RETIREMENT BENEFITS - Fair Value of Plan Assets by Asset Category (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 807,016	$ 764,405
Fixed income securities
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	708,088	448,908
Equity securities—US
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	48,237	248,858
Equity securities—International
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	24,512	52,394
Cash and cash equivalents
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 26,179	$ 14,245