Long-Term Debt (Details 1) $ in Thousands	12 Months Ended
Dec. 31, 2015 USD ($)
PHC Statutory Trust I
Debentures details
Principal Amount	$ 20,619
Interest Rate (percent)	3090.00%
Year of Maturity	2033
Amount Included in Tier 1 Capital	$ 20,000
PHC Statutory Trust II
Debentures details
Principal Amount	$ 31,959
Interest Rate (percent)	2.38%
Year of Maturity	2035
Amount Included in Tier 1 Capital	$ 31,000
Heritage Financial Statutory Trust I
Debentures details
Principal Amount	$ 10,310
Interest Rate (percent)	10.20%
Year of Maturity	2031
Amount Included in Tier 1 Capital	$ 10,000
Capital Bancorp Capital Trust I
Debentures details
Principal Amount	$ 12,372
Interest Rate (percent)	2.10%
Year of Maturity	2035
Amount Included in Tier 1 Capital	$ 12,000
First M&F Statutory Trust I
Debentures details
Principal Amount	$ 30,928
Interest Rate (percent)	1.84%
Year of Maturity	2036
Amount Included in Tier 1 Capital	$ 18,907

Debenture year of maturity.

No definition available.

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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 22
-Article 5

+ Details

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

- References

No definition available.

+ Details

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Balance Type:	na
Period Type:	duration

- Definition

Weighted average interest rate of long-term debt outstanding.

+ References

No definition available.

+ Details

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Data Type:	num:percentItemType
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- Definition

Tier 1 Leverage Capital as defined in the regulations. Also called Core Capital.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=SL5958568-112826

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 505
-Section 50
-Paragraph 1H
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=35709795&loc=d3e65071-112826

+ Details

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

- Details

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Namespace Prefix:
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Balance Type:
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- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

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

- Details

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

- Details

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Namespace Prefix:
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Period Type: