EMPLOYEE RETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2019
Pension plans [Member] | Emc Insurance Companies [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 3,806	$ 4,300	$ 7,877	$ 8,426
Interest cost	2,930	2,698	5,879	5,363
Expected return on plan assets	(5,423)	(6,048)	(10,863)	(12,026)
Amortization of net actuarial loss	548	143	1,146	268
Net periodic benefit cost (income)	1,861	1,093	4,039	2,031
Pension plans [Member] | EMC Insurance Group, Inc. [Member]
Components of net periodic benefit cost [Abstract]
Net periodic benefit cost (income)	559	327	1,212	609
Postretirement benefit plans [Member] | Emc Insurance Companies [Member]
Components of net periodic benefit cost [Abstract]
Service cost	352	368	705	736
Interest cost	545	521	1,091	1,042
Expected return on plan assets	(1,094)	(1,203)	(2,189)	(2,407)
Amortization of net actuarial loss	246	233	491	467
Amortization of prior service cost (credit)	(2,285)	(2,782)	(4,570)	(5,564)
Net periodic benefit cost (income)	(2,236)	(2,863)	(4,472)	(5,726)
Postretirement benefit plans [Member] | EMC Insurance Group, Inc. [Member]
Components of net periodic benefit cost [Abstract]
Net periodic benefit cost (income)	(635)	$ (806)	(1,271)	$ (1,612)
Entity's share of estimated contributions to employee benefit plan	$ 0		$ 0
Qualified pension plan [Member] | Emc Insurance Companies [Member]
Components of net periodic benefit cost [Abstract]
Defined Benefit Plan Estimated Future Parent Total Contributions Next Fiscal Year					$ 7,000