Long-Term Debt - Details of Debentures (Details) $ in Thousands	Dec. 31, 2021 USD ($)
PHC Statutory Trust I
Debentures details
Principal Amount	$ 20,619
Interest Rate	3.07%
Amount Included in Tier 1 Capital	$ 20,000
PHC Statutory Trust II
Debentures details
Principal Amount	$ 31,959
Interest Rate	2.07%
Amount Included in Tier 1 Capital	$ 31,000
Capital Bancorp Capital Trust I
Debentures details
Principal Amount	$ 12,372
Interest Rate	1.72%
Amount Included in Tier 1 Capital	$ 12,000
First M&F Statutory Trust I
Debentures details
Principal Amount	$ 30,928
Interest Rate	1.53%
Amount Included in Tier 1 Capital	$ 22,194
Brand Group Holdings Statutory Trust I
Debentures details
Principal Amount	$ 10,310
Interest Rate	2.27%
Amount Included in Tier 1 Capital	$ 9,216
Brand Group Holdings Statutory Trust II
Debentures details
Principal Amount	$ 5,155
Interest Rate	3.20%
Amount Included in Tier 1 Capital	$ 5,051
Brand Group Holdings Statutory Trust III
Debentures details
Principal Amount	$ 5,155
Interest Rate	3.20%
Amount Included in Tier 1 Capital	$ 5,051
Brand Group Holdings Statutory Trust IV
Debentures details
Principal Amount	$ 3,093
Interest Rate	3.95%
Amount Included in Tier 1 Capital	$ 3,270

Amount of the total principal payments made during the annual reporting period.

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))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Weighted average interest rate of long-term debt outstanding calculated at point in time.

+ References

No definition available.

+ Details

Name:	us-gaap_LongtermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of Tier 1 leverage capital as defined by regulatory framework.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117337116&loc=SL5958568-112826

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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