Lessee, Number of Operating Leases, Noncurrent

No definition available.

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

- Definition

Lessee, Operating Lease, Number Of Options To Renew

+ References

No definition available.

+ Details

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

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

- Definition

Term of lessee's operating lease renewal, 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 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

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

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

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

- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717

+ Details

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

- Details

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

- Details

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

Leases (Details) $ in Thousands	3 Months Ended	9 Months Ended
Leases (Details) $ in Thousands	Sep. 30, 2018 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 lease_renew_option lease
Lessee, Lease, Description [Line Items]
Lessee, number of operating leases, noncurrent \| lease			42
Lessee, operating lease, number of options to renew \| lease_renew_option			1
Operating lease rent expense \| $	$ 1,295	$ 3,786
Minimum
Lessee, Lease, Description [Line Items]
Lessee, operating lease, term of contract			1 year
Lessee, operating lease, renewal term			20 years
Maximum
Lessee, Lease, Description [Line Items]
Lessee, operating lease, term of contract			37 years