Subsequent events (Details) - Subsequent Event - USD ($)	Jan. 21, 2016	Jan. 20, 2016
Subsequent Event [Line Items]
Operating leases, increase in future minimum payments due		$ 320,684
Security Deposit		$ 25,800
Increase in shares of common stock reserved for issuance (in shares)	717,755
Annual increase in shares of common stock reserved for issuance by percentage of stock outstanding (percent)	4.00%

Common Stock, Annual Increase in Capital Shares Reserved for Future Issuance by Percentage of Stock Outstanding

No definition available.

Name:	flks_CommonStockAnnualIncreaseinCapitalSharesReservedforFutureIssuancebyPercentageofStockOutstanding
Namespace Prefix:	flks_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Common Stock, Increase in Capital Shares Reserved for Future Issuance

+ References

No definition available.

+ Details

Name:	flks_CommonStockIncreaseinCapitalSharesReservedforFutureIssuance
Namespace Prefix:	flks_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Operating Leases, Increase (Decrease) in Future Minimum Payments Due

+ References

No definition available.

+ Details

Name:	flks_OperatingLeasesIncreaseDecreaseinFutureMinimumPaymentsDue
Namespace Prefix:	flks_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount of an asset, typically cash, provided to a counterparty to provide certain assurance of performance by the entity pursuant to the terms of a written or oral agreement, such as a lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.8,17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_SecurityDeposit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: