RETIREMENT-RELATED BENEFITS - Net Periodic Benefit Cost of Retirement-Related Benefit Plans (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Pension Plans
Cost/(Income) of Pension Plans
Service cost	$ 12.0	$ 16.0	$ 36.0	$ 58.0
Interest cost	$ 9.0	$ 6.0	$ 27.0	$ 10.0
Interest cost - income statement location	Other expense (income)	Other expense (income)	Other expense (income)	Other expense (income)
Expected return on plan assets	$ (10.0)	$ (12.0)	$ (32.0)	$ (25.0)
Expected return on plan assets - income statement location	Other expense (income)	Other expense (income)	Other expense (income)	Other expense (income)
Recognized actuarial losses (gains)	$ 10.0	$ 19.0	$ 30.0	$ 41.0
Recognized actuarial losses - income statement location	Other expense (income)	Other expense (income)	Other expense (income)	Other expense (income)
Curtailments and settlements		$ 2.0		$ 2.0
Curtailments and settlements - income statement location	Other expense (income)	Other expense (income)	Other expense (income)	Other expense (income)
Multi-employer plans/other costs		$ 1.0	$ 4.0	$ 4.0
Net periodic benefit cost	$ 20.0	33.0	64.0	90.0
Non Pension Postretirement Benefit Plans
Cost/(Income) of Pension Plans
Service cost			$ 1.0	2.0
Interest cost		$ 1.0		$ 1.0
Interest cost - income statement location	Other expense (income)	Other expense (income)	Other expense (income)	Other expense (income)
Expected return on plan assets				$ (1.0)
Expected return on plan assets - income statement location	Other expense (income)	Other expense (income)	Other expense (income)	Other expense (income)
Recognized actuarial losses - income statement location	Other expense (income)	Other expense (income)	Other expense (income)	Other expense (income)
Curtailments and settlements - income statement location	Other expense (income)	Other expense (income)	Other expense (income)	Other expense (income)
Net periodic benefit cost		$ 1.0	$ 1.0	$ 2.0