SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Narratives) (Details) (USD $)	3 Months Ended															12 Months Ended								12 Months Ended				0 Months Ended	12 Months Ended	0 Months Ended	12 Months Ended
	Dec. 31, 2013		Sep. 30, 2013	Jun. 30, 2013		Mar. 31, 2013		Dec. 31, 2012		Sep. 30, 2012		Jun. 30, 2012		Mar. 31, 2012		Dec. 31, 2013	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2012 Accounting Standards Update 2010-26 [Member]	Feb. 01, 2012 United Fire & Casualty Company [Member] Febuary 2012 Reorganization [Member]	Dec. 31, 2013 United Fire Group, Inc. [Member]	Dec. 31, 2012 United Fire Group, Inc. [Member]		Feb. 01, 2012 United Fire Group, Inc. [Member] Febuary 2012 Reorganization [Member]	Mar. 28, 2011 Mercer Insurance Group [Member]	Dec. 31, 2011 Mercer Insurance Group [Member]	Mar. 28, 2011 Mercer Insurance Group [Member] Payments to the Former Executive Officers [Member]	Dec. 31, 2013 Property and Casualty Insurance [Member] states	Dec. 31, 2012 Property and Casualty Insurance [Member]	Dec. 31, 2011 Property and Casualty Insurance [Member]	Dec. 31, 2013 Life Insurance [Member] states	Dec. 31, 2012 Life Insurance [Member]	Dec. 31, 2011 Life Insurance [Member]	Dec. 31, 2013 Building [Member]	Dec. 31, 2012 Building [Member]	Dec. 31, 2013 Land [Member]	Dec. 31, 2012 Land [Member]	Dec. 31, 2013 Furniture and Fixtures [Member]	Dec. 31, 2012 Furniture and Fixtures [Member]	Dec. 31, 2013 Computer Equipment and Software [Member]	Dec. 31, 2012 Computer Equipment and Software [Member]	Dec. 31, 2013 Airplane [Member]	Dec. 31, 2012 Airplane [Member]
Item Effected [Line Items]
Number of states in which we are licensed as insurer																															43			37
Business Combinations [Abstract]
Percentage of outstanding common stock acquired																												100.00%
Total consideration of business combination																												$ 191,475,000
Short-term debt used for acquisition funding																												79,900,000
Transaction costs																												8,318,000	11,900,000	5,540,000
Common stock, par value per share (in usd per share)	$ 0.001							$ 0.001								$ 0.001	$ 0.001						$ 3.3333333	$ 0.001	$ 0.001		$ 0.001
Percentage of the gains and profits from the Lloyds plan available to United Fire & Indemnity Company																100.00%
Traditional life insurance, interest rate assumptions, lower range																																		4.50%
Traditional life insurance, interest rate assumptions, upper range																																		6.00%
Securities on deposit as required by law	1,620,505,000							1,736,466,000								1,620,505,000	1,736,466,000
Other-than-temporary impairment charges																139,000	4,000		395,000
Payment for income taxes																13,628,000	11,920,000		570,000
Federal tax refund received																8,744,000	15,798,000
Interest payment																0	961,000		1,926,000
Increase (decrease) in DAC asset	3,407,000							(38,695,000)								3,407,000	(38,695,000)
Income Statement Impact of Updated Accounting Guidance on a Prospective Basis [Abstract]
Additional expense on pretax basis																775,140,000	767,169,000		717,723,000			10,291,000
Increase to other underwriting expenses																89,861,000	81,125,000		58,757,000			25,528,000
Decrease to amortization of deferred policy acquisition recoverability																(153,677,000)	(140,161,000)		(127,413,000)			15,237,000									(147,175,000)	(132,771,000)	(118,189,000)	(6,502,000)	(7,390,000)	(9,224,000)
Decrease to net income	(26,526,000)		(11,725,000)	(15,496,000)		(22,393,000)		2,418,000		(8,730,000)		(14,716,000)		(19,184,000)		(76,140,000)	(40,212,000)		(11,000)			6,689,000		(76,140,000)	(40,212,000)	[1],[2]			14,650,000		(67,456,000)	(33,512,000)	7,639,000	(8,684,000)	(6,700,000)	(7,650,000)
Decrease to net income per share (in usd per share)	$ (1.04)	[3]	$ (0.46)	$ (0.61)	[3]	$ (0.89)	[3]	$ 0.10	[3]	$ (0.34)	[3]	$ (0.58)	[3]	$ (0.75)	[3]	$ (3.01)	$ (1.58)	[3]	$ 0.00			$ 0.26
Property and equipment	47,218,000							43,090,000								47,218,000	43,090,000																				29,072,000	25,186,000	7,163,000	6,879,000	2,707,000	1,024,000	3,197,000	3,076,000	5,079,000	6,925,000
Depreciation expense																4,391,000	5,440,000		3,661,000
Useful life of intangible assets																				2 years	15 years
Amortization expense																															$ 1,212,000	$ 2,539,000	$ 1,922,000

[1] The Condensed Statement of Cash Flows includes the full year 2012 results. The results of January 2012 are immaterial to the full year 2012 results.

[2] The Condensed Statement of Income and Comprehensive Income includes the full year 2012 results. The results of January 2012 are immaterial to the full year 2012 results.

[3] The sum of the quarterly reported amounts may not equal the full year, as each is computed independently.