Schedule II. Condensed Financial Statements of Parent Company (Condensed Balance Sheet) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Held-to-maturity, at amortized cost (fair value $0 in 2018 and $150 in 2017)	$ 0	$ 150
Available-for-sale, at fair value (amortized cost $150 in 2018 and $0 in 2017)	1,749,488	1,535,070
Cash and cash equivalents	64,454	95,562
Federal income tax receivable	15,035	6,031
Accrued investment income	15,774	13,841
Total assets	2,816,698	4,183,431
Liabilities and stockholders' equity
Liabilities	1,928,323	3,210,058
Stockholders' equity
Common stock, $0.001 par value, authorized 75,000,000 shares; 25,097,408 and 24,916,806 issued and outstanding in 2018 and 2017, respectively	25	25
Additional paid-in capital	203,350	196,334
Retained earnings	715,472	608,700
Accumulated other comprehensive income, net of tax	(30,472)	168,314
Total stockholders' equity	888,375	973,373	$ 941,884	$ 878,897
Total liabilities and stockholders' equity	2,816,698	4,183,431
United Fire Group, Inc.
Assets
Held-to-maturity, at amortized cost (fair value $0 in 2018 and $150 in 2017)	0	150
Available-for-sale, at fair value (amortized cost $150 in 2018 and $0 in 2017)	150	0
Investment in subsidiary	877,893	967,590
Cash and cash equivalents	9,186	4,537
Federal income tax receivable	1,165	1,095
Accrued investment income	1	1
Total assets	888,395	973,373
Liabilities and stockholders' equity
Liabilities	20	0
Stockholders' equity
Common stock, $0.001 par value, authorized 75,000,000 shares; 25,097,408 and 24,916,806 issued and outstanding in 2018 and 2017, respectively	25	25
Additional paid-in capital	203,350	196,334
Retained earnings	715,472	608,700
Accumulated other comprehensive income, net of tax	(30,472)	168,314
Total stockholders' equity	888,375	973,373
Total liabilities and stockholders' equity	$ 888,395	$ 973,373