Fair Value of Financial Instruments (Carrying Value and Estimated Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Investments
Held-to-maturity securities	$ 150	$ 150
Trading securities	20,003	20,034
Fair Value
Investments
Other long-term investments	49,966	51,769
Short-term investments	175	175
Cash and cash equivalents	98,610	89,194
Corporate-owned life insurance	3,759	2,592
Fair Value \| Discontinued Operations
Investments
Mortgage loans	3,690	3,895
Policy loans	5,770	5,366
Other long-term investments	16,299	15,780
Cash and cash equivalents	30,751	21,659
Policy reserves
Annuity (accumulations)	617,819	646,764
Annuity (benefit payments)	144,901	144,283
Fair Value \| Fixed maturities:
Investments
Held-to-maturity securities	150	150
Available-for-sale securities	1,498,662	1,453,286
Trading securities	13,673	14,390
Fair Value \| Fixed maturities: \| Discontinued Operations
Investments
Held-to-maturity securities	39	49
Available-for-sale securities	1,426,991	1,444,840
Fair Value \| Equity securities:
Investments
Available-for-sale securities	269,341	246,370
Trading securities	6,330	5,644
Fair Value \| Equity securities: \| Discontinued Operations
Investments
Available-for-sale securities	22,616	24,046
Carrying Value
Investments
Other long-term investments	49,966	51,769
Short-term investments	175	175
Cash and cash equivalents	98,610	89,194
Corporate-owned life insurance	3,759	2,592
Carrying Value \| Discontinued Operations
Investments
Mortgage loans	3,504	3,706
Policy loans	5,770	5,366
Other long-term investments	16,299	15,870
Cash and cash equivalents	30,751	21,659
Policy reserves
Annuity (accumulations)	620,037	666,711
Annuity (benefit payments)	95,086	95,129
Carrying Value \| Fixed maturities:
Investments
Held-to-maturity securities	150	150
Available-for-sale securities	1,498,662	1,453,286
Trading securities	13,673	14,390
Carrying Value \| Fixed maturities: \| Discontinued Operations
Investments
Held-to-maturity securities	38	48
Available-for-sale securities	1,426,991	1,444,840
Carrying Value \| Equity securities:
Investments
Available-for-sale securities	269,341	246,370
Trading securities	6,330	5,644
Carrying Value \| Equity securities: \| Discontinued Operations
Investments
Available-for-sale securities	$ 22,616	$ 24,046

Liability For Annuity Accumulations, Fair Value Disclosure

No definition available.

Name:	ufcs_LiabilityForAnnuityAccumulationsFairValueDisclosure
Namespace Prefix:	ufcs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Liability for Annuity Benefit Payments, Fair Value Disclosure

+ References

No definition available.

+ Details

Name:	ufcs_LiabilityForAnnuityBenefitPaymentsFairValueDisclosure
Namespace Prefix:	ufcs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Other Long-term Investments, Fair Value Disclosure

+ References

No definition available.

+ Details

Name:	ufcs_OtherLongTermInvestmentsFairValueDisclosure
Namespace Prefix:	ufcs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Policy Loan, Fair Value Disclosure

+ References

No definition available.

+ Details

Name:	ufcs_PolicyLoanFairValueDisclosure
Namespace Prefix:	ufcs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Short-term Investments, Fair Value Disclosure

+ References

No definition available.

+ Details

Name:	ufcs_ShortTermInvestmentsFairValueDisclosure
Namespace Prefix:	ufcs_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 25
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=75030427&loc=d3e22054-111558

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562

+ Details

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

- Definition

Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

+ References

No definition available.

+ Details

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

- Definition

Fair value portion of the amount that could be realized under a life insurance contract or contracts owned by the entity, commonly known as corporate-owned life insurance (COLI) or bank-owned life insurance (BOLI).

+ References

No definition available.

+ Details

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

- Definition

Fair value of investments in debt securities classified as held-to-maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (f)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 5
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27232-111563

+ Details

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

- References

No definition available.

+ Details

Name:	us-gaap_InvestmentsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

Name:	us-gaap_LiabilityForFuturePolicyBenefitsAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value portion of mortgage loans held-for-sale.

+ References

No definition available.

+ Details

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

- Definition

Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26626-111562

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.4)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26610-111562

+ Details

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

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_EstimateOfFairValueFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementOperatingActivitiesSegmentAxis=us-gaap_SegmentDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_FixedMaturitiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InvestmentTypeAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByMeasurementBasisAxis=us-gaap_CarryingReportedAmountFairValueDisclosureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: