The number of warrants or rights exercised during period.

No definition available.

Name:	snca_ClassOfWarrantOrRightExercisedDuringPeriod
Namespace Prefix:	snca_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Exercise price per share of warrants or rights exercised during period.

+ References

No definition available.

+ Details

Name:	snca_ClassOfWarrantOrRightExercisedDuringPeriodExercisePrice
Namespace Prefix:	snca_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash inflow associated with the amount received from holders exercising their stock warrants.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

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

- Definition

Number of additional shares authorized for issuance under share-based payment arrangement.

+ References

No definition available.

+ Details

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

- Definition

Number of shares authorized for issuance under share-based payment arrangement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_ClassOfWarrantOrRightAxis=snca_StockPurchaseWarrantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_PlanNameAxis=snca_InducementAwardStockOptionPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Note 10 - Subsequent Events (Details Textual) - USD ($)		1 Months Ended	9 Months Ended		12 Months Ended
Note 10 - Subsequent Events (Details Textual) - USD ($)	Mar. 23, 2020	Jan. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018
Proceeds from Warrant Exercises			$ 3,547,894	$ 131	$ 236
Stock Purchase Warrants [Member]
Class of Warrant or Right, Exercised During Period (in shares)		5,555,554
Class of Warrant or Right, Exercised During Period, Exercise Price (in dollars per share)		$ 1.36
Proceeds from Warrant Exercises		$ 7,600,000
Subsequent Event [Member] \| Inducement Award Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in shares)	500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)	715,000
Subsequent Event [Member] \| Stock Purchase Warrants [Member]
Class of Warrant or Right, Exercised During Period (in shares)		5,555,554
Class of Warrant or Right, Exercised During Period, Exercise Price (in dollars per share)		$ 1.36
Proceeds from Warrant Exercises		$ 7,600,000