EMPLOYEE RETIREMENT PLANS (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2019
Pension plans [Member] | Emc Insurance Companies [Member]
Components of net periodic benefit cost [Abstract]
Service cost	$ 4,071	$ 4,126
Interest cost	2,949	2,665
Expected return on plan assets	(5,440)	(5,978)
Amortization of net actuarial loss	598	125
Net periodic benefit cost (income)	2,178	938
Pension plans [Member] | EMC Insurance Group, Inc. [Member]
Components of net periodic benefit cost [Abstract]
Net periodic benefit cost (income)	653	282
Postretirement benefit plans [Member] | Emc Insurance Companies [Member]
Components of net periodic benefit cost [Abstract]
Service cost	353	368
Interest cost	546	521
Expected return on plan assets	(1,095)	(1,204)
Amortization of net actuarial loss	245	234
Amortization of prior service cost (credit)	(2,285)	(2,782)
Net periodic benefit cost (income)	(2,236)	(2,863)
Postretirement benefit plans [Member] | EMC Insurance Group, Inc. [Member]
Components of net periodic benefit cost [Abstract]
Net periodic benefit cost (income)	(636)	$ (806)
Entity's share of estimated contributions to employee benefit plan	$ 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