Schedule II. Condensed Financial Statements of Parent Company (Condensed Balance Sheet) (Phantom) (Details) - USD ($) $ / shares in Units, $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Condensed Balance Sheet Statements, Captions [Line Items]
Held-to-maturity fixed maturities	$ 199	$ 675
Common stock, par value per share (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	75,000,000	75,000,000
Common stock, shares issued (in shares)	25,429,769	25,151,428
Common stock, shares outstanding (in shares)	25,429,769	25,151,428
United Fire Group, Inc.
Condensed Balance Sheet Statements, Captions [Line Items]
Held-to-maturity fixed maturities	$ 150	$ 150
Common stock, par value per share (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	75,000,000	75,000,000
Common stock, shares issued (in shares)	25,429,769	25,151,428
Common stock, shares outstanding (in shares)	25,429,769	25,151,428