XML 83 R76.htm IDEA: XBRL DOCUMENT
v3.25.2

Treasury Stock - Additional Information (Detail) - shares | 3 Months Ended | 6 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024 | Dec. 31, 2024 | Dec. 12, 2024 | Nov. 18, 2024 | Apr. 11, 2024 | Nov. 18, 2023
Equity Class Of Treasury Stock [Line Items] |  |  |  |  |  |  |  |  |
Percentage of repurchase of Common Stock |  |  |  |  |  |  |  | 10.00% |
Number of shares authorized for repurchase |  |  |  |  |  |  |  | 507,707 |
Vested restricted stock award surrendered in lieu of cash payment |  |  |  |  |  |  | 584 |  | 549
Treasury Stock, Shares outstanding | 597,999 |  | 597,999 |  | 519,243 |  |  |  |
Common Stock [Member] |  |  |  |  |  |  |  |  |
Equity Class Of Treasury Stock [Line Items] |  |  |  |  |  |  |  |  |
Percentage of additional outstanding shares repurchase |  |  |  |  |  | 5.00% |  |  |
Shares repurchased under stock repurchase program | 481,967 |  | 481,967 |  | 403,211 |  |  |  |
Treasury stock activity (shares) | 23,940 | 235,719 | 78,756 | 235,719 |  |  |  |  |
Common Stock [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |
Equity Class Of Treasury Stock [Line Items] |  |  |  |  |  |  |  |  |
Number of shares authorized for repurchase |  |  |  |  |  | 228,858 |  |  |

X
- Definition Percentage of additional outstanding shares repurchase. + References No definition available. + Details
Name: | fsea_PercentageOfAdditionalOutstandingSharesRepurchase
Namespace Prefix: | fsea_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Percentage of Common stock repurchase + References No definition available. + Details
Name: | fsea_PercentageOfCommonStockRepurchase
Namespace Prefix: | fsea_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Shares repurchased under stock repurchase program. + References No definition available. + Details
Name: | fsea_SharesRepurchasedUnderStockRepurchaseProgram
Namespace Prefix: | fsea_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition It represents the number of treasury stock shares outstanding. + References No definition available. + Details
Name: | fsea_TreasuryStockSharesOutstanding
Namespace Prefix: | fsea_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Vested restricted stock award surrendered in lieu of a cash payment. + References No definition available. + Details
Name: | fsea_VestedRestrictedStockAwardSurrenderedInLieuOfACashPayment
Namespace Prefix: | fsea_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of shares authorized to be purchased under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 505 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481520/505-30-50-4 + Details
Name: | srt_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix: | srt_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

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

X
- Definition Number of shares remaining authorized to be purchased under share repurchase plan. Includes, but is not limited to, repurchase of stock and unit of ownership. + References No definition available. + Details
Name: | us-gaap_StockRepurchaseProgramRemainingNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of shares that have been repurchased during the period and are being held in treasury. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 10 -Topic 505 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481112/505-10-50-2 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 210 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(29)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480566/210-10-S99-1 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 505 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480008/505-10-S99-1 + Details
Name: | us-gaap_TreasuryStockSharesAcquired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_CommonStockMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |