Employee Benefits (Asset Allocation) (Details) (Pension Plan [Member], USD $) In Thousands, unless otherwise specified				12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended		12 Months Ended
Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Corporate Bonds [Member]	Dec. 31, 2011 Corporate Bonds [Member]	Dec. 31, 2012 Redeemable Preferred Stocks [Member]	Dec. 31, 2011 Redeemable Preferred Stocks [Member]	Dec. 31, 2012 United Fire Common Stock [Member]	Dec. 31, 2011 United Fire Common Stock [Member]	Dec. 31, 2012 Unaffiliated Common Stock [Member]	Dec. 31, 2011 Unaffiliated Common Stock [Member]	Dec. 31, 2012 Arbitrage Fund [Member]	Dec. 31, 2011 Arbitrage Fund [Member]	Dec. 31, 2012 United Life Annuity [Member]	Dec. 31, 2011 United Life Annuity [Member]	Dec. 31, 2012 Cash and Cash Equivalents [Member]	Dec. 31, 2011 Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 75,276	$ 65,267	$ 62,730	$ 4,830	$ 4,000	$ 1,113	$ 2,067	$ 0	$ 4,078	$ 41,091	$ 34,085	$ 5,363	$ 5,239	$ 7,900	$ 7,803	$ 14,979	$ 7,995
Actual % of Total	100.00%	100.00%		6.40%	6.10%	1.50%	3.20%	0.00%	6.30%	54.60%	52.20%	7.10%	8.00%	10.50%	12.00%	19.90%	12.20%
Target Allocation, Minimum Percentage				0.00%		0.00%		0.00%		50.00%		0.00%		10.00%		10.00%
Target Allocations, Maximum Percentage				10.00%		5.00%		10.00%		70.00%		10.00%		20.00%		25.00%

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Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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- Definition

Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis.

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Target allocation minimum percentage of investments of this type to total plan assets presented on a weighted average basis.

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Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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