Schedule II. Condensed Financial Statements of Parent Company (Condensed Statement of Income and Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues
Investment income	$ 55,778	$ 39,670	$ 60,414
Total revenues	1,066,191	1,068,627	1,201,165
Expenses
Net income (loss)	80,594	(112,706)	14,820
Other comprehensive income (loss)
Change in unrealized appreciation on investments held by subsidiary	(39,901)	47,054	70,127
Change in liability for underfunded employee benefit plans of subsidiary	19,633	18,456	(20,924)
Other comprehensive income (loss), before tax and reclassification adjustments	(20,268)	65,510	49,203
Income tax effect	4,260	(13,757)	(10,334)
Reclassification adjustment for net (gains) losses included in income	(2,256)	(1,750)	1,521
Reclassification adjustment for employee benefit costs included in expense	6,603	4,289	4,497
Total reclassification adjustments, before tax	4,347	2,539	6,018
Income tax effect	(913)	(534)	(1,263)
Comprehensive income (loss)	68,020	(58,948)	58,444
United Fire Group, Inc.
Revenues
Investment income	23	141	295
Total revenues	23	141	295
Expenses
Other operating expenses	3	10	86
Total expenses	3	10	86
Income before income taxes and equity in net income of subsidiary	20	131	209
Federal income tax expense (benefit)	5	68	44
Net income before equity in net income (loss) of subsidiary	15	63	165
Equity in net income (loss) of subsidiary	80,579	(112,769)	14,655
Net income (loss)	80,594	(112,706)	14,820
Other comprehensive income (loss)
Change in unrealized appreciation on investments held by subsidiary	(39,901)	47,054	70,127
Change in liability for underfunded employee benefit plans of subsidiary	19,633	18,456	(20,924)
Other comprehensive income (loss), before tax and reclassification adjustments	(20,268)	65,510	49,203
Income tax effect	4,260	(13,757)	(10,334)
Other comprehensive income (loss), after tax, before reclassification adjustments	(16,008)	51,753	38,869
Reclassification adjustment for net (gains) losses included in income	(2,256)	(1,750)	1,521
Reclassification adjustment for employee benefit costs included in expense	6,603	4,289	4,497
Total reclassification adjustments, before tax	4,347	2,539	6,018
Income tax effect	(913)	(534)	(1,263)
Total reclassification adjustments, after tax	3,434	2,005	4,755
Comprehensive income (loss)	$ 68,020	$ (58,948)	$ 58,444