Commitments and Contingencies - Additional Information (Detail) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Commitments and Contingencies Disclosure [Abstract]
Lease agreement commencement date	2014-04-01
Lease agreement maturity date	Mar. 31, 2019
Approximate monthly base rent	$ 9,000us-gaap_PaymentsForRent
Annual increase in base rent percentage	3.00%
Operating lease expenses	$ 107,500us-gaap_LeaseAndRentalExpense	$ 62,900us-gaap_LeaseAndRentalExpense

Date which lease or group of leases is set to commence, in CCYY-MM-DD format.

No definition available.

Name:	rxii_LeaseCommencementDate
Namespace Prefix:	rxii_
Data Type:	us-types:dateStringItemType
Balance Type:	na
Period Type:	duration

- Definition

Expected percentage increase in annual base rate on the lessee's operating lease.

+ References

No definition available.

+ Details

Name:	rxii_PercentageOfIncreaseInAnnualBaseRent
Namespace Prefix:	rxii_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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

- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

+ Details

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

- Definition

Date which lease or group of leases is set to expire, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_LeaseExpirationDate1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Cash payments to lessor's for use of assets under operating leases.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 25

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3536-108585

+ Details

Name:	us-gaap_PaymentsForRent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration