Related Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
FOXKISER,LLP [Member] \| Service Agreements [Member] \| Research and Development Costs [Member]
Related Party Transaction [Line Items]
Related party transaction expense	$ 0.4	$ 0.2
Special Scientific Advisor [Member]
Related Party Transaction [Line Items]
Related party transaction expenses from transactions with related party advisory fees	$ 0.1	$ 0.1
Shares, Granted	211,600

Related party transaction expenses from transactions with related party advisory fees.

No definition available.

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Namespace Prefix:	rgnx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

+ Details

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

- 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

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Gross number of share options (or share units) granted during the period.

+ References

No definition available.

+ Details

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Period Type:	duration

- Details

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- Details

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- Details

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Namespace Prefix:
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- Details

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