$ 9,000,000
Issuance of subordinated debt, net of issuance costs					9,280,000
Net proceeds from sale of common stock under employee stock purchase program					$ 280,000
Debt instrument, interest rate		3.50%	5.19%
Subordinated debt | Floating Rate Trust Preferred Securities Trust I | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on debt variable rate					3.25%
Subordinated debt | Floating Rate Trust Preferred Securities Trust II
Debt Instrument [Line Items]
Preferred securities issued to form the trust					$ 21,000,000
Issuance of subordinated debt, net of issuance costs					21,650,000
Net proceeds from sale of common stock under employee stock purchase program					$ 650,000
Debt instrument, interest rate		3.40%	5.10%
Subordinated debt | Floating Rate Trust Preferred Securities Trust II | London Interbank Offered Rate (LIBOR)
Debt Instrument [Line Items]
Basis spread on debt variable rate					3.15%
Subordinated debt | Fixed To Floating Rate Note
Debt Instrument [Line Items]
Basis spread on debt variable rate		4.39%
Debt instrument, interest rate		4.50%
Debt instrument, face amount		$ 100,000,000
Long-term debt, term		10 years
Debt instrument, interest rate, phase one period		5 years
Unamortized debt issuance costs		$ 1,772,000
Percentage of tier 2 capital treatment lost		20.00%
Period for loss of tier 2 capital treatment		5 years
Subordinated debt | Fixed To Floating Rate Note | Minimum
Debt Instrument [Line Items]
Debt instrument, interest rate, phase two period		6 years
Subordinated debt | Fixed To Floating Rate Note | Maximum
Debt Instrument [Line Items]
Debt instrument, interest rate, phase two period		10 years
Subordinated debt | March 2026 Subordinated Notes | Franklin Financial Network, Inc.
Debt Instrument [Line Items]
Preferred securities issued to form the trust	$ 40,000,000
Debt instrument, interest rate	6.875%
Subordinated debt | March 2026 Subordinated Notes | Franklin Financial Network, Inc. | Subsequent Event | Forecast
Debt Instrument [Line Items]
Debt redemption amount						$ 40,000,000.0
Subordinated debt | March 2026 Subordinated Notes | London Interbank Offered Rate (LIBOR) | Franklin Financial Network, Inc.
Debt Instrument [Line Items]
Basis spread on debt variable rate	5.636%
Subordinated debt | July 2026 Subordinated Notes | Franklin Financial Network, Inc.
Debt Instrument [Line Items]
Preferred securities issued to form the trust	$ 20,000
Debt instrument, interest rate	7.00%
Subordinated debt | July 2026 Subordinated Notes | London Interbank Offered Rate (LIBOR) | Franklin Financial Network, Inc.
Debt Instrument [Line Items]
Basis spread on debt variable rate	6.04%

X

- Definition

Debt, Distribution Payment Period Of Occurrence Of A Special Event

+ References

No definition available.

+ Details

Name:	fbk_DebtDistributionPaymentPeriodOfOccurrenceOfASpecialEvent
Namespace Prefix:	fbk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Debt Instrument, Interest Rate, Phase One Period

+ References

No definition available.

+ Details

Name:	fbk_DebtInstrumentInterestRatePhaseOnePeriod
Namespace Prefix:	fbk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Debt Instrument, Interest Rate, Phase Two Period

+ References

No definition available.

+ Details

Name:	fbk_DebtInstrumentInterestRatePhaseTwoPeriod
Namespace Prefix:	fbk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Debt, Number of Issues

+ References

No definition available.

+ Details

Name:	fbk_DebtNumberOfIssues
Namespace Prefix:	fbk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Debt, Percentage of Tier 2 Capital Treatment Lost

+ References

No definition available.

+ Details

Name:	fbk_DebtPercentageOfTier2CapitalTreatmentLost
Namespace Prefix:	fbk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Debt, Period For Loss of Tier 2 Capital Treatment

+ References

No definition available.

+ Details

Name:	fbk_DebtPeriodForLossOfTier2CapitalTreatment
Namespace Prefix:	fbk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of trusts.

+ References

No definition available.

+ Details

Name:	fbk_NumberOfTrusts
Namespace Prefix:	fbk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Face (par) amount of the original debt instrument that was repurchased.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentRepurchasedFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount, after accumulated amortization, of debt discount (premium).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28567-108399

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28541-108399

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

+ Details

Name:	us-gaap_DebtInstrumentUnamortizedDiscountPremiumNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount, before accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28555-108399

+ Details

Name:	us-gaap_DeferredFinanceCostsGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Period between issuance and maturity of long-term debt, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_LongTermDebtTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

X

- Definition

The cash inflow from the additional capital contribution to the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfCommonStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The cash inflow from issuance of preferred stocks by a business trust or other special purpose entity, mainly established by a bank holding entity, to third party investors. The trust's assets are deeply subordinated debentures of the bank holding entity. Most trust preferred securities are subject to a mandatory redemption upon the repayment of the debentures.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfTrustPreferredSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SubordinatedDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_BusinessAcquisitionAxis=fbk_FranklinFinancialNetworkInc.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DebtInstrumentAxis=fbk_FloatingRateTrustPreferredSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DebtInstrumentAxis=fbk_FloatingRateTrustPreferredSecuritiesTrustIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DebtInstrumentAxis=fbk_FloatingRateTrustPreferredSecuritiesTrustIIMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DebtInstrumentAxis=fbk_FixedToFloatingRateNoteMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DebtInstrumentAxis=fbk_March2026SubordinatedNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DebtInstrumentAxis=fbk_July2026SubordinatedNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: