Summary of Investments (Net Realized Investment Gains and Losses and Proceeds) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Net realized investment gains (losses):
Available-for-sale	$ (30)	$ 150
Allowance for credit losses	(59)	0
Trading securities
Change in fair value	(2,608)	1,746
Sales	151	0
Equity securities
Change in fair value	(90,647)	24,634
Sales	(181)	198
Mortgage loans allowance for credit losses	(5)	(15)
Cash equivalents	0	0
Real estate	(28)	0
Total net realized investment gains (losses)	(93,407)	26,713
Proceeds from sales	11,910	36,490
Gross realized gains	172	30
Gross realized losses	$ 382	$ 13

Gain (Loss) On Cash Equivalents

No definition available.

Name:	ufcs_GainLossOnCashEquivalents
Namespace Prefix:	ufcs_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of expense (reversal of expense) for expected credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), from change in present value of expected cash flows.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82922868-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=118955579&loc=SL82922897-210455