EMPLOYEE BENEFIT PLANS (Changes in Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension Plans
Change in benefit obligation:
Benefit obligation at beginning of year	$ 353.3	$ 329.3
Service cost	55.6	57.5	$ 59.0
Interest cost	7.9	5.3	6.9
Plan amendments	0.0	0.0
Benefit payments	(18.9)	(31.2)
Actuarial gain	(40.9)	(7.6)
Projected benefit obligation at end of year	357.0	353.3	329.3
Change in plan assets:
Fair value of plan assets at beginning of year	306.3	255.8
Actual return on plan assets	(51.0)	27.7
Benefits paid	(18.9)	(31.2)
Employer contributions	37.8	54.0
Fair value of plan assets at end of year	274.2	306.3	255.8
Reconciliation of funded status:
Fair value of plan assets at end of year	274.2	306.3	255.8
Less benefit obligations at end of year	357.0	353.3	329.3
Funded status at end of year	(82.8)	(47.0)
Post-Retirement Medical Plan
Change in benefit obligation:
Benefit obligation at beginning of year	18.2	22.0
Service cost	0.8	1.1	1.0
Interest cost	0.3	0.3	0.4
Plan amendments	0.0	0.0
Benefit payments	(1.4)	(1.2)
Actuarial gain	(4.0)	(4.0)
Projected benefit obligation at end of year	13.9	18.2	22.0
Change in plan assets:
Fair value of plan assets at beginning of year	0.0	0.0
Actual return on plan assets	0.0	0.0
Benefits paid	(1.4)	(1.2)
Employer contributions	1.4	1.2
Fair value of plan assets at end of year	0.0	0.0	0.0
Reconciliation of funded status:
Fair value of plan assets at end of year	0.0	0.0	0.0
Less benefit obligations at end of year	13.9	18.2	$ 22.0
Funded status at end of year	$ (13.9)	$ (18.2)