Commission Fee Rate

No definition available.

Name:	rgls_CommissionFeeRate
Namespace Prefix:	rgls_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Sale of Stock, Value of Shares Available

+ References

No definition available.

+ Details

Name:	rgls_SaleOfStockValueOfSharesAvailable
Namespace Prefix:	rgls_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

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

- Definition

The amount of cash paid for commissions during the current period.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 25
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3536-108585

+ Details

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

- Definition

Cash received on stock transaction after deduction of issuance costs.

+ References

No definition available.

+ Details

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

- Definition

The number of shares issued or sold by the subsidiary or equity method investee per stock transaction.

+ References

No definition available.

+ Details

Name:	us-gaap_SaleOfStockNumberOfSharesIssuedInTransaction
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_SubsidiarySaleOfStockAxis=rgls_AtTheMomentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Stockholders' Equity (ATM Offering) (Details) - At The Moment - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Aug. 10, 2021	Dec. 12, 2018
Class of Stock [Line Items]
Commission fee rate						3.00%
Share sold (in shares)	0	0	16,017,131	0
Consideration received			$ 20.5
Payments for commissions			0.8
Amount eligible to be drawn down under the ATM	$ 50.0		$ 50.0		$ 50.0