8. Fair Value: Schedule of Inputs in Estimation of Fair Value of Level 3 Financial Instruments (Details) - USD ($)	9 Months Ended	12 Months Ended
Sep. 30, 2017	Dec. 31, 2016
Loans held at fair value	$ 4,644,549	$ 4,207,338
Servicing asset	329,753	312,814
Loans Held At Fair Value
Balance at beginning	4,207,000
Origination of loans/additions	437,000
Principal repayments/amortization	(126,000)
Change in fair value of financial instruments	127,000
Balance at ending	4,645,000	4,207,000
Servicing asset [Member]
Balance at beginning	313,000
Origination of loans/additions	39,000
Principal repayments/amortization	(27,000)
Change in fair value of financial instruments	5,000
Balance at ending	330,000	313,000
Fair Value, Inputs, Level 3
Loans held at fair value	4,645,000	4,207,000
Servicing asset	$ 330,000	$ 313,000
Fair Value, Inputs, Level 3 \| Loans Held At Fair Value
Principal valuation technique	Discounted cash flow	Discounted cash flow
Fair Value, Inputs, Level 3 \| Loans Held At Fair Value \| Fair Value, Measurements, Recurring \| Minimum
Constant prepayment rate	7.73%	7.53%
Weighted average discount rate	8.68%	8.11%
Weighted average life	3 years 1 month 16 days	3 years 18 days
Projected default rate	0.72%	0.77%
Fair Value, Inputs, Level 3 \| Loans Held At Fair Value \| Fair Value, Measurements, Recurring \| Maximum
Constant prepayment rate	9.76%	9.62%
Weighted average discount rate	10.80%	10.58%
Weighted average life	9 years 9 months 7 days	9 years 11 months 12 days
Projected default rate	5.17%	6.64%
Fair Value, Inputs, Level 3 \| Servicing asset [Member]
Principal valuation technique	Discounted cash flow	Discounted cash flow
Fair Value, Inputs, Level 3 \| Servicing asset [Member] \| Fair Value, Measurements, Recurring \| Minimum
Constant prepayment rate	5.38%	4.89%
Weighted average discount rate	12.38%	10.50%
Weighted average life	3 years 1 month 16 days	3 years 18 days
Fair Value, Inputs, Level 3 \| Servicing asset [Member] \| Fair Value, Measurements, Recurring \| Maximum
Constant prepayment rate	9.79%	9.96%
Weighted average discount rate	17.25%	15.31%
Weighted average life	9 years 6 months 21 days	9 years 8 months 12 days

Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of increase (decrease) of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPeriodIncreaseDecrease
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

+ Details

Name:	us-gaap_LoansReceivableFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Aggregate amount of servicing assets that are subsequently measured at fair value and servicing assets 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

+ Details

Name:	us-gaap_ServicingAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(2)(i)
-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.D.2)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

+ Details

Name:	us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Constant prepayment rate.

+ References

No definition available.

+ Details

Name:	usbi_ConstantPrepaymentRate
Namespace Prefix:	usbi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Principal valuation technique.

+ References

No definition available.

+ Details

Name:	usbi_PrincipalValuationTechnique
Namespace Prefix:	usbi_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	usbi_ProjectedDefaultRate
Namespace Prefix:	usbi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Weighted average discount rate.

+ References

No definition available.

+ Details

Name:	usbi_WeightedAverageDiscountRate
Namespace Prefix:	usbi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FinancialInstrumentAxis=usbi_LoansHeldAtFairValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_AssetManagement1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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