EMPLOYEE BENEFIT PLANS - Asset Allocations (Details) - AB Qualified Retirement Plan	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations (as a percent)	100.00%	100.00%
Fixed Maturities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations (as a percent)	15.00%	18.00%
Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations (as a percent)	66.00%	61.00%
Other
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, actual plan asset allocations (as a percent)	19.00%	21.00%