Common Equity - Restricted Shares (Details) - Restricted stock - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Restricted Stock Activity
Outstanding, shares, beginning of period	105,242	100,398
Granted, shares		108,484
Released, shares		(99,941)
Forfeited, shares		(3,699)
Outstanding, shares, end of period		105,242	100,398
Restricted Stock Weighted-Average Grant Date Fair Value
Outstanding, weighted-average grant date fair value, beginning of period	$ 87.61	$ 93.95
Granted, weighted-average grant date fair value		84.96
Released, weighted-average grant date fair value		91.07
Forfeited, weighted-average grant date fair value		88.56
Outstanding, weighted-average grant date fair value, end of period		$ 87.61	$ 93.95
Restricted Stock - Additional Disclosures
Intrinsic value of released restricted shares		$ 8.6	$ 5.8	$ 7.5
Tax benefit from released restricted shares		2.4	$ 1.6	$ 2.1
Compensation cost not yet recognized		$ 4.2
Weighted-average period over which unrecognized compensation cost is expected to be recognized		1 year 9 months 18 days
Subsequent event
Restricted Stock Activity
Granted, shares	79,170
Restricted Stock Weighted-Average Grant Date Fair Value
Granted, weighted-average grant date fair value	$ 94.55