Leases - Maturities of Operating and Finance Lease Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Operating Lease Liabilities, Payments Due [Abstract]
Operating leases, 2023	$ 1,326
Operating leases, 2024	2,153
Operating leases, 2025	1,244
Operating leases, 2026	1,209
Operating leases, 2027	1,061
Operating leases, 2028 and thereafter	1,055
Total operating lease payments	8,048
Less imputed interest, Operating leases	1,559
Total operating lease liabilities	6,489
Finance Lease Liabilities, Payments, Due [Abstract]
Finance leases, 2023	1
Total finance lease payments	1
Total finance lease liabilities	1
Lessee Lease Liability Payments Due [Abstract]
2023	1,327
2024	2,153
2025	1,244
2026	1,209
2027	1,061
2028 and thereafter	1,055
Total lease payments	8,049
Less imputed interest	1,559
Total lease liabilities	6,490	$ 7,341
Sublease Income Payments Due [Abstract]
Subincome lease, 2023	(113)
Subincome lease, 2024	(231)
Subincome lease, 2025	(39)
Total sublease income payments (receipts)	$ (383)

Lessee lease liability.

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee lease liability payments due.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Lessee lease liability payments due.

+ References

No definition available.

+ Details

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Balance Type:	na
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- Definition

Lessee lease liability payments due year five.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Lessee lease liability payments due year five and after year five.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Lessee lease liability payments due year four.

+ References

No definition available.

+ Details

Name:	sien_LesseeLeaseLiabilityPaymentsDueYearFour
Namespace Prefix:	sien_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Lessee lease liability payments due year one.

+ References

No definition available.

+ Details

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Namespace Prefix:	sien_
Data Type:	xbrli:monetaryItemType
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- Definition

Lessee lease liability payments due year three.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Lessee lease liability payments due year two.

+ References

No definition available.

+ Details

Name:	sien_LesseeLeaseLiabilityPaymentsDueYearTwo
Namespace Prefix:	sien_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Lessee leases liability undiscounted excess amount.

+ References

No definition available.

+ Details

Name:	sien_LesseeLeasesLiabilityUndiscountedExcessAmount
Namespace Prefix:	sien_
Data Type:	xbrli:monetaryItemType
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- Definition

Lessee operating lease liability payments due year six.

+ References

No definition available.

+ Details

Name:	sien_LesseeOperatingLeaseLiabilityPaymentsDueYearSix
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Sublease income payments due.

+ References

No definition available.

+ Details

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- Definition

Sublease income payments due abstract.

+ References

No definition available.

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- Definition

Sublease income payments due next twelve months.

+ References

No definition available.

+ Details

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- Definition

Sublease income payments due year three.

+ References

No definition available.

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- Definition

Sublease income payments due year two.

+ References

No definition available.

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- References

No definition available.

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Name:	us-gaap_FinanceLeaseLiabilitiesPaymentsDueAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
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- Definition

Present value of lessee's discounted obligation for lease payments from finance lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 6
-URI https://asc.fasb.org/extlink&oid=128292326&loc=SL77918701-209980

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of lessee's undiscounted obligation for lease payments for finance lease.

+ References

+ Details

Name:	us-gaap_FinanceLeaseLiabilityPaymentsDue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Amount of lessee's undiscounted obligation for lease payment for finance lease to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

Name:	us-gaap_FinanceLeaseLiabilityPaymentsDueNextTwelveMonths
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

Amount of lessee's undiscounted obligation for lease payment for operating lease to be paid in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Amount of lessee's undiscounted obligation for lease payments in excess of discounted obligation for lease payments for operating lease.

+ References

+ Details

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- References

No definition available.

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

- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=123391704&loc=SL77918627-209977

+ Details

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