STOCK-BASED COMPENSATION (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) Plan $ / shares shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of stock option plans | Plan	2
Recognized compensation expense | $	$ 788	$ 500	$ 357
Recognized compensation expense, net of tax | $	512	325	233
Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost associated with restricted stock awards, not currently vested | $	$ 1,100
Weighted-average period over which the compensation expense is expected to be recognized	2 years 3 months 31 days
Total fair value of restricted stock awards that vested | $	$ 414	$ 233	$ 110
Non-vested restricted stock awards activity in shares
Non-vested, beginning of year (in shares)	216,944	155,864	85,002
Granted (in shares)	118,588	117,146	94,146
Vested (in shares)	(69,057)	(40,941)	(21,223)
Forfeited (in shares)	(32,194)	(15,125)	(2,061)
Non-vested, end of year (in shares)	234,281	216,944	155,864
Non-vested restricted stock awards activity in dollars per share weighted-average grant-date fair value
Non-vested, beginning of year (in dollars per share) | $ / shares	$ 20.40	$ 19.21	$ 17.27
Granted (in dollars per share) | $ / shares	24.56	21.36	20.49
Vested (in dollars per share) | $ / shares	19.98	18.99	17.27
Forfeited (in dollars per share) | $ / shares	22.73	19.35	17.74
Non-vested, end of year (in dollars per share) | $ / shares	$ 22.31	$ 20.40	$ 19.21
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	5 years	5 years	5 years
Unrecognized compensation cost associated with option awards, not currently vested | $	$ 7
Weighted-average period over which the compensation expense is expected to be recognized	1 month 30 days
Total intrinsic value of options exercised under Employers Mutual's stock option plans | $	$ 1,100	$ 770	$ 606
Portion of the current tax deduction realized from exercises of stock options | $	$ 284	$ 121	$ 152
Number of options [Roll Forward]
Outstanding, beginning of year (in shares)	1,006,171	1,351,802	1,702,938
Exercised (in shares)	(321,312)	(323,486)	(300,479)
Expired (in shares)	(34,947)	(20,850)	(34,421)
Forfeited (in shares)	(900)	(1,295)	(16,236)
Outstanding, end of year (in shares)	649,012	1,006,171	1,351,802
Options Exercisable, end of year (in shares)	593,224	824,365	963,831
Weighted-average exercise price [Roll Forward]
Outstanding, beginning of year (in dollars per share) | $ / shares	$ 14.92	$ 14.89	$ 14.78
Exercised (in dollars per share) | $ / shares	15.31	14.86	14.24
Expired (in dollars per share) | $ / shares	16.32	14.11	15.01
Forfeited (in dollars per share) | $ / shares	13.99	14.68	15.29
Outstanding, end of year (in dollars per share) | $ / shares	14.65	14.92	14.89
Exercisable, end of year (in dollars per share) | $ / shares	$ 14.72	$ 14.95	$ 14.94
Additional information relating to options outstanding and options vested (exercisable) [Abstract]
Options outstanding, Number of options (in shares)	649,012
Options outstanding, Weighted-average exercise price (in dollars per share) | $ / shares	$ 14.65
Options outstanding, Aggregate intrinsic value | $	$ 9,691
Options outstanding, Weighted-average remaining term	3 years 3 months 29 days
Options exercisable, Number of options (in shares)	593,224
Options exercisable, Weighted-average exercise price (in dollars per share) | $ / shares	$ 14.72
Options exercisable, Aggregate intrinsic value | $	$ 8,821
Options exercisable, Weighted-average remaining term	3 years 1 month 27 days
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Registered shares (in shares)	750,000	750,000	750,000
Fair market value of the stock on the date of purchase (in hundredths)	85.00%	85.00%	85.00%
Employee stock purchase plan administrative expense | $	$ 78	$ 59	$ 35
Other Stock Purchase Plan Shares Activity [Roll Forward]
Shares available for purchase, beginning of year (in shares)	414,883	471,459	508,749
Shares purchased under the plan (in shares)	(65,479)	(56,576)	(37,290)
Shares available for purchase, end of year (in shares)	349,404	414,883	471,459
Other stock purchase plan stock option exercise price range lower range limit (in dollars per share) | $ / shares	$ 21.78
Other stock purchase plan stock option exercise price range upper range limit (in dollars per share) | $ / shares	$ 23.42
Non-Employee Director Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Registered shares (in shares)	300,000	300,000	300,000
Fair market value to purchase stock under Non-employee director stock option plan (in hundredths)	75.00%	75.00%	75.00%
Minimum cash retainer used to purchase common stock (in hundredths)	25.00%	25.00%	25.00%
Maximum cash retainer used to purchase common stock (in hundredths)	100.00%	100.00%	100.00%
Non employee director stock option plan administrative expense | $	$ 84	$ 62	$ 49
Other Stock Purchase Plan Shares Activity [Roll Forward]
Shares available for purchase, beginning of year (in shares)	264,446	279,809	294,248
Shares purchased under the plan (in shares)	(14,603)	(15,363)	(14,439)
Shares available for purchase, end of year (in shares)	249,843	264,446	279,809
Other stock purchase plan stock option exercise price range lower range limit (in dollars per share) | $ / shares	$ 18.26
Other stock purchase plan stock option exercise price range upper range limit (in dollars per share) | $ / shares	$ 20.99
Dividend Reinvestment Plan [Member]
Other Stock Purchase Plan Shares Activity [Roll Forward]
Shares available for purchase, beginning of year (in shares)	976,697	982,227	988,436
Shares purchased under the plan (in shares)	(5,475)	(5,530)	(6,209)
Shares available for purchase, end of year (in shares)	971,222	976,697	982,227
Other stock purchase plan stock option exercise price range lower range limit (in dollars per share) | $ / shares	$ 22.09	$ 21.02	$ 18.69
Other stock purchase plan stock option exercise price range upper range limit (in dollars per share) | $ / shares	$ 30.50	$ 26.43	$ 23.59
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)	2,250,000	2,250,000	2,250,000
Time limit for granting awards	10 years	10 years	10 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)	3,000,000	3,000,000	3,000,000
Time limit for granting awards	10 years	10 years	10 years
Employee [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years	4 years	4 years
Non-Employee Director [Member] | Restricted Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Age To Attain Automatic Vesting	75 years
Non-vested restricted stock awards activity in shares
Granted (in shares)	2,000