Income Taxes - Additional Information (Detail)	1 Months Ended
Mar. 31, 2020
Income Tax Disclosure [Abstract]
Elimination of limitation in net operating losses deductions as percentage of current year taxable income, percentage	80.00%

CARES Act of 2020, elimination of net operating loss deductions as percentage of taxable income.

No definition available.

Name:	rgnx_CARESActOf2020EliminationOfNetOperatingLossDeductionsAsPercentageOfTaxableIncome
Namespace Prefix:	rgnx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration