Accounting for Certain Loans Acquired in a Transfer - Summary of accretable yield or income expected to be collected (Details 1) (Dupont State Bank, Loans Receivable, USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Dupont State Bank \| Loans Receivable
Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]
Balance at January 1	$ 1,345	$ 673
Additions
Accretion	(380)	(510)
Reclassification from non-accretable difference	297	1,182
Disposals
Balance at December 31	$ 1,262	$ 1,345

Accounting for Certain Loans Acquired in a Transfer - Summary of accretable yield or income expected to be collected (Details 1) (Dupont State Bank, Loans Receivable, USD $)
In Thousands, unless otherwise specified

12 Months Ended

Dec. 31, 2014

Dec. 31, 2013

Dupont State Bank | Loans Receivable

Certain Loans Acquired in Transfer Accounted for as Debt Securities, Accretable Yield Movement Schedule [Roll Forward]

Balance at January 1

$ 1,345us-gaap_CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYield
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember
/ us-gaap_BusinessAcquisitionAxis
= rivr_DupontStateBankMember

$ 673us-gaap_CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYield
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember
/ us-gaap_BusinessAcquisitionAxis
= rivr_DupontStateBankMember

Additions

Accretion

(380)us-gaap_CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYieldAccretion
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember
/ us-gaap_BusinessAcquisitionAxis
= rivr_DupontStateBankMember

(510)us-gaap_CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYieldAccretion
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember
/ us-gaap_BusinessAcquisitionAxis
= rivr_DupontStateBankMember

Reclassification from non-accretable difference

297us-gaap_CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYieldReclassificationsFromNonaccretableDifference
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember
/ us-gaap_BusinessAcquisitionAxis
= rivr_DupontStateBankMember

1,182us-gaap_CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYieldReclassificationsFromNonaccretableDifference
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember
/ us-gaap_BusinessAcquisitionAxis
= rivr_DupontStateBankMember

Disposals

Balance at December 31

$ 1,262us-gaap_CertainLoansAcquiredInTransferAccountedForAsDebtSecuritiesAccretableYield
/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis
= us-gaap_LoansReceivableMember
/ us-gaap_BusinessAcquisitionAxis
= rivr_DupontStateBankMember

- Definition

The aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan for loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 15

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=27045933&loc=d3e13503-111538

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(2)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

+ Details

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- Definition

Current period recognition due to accretion of the excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan for loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

+ Details

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- Definition

Increases in the aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan due to the acquisition of similar loans accounted for as debt securities during the period. This relates to loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

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- Definition

Sale or transfer of a loan during the period resulting in a reduction in the excess of a loan's cash flows expected to be collected over the investor's initial investment. This relates to loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

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- Details

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- Definition

Change in the estimate of cash flows expected to be collected, after acquisition of a loan, which results in an increase in accretable yield (for example, if actual cash flows are significantly greater than previously expected). This relates to loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that was acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable.

+ References

+ Details

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