XML 36 R30.htm IDEA: XBRL DOCUMENT
v3.25.2

Investment Securities (Tables) | 6 Months Ended
--- | ---
Jun. 30, 2025
Investments, Debt and Equity Securities [Abstract] |
Schedule of Investment Securities Available-for-Sale and Held-to-Maturity | Details of investment securities available-for-sale and held-to-maturity as of June 30, 2025 and December 31, 2024 were as follows:
|  | Available-for-Sale |
|  | June 30, 2025 |
|  |  |  |  | Gross |  |  | Gross |  |  | Estimated |
|  | Amortized |  |  | Unrealized |  |  | Unrealized |  |  | Fair |
|  | Cost |  |  | Gains |  |  | Losses |  |  | Value |
|  | (Dollars in Thousands) |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |  |
Residential |  | $ | 89,461 |  |  | $ | 1,134 |  |  | $ | (1,638 | ) |  | $ | 88,957 |
Commercial |  |  | 10,431 |  |  |  | 88 |  |  |  | (145 | ) |  |  | 10,374 |
Obligations of U.S. government-sponsored agencies |  |  | 10,584 |  |  |  | 150 |  |  |  | (409 | ) |  |  | 10,325 |
Obligations of states and political subdivisions |  |  | 1,305 |  |  |  | — |  |  |  | (9 | ) |  |  | 1,296 |
Corporate notes |  |  | 17,760 |  |  |  | 45 |  |  |  | (1,270 | ) |  |  | 16,535 |
U.S. Treasury securities |  |  | 30,022 |  |  |  | — |  |  |  | (933 | ) |  |  | 29,089 |
Total |  | $ | 159,563 |  |  | $ | 1,417 |  |  | $ | (4,404 | ) |  | $ | 156,576 |
|  | Held-to-Maturity |
|  | June 30, 2025 |
|  |  |  |  | Gross |  |  | Gross |  |  | Estimated |
|  | Amortized |  |  | Unrealized |  |  | Unrealized |  |  | Fair |
|  | Cost |  |  | Gains |  |  | Losses |  |  | Value |
|  | (Dollars in Thousands) |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |  |
Commercial |  | $ | 206 |  |  | $ | — |  |  | $ | (6 | ) |  | $ | 200 |
Obligations of U.S. government-sponsored agencies |  |  | 344 |  |  |  | — |  |  |  | (19 | ) |  |  | 325 |
Obligations of states and political subdivisions |  |  | 11 |  |  |  | — |  |  |  | (1 | ) |  |  | 10 |
Total |  | $ | 561 |  |  | $ | — |  |  | $ | (26 | ) |  | $ | 535 |
|  | Available-for-Sale |
|  | December 31, 2024 |
|  |  |  |  | Gross |  |  | Gross |  |  | Estimated |
|  | Amortized |  |  | Unrealized |  |  | Unrealized |  |  | Fair |
|  | Cost |  |  | Gains |  |  | Losses |  |  | Value |
|  | (Dollars in Thousands) |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |  |
Residential |  | $ | 87,703 |  |  | $ | 347 |  |  | $ | (2,768 | ) |  | $ | 85,282 |
Commercial |  |  | 12,105 |  |  |  | 17 |  |  |  | (202 | ) |  |  | 11,920 |
Obligations of U.S. government-sponsored agencies |  |  | 11,436 |  |  |  | 18 |  |  |  | (620 | ) |  |  | 10,834 |
Obligations of states and political subdivisions |  |  | 1,577 |  |  |  | — |  |  |  | (28 | ) |  |  | 1,549 |
Corporate notes |  |  | 17,757 |  |  |  | 58 |  |  |  | (1,871 | ) |  |  | 15,944 |
U.S. Treasury securities |  |  | 44,019 |  |  |  | — |  |  |  | (1,660 | ) |  |  | 42,359 |
Total |  | $ | 174,597 |  |  | $ | 440 |  |  | $ | (7,149 | ) |  | $ | 167,888 |
|  | Held-to-Maturity |
|  | December 31, 2024 |
|  | Amortized Cost |  |  | Gross Unrealized Gains |  |  | Gross Unrealized Losses |  |  | Estimated Fair Value |
|  | (Dollars in Thousands) |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |  |
Commercial |  | $ | 264 |  |  | $ | — |  |  | $ | (10 | ) |  | $ | 254 |
Obligations of U.S. government-sponsored agencies |  |  | 384 |  |  |  | — |  |  |  | (27 | ) |  |  | 357 |
Obligations of states and political subdivisions |  |  | 34 |  |  |  | — |  |  |  | (3 | ) |  |  | 31 |
Total |  | $ | 682 |  |  | $ | — |  |  | $ | (40 | ) |  | $ | 642 |
Maturities of Investment Securities Available-for-Sale and Held-to-Maturity | The scheduled maturities of investment securities available-for-sale and held-to-maturity as of June 30, 2025 are presented in the following table:
|  | Available-for-Sale |  |  | Held-to-Maturity |
|  | Amortized Cost |  |  | Estimated Fair Value |  |  | Amortized Cost |  |  | Estimated Fair Value |
|  | (Dollars in Thousands) |
Maturing within one year |  | $ | 15,417 |  |  | $ | 15,223 |  |  | $ | — |  |  | $ | — |
Maturing after one to five years |  |  | 20,559 |  |  |  | 19,777 |  |  |  | 211 |  |  |  | 207 |
Maturing after five to ten years |  |  | 60,449 |  |  |  | 57,655 |  |  |  | 258 |  |  |  | 241 |
Maturing after ten years |  |  | 63,138 |  |  |  | 63,921 |  |  |  | 92 |  |  |  | 87 |
Total |  | $ | 159,563 |  |  | $ | 156,576 |  |  | $ | 561 |  |  | $ | 535 |
Schedule of Fair Value and Unrealized Loss on Investments for Securities for Which Allowance for Credit Losses has not been Recorded | The following tables reflect fair value and gross unrealized losses, aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, as of June 30, 2025 and December 31, 2024.
