Note 9 - Commitments and Contingencies (Details Textual) $ in Thousands	6 Months Ended
Jun. 30, 2022 USD ($)
Long-term Incentive Plan, Payments	$ 0
Deferred Compensation Liability, Current and Noncurrent, Total	0
Employee and Severance Agreement, Maximum Aggregate Exposure	$ 800
Minimum [Member]
Long-term Incentive Plan, Bonus Pool Percent	1.00%
Maximum [Member]
Long-term Incentive Plan, Bonus Pool Percent	1.30%
Private Equity Funds [Member]
Guarantor Obligations, Current Carrying Value	$ 3,800

Represents maximum aggregate exposure for employee and severance agreement.

No definition available.

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Namespace Prefix:	sfe_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents amount of payments under long-term incentive plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	sfe_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents bonus pool percent for long-term incentive plan.

+ References

No definition available.

+ Details

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Namespace Prefix:	sfe_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Aggregate carrying value as of the balance sheet date of the liabilities for all deferred compensation arrangements. Represents currently earned compensation under compensation arrangements that is not actually paid until a later date.

+ References

No definition available.

+ Details

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

- Definition

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=124440162&loc=d3e12069-110248

+ Details

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

- Details

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Namespace Prefix:
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Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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Namespace Prefix:
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Period Type: