Servicing Assets and Liabilities - Narrative (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
SBA/USDA loans
Schedule Of Servicing Asset [Line Items]
Loans serviced for others not included in balance sheet	$ 428,000	$ 402,000
Contractually specified servicing fees earned by United on servicing rights	3,900	3,770	$ 3,820
Residential mortgage servicing rights
Schedule Of Servicing Asset [Line Items]
Loans serviced for others not included in balance sheet	2,820,000	2,310,000
Contractually specified servicing fees earned by United on servicing rights	6,480	4,820	$ 3,670
Equipment financing loans
Schedule Of Servicing Asset [Line Items]
Loans serviced for others not included in balance sheet	78,800	45,500
Servicing liabilities	$ 675	$ 357

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- Definition

Amount of contractually specified servicing fee, late fee, and ancillary fee recognized as income for servicing asset and servicing liability.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=125521744&loc=d3e122596-111746

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- Definition

Amount of transferred financial assets in which the transferor has continuing involvement with the assets underlying the transaction that have been derecognized. Continuing involvement includes, but is not limited to, servicing, recourse, and restrictions on transferor's interests in transferred financial assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=121570589&loc=d3e107314-111719

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- Definition

Aggregate amount of servicing liabilities that are subsequently measured at fair value and servicing liabilities that are subsequently measured using the amortization method.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

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