Deposit (Schedule of deposit liabilities) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Non-interest bearing deposits	$ 423,970	$ 427,670
Non-Interest bearing deposits, percentage	28.00%	28.00%
Interest bearing deposits	$ 1,113,101	$ 1,123,307
Total deposits	$ 1,537,071	$ 1,550,977
Non-Interest and Interest bearing deposits, percentage	100.00%	100.00%
Demand Deposit Liability [Member]
Interest bearing deposits	$ 373,046	$ 350,860
Interest bearing deposits, percentage	24.00%	22.00%
Money Market Liability [Member]
Interest bearing deposits	$ 401,628	$ 385,649
Interest bearing deposits, percentage	26.00%	25.00%
Savings Deposit Liability [Member]
Interest bearing deposits	$ 180,030	$ 191,265
Interest bearing deposits, percentage	12.00%	12.00%
Time Deposit Retail Liability [Member]
Interest bearing deposits	$ 143,397	$ 165,533
Interest bearing deposits, percentage	9.00%	11.00%
Time Deposit Brokered Liability [Member]
Interest bearing deposits	$ 15,000	$ 30,000
Interest bearing deposits, percentage	1.00%	2.00%

Percentage of aggregate liabilities related to interest bearing deposits.

No definition available.

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- Definition

Percentage of aggregate liabilities related to non-interest and interest bearing deposits.

+ References

No definition available.

+ Details

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- Definition

Percentage of aggregate liabilities related to non interest bearing deposits.

+ References

No definition available.

+ Details

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Namespace Prefix:	func_
Data Type:	dtr-types:percentItemType
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- Definition

The aggregate of all domestic interest-bearing and noninterest-bearing deposit liabilities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

+ Details

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- Definition

Total amount of interest-bearing domestic deposit liabilities, which may include brokered, retail, demand, checking, notice of withdrawal, money market and other interest-bearing deposits.

+ References

+ Details

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- Definition

Amount of domestic noninterest-bearing deposits held by the entity, which may include demand deposits, checking, brokered and retail deposits.

+ References

+ Details

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- Details

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- Details

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- Details

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- Details

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- Details

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