Employee Share-Based Incentive Compensation Plans - Performance Shares (Details) - USD ($) $ in Millions	1 Months Ended			12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Target Performance Shares Outstanding
Beginning of period (in shares)				34,859	37,031	39,449
Shares paid or expired (in shares)				(13,150)	(13,475)	(13,350)
Grants in period (in shares)				10,670	11,405	10,895
Forfeitures and cancellations (in shares)				37	(102)	37
End of period (in shares)				32,416	34,859	37,031
Accrued Expense
Beginning of period				$ 71.1	$ 69.4	$ 67.5
Shares paid or expired				(48.7)	(44.9)	(40.8)
New grants				0.0	0.0	0.0
Forfeitures and cancellations				0.0	0.0	(0.1)
Expense recognized				50.8	46.6	42.8
End of period				$ 73.2	$ 71.1	$ 69.4
Performance Shares
Accrued Expense
Percentage of target payout - minimum actual	200.00%	188.00%	200.00%