|  | Available-for-Sale |
|  | June 30, 2025 |
|  | Less than 12 Months |  |  | 12 Months or More |
|  | Fair Value |  |  | Unrealized Losses |  |  | Fair Value |  |  | Unrealized Losses |
|  | (Dollars in Thousands) |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |  |
Residential |  | $ | 4,707 |  |  | $ | (20 | ) |  | $ | 25,511 |  |  | $ | (1,618 | )
Commercial |  |  | 829 |  |  |  | (3 | ) |  |  | 4,538 |  |  |  | (142 | )
Obligations of U.S. government-sponsored agencies |  |  | — |  |  |  | — |  |  |  | 4,655 |  |  |  | (409 | )
Obligations of states and political subdivisions |  |  | — |  |  |  | — |  |  |  | 1,296 |  |  |  | (9 | )
Corporate notes |  |  | — |  |  |  | — |  |  |  | 14,490 |  |  |  | (1,270 | )
U.S. Treasury securities |  |  | — |  |  |  | — |  |  |  | 29,089 |  |  |  | (933 | )
Total |  | $ | 5,536 |  |  | $ | (23 | ) |  | $ | 79,579 |  |  | $ | (4,381 | )
|  | Held-to-Maturity |
|  | June 30, 2025 |
|  | Less than 12 Months |  |  | 12 Months or More |
|  | Fair Value |  |  | Unrealized Losses |  |  | Fair Value |  |  | Unrealized Losses |
|  | (Dollars in Thousands) |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |  |
Commercial |  | $ | — |  |  | $ | — |  |  | $ | 200 |  |  | $ | (6 | )
Obligations of U.S. government-sponsored agencies |  |  | — |  |  |  | — |  |  |  | 325 |  |  |  | (19 | )
Obligations of states and political subdivisions |  |  | — |  |  |  | — |  |  |  | 10 |  |  |  | (1 | )
Total |  | $ | — |  |  | $ | — |  |  | $ | 535 |  |  | $ | (26 | )
|  | Available-for-Sale |
|  | December 31, 2024 |
|  | Less than 12 Months |  |  | 12 Months or More |
|  | Fair Value |  |  | Unrealized Losses |  |  | Fair Value |  |  | Unrealized Losses |
|  | (Dollars in Thousands) |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |  |
Residential |  | $ | 41,417 |  |  | $ | (424 | ) |  | $ | 28,520 |  |  | $ | (2,344 | )
Commercial |  |  | 3,374 |  |  |  | (13 | ) |  |  | 5,331 |  |  |  | (189 | )
Obligations of U.S. government-sponsored agencies |  |  | 3,823 |  |  |  | (1 | ) |  |  | 4,457 |  |  |  | (619 | )
Obligations of states and political subdivisions |  |  | — |  |  |  | — |  |  |  | 1,549 |  |  |  | (28 | )
Corporate notes |  |  | — |  |  |  | — |  |  |  | 13,886 |  |  |  | (1,871 | )
U.S. Treasury securities |  |  | — |  |  |  | — |  |  |  | 42,359 |  |  |  | (1,660 | )
Total |  | $ | 48,614 |  |  | $ | (438 | ) |  | $ | 96,102 |  |  | $ | (6,711 | )
|  | Held-to-Maturity |
|  | December 31, 2024 |
|  | Less than 12 Months |  |  | 12 Months or More |
|  | Fair Value |  |  | Unrealized Losses |  |  | Fair Value |  |  | Unrealized Losses |
|  | (Dollars in Thousands) |
Mortgage-backed securities: |  |  |  |  |  |  |  |  |  |  |  |
Commercial |  | $ | — |  |  | $ | — |  |  | $ | 254 |  |  | $ | (10 | )
Obligations of U.S. government-sponsored agencies |  |  | — |  |  |  | — |  |  |  | 357 |  |  |  | (27 | )
Obligations of states and political subdivisions |  |  | — |  |  |  | — |  |  |  | 31 |  |  |  | (3 | )
Total |  | $ | — |  |  | $ | — |  |  | $ | 642 |  |  | $ | (40 | )

X
- Definition Tabular disclosure of investment securities available for sale and held to maturity. + References No definition available. + Details
Name: | fusb_ScheduleOfInvestmentSecuritiesAvailableForSaleAndHeldToMaturityTableTextBlock
Namespace Prefix: | fusb_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of maturities of an entity's investments as well as any other information pertinent to the investments. + References No definition available. + Details
Name: | us-gaap_InvestmentsClassifiedByContractualMaturityDateTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_InvestmentsDebtAndEquitySecuritiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of unrealized gains and losses on investments. + References No definition available. + Details
Name: | us-gaap_UnrealizedGainLossOnInvestmentsTableTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration