Summary of Significant Accounting Policies - Additional Information (Detail)	3 Months Ended
Mar. 31, 2017
Accounting Policies [Abstract]
Estimated forfeiture rate on share-based awards granted	0.00%

Forfeiture rate used to calculate stock-based compensation expense.

No definition available.

Name:	rgnx_ForfeitureRateUsedToCalculateStockBasedCompensationExpense
Namespace Prefix:	rgnx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration