STOCK-BASED COMPENSATION (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 Plan	Mar. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock option plans	2
Recognized compensation expense before tax	$ 63,980	$ 77,287
Recognized compensation expense, net of tax	$ 43,194	$ 52,695
Number of restricted stock shares granted during period (in shares)	57,720
Options exercised during period (in shares)	114,122
Weighted average exercise price of options exercised during period (in dollars per share)	$ 20.31
Non-Employee Director Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Registered shares (in shares)	200,000
Deregistered shares	148,204
Fair market value to purchase stock under Non-employee director stock option plan (in hundredths)	75.00%
Minimum cash retainer used to purchase common stock (in hundredths)	25.00%
Maximum cash retainer used to purchase common stock (in hundredths)	100.00%
Employers Mutual Casualty Company Incentive Stock Option 1993 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Deregistered shares	105,120
Employers Mutual Casualty Company Incentive Stock Option 2003 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Registered shares (in shares)	1,500,000
Time limit for granting awards	10 years
Vesting period of stock options	5 years
Employers Mutual Casualty Company Stock Incentive 2007 Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Registered shares (in shares)	2,000,000
Time limit for granting awards	10 years
Vesting period of stock options	5 years