Common Equity - Stock Options (Details) - Stock options - USD ($) $ / shares in Units, $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Options Activity
Outstanding, shares, beginning balance	2,909,939	3,111,907
Granted, shares		437,269	530,612	554,594
Exercised, shares		(622,459)
Forfeited, shares		(16,778)
Outstanding, shares, ending balance		2,909,939	3,111,907
Options - Weighted Average Exercise Price
Outstanding, Weighted-Average Exercise Price, Beginning	$ 77.03	$ 69.84
Granted, Weighted-Average Exercise Price		96.04
Exercised, Weighted-Average Exercise Price		54.05
Forfeited, Weighted-Average Exercise Price		92.16
Outstanding, Weighted-Average Exercise Price, Ending		$ 77.03	$ 69.84
Options - Additional Disclosures
Outstanding, Weighted-Average Remaining Contractual Life (Years)		6 years 2 months 12 days
Outstanding, Aggregate Intrinsic Value		$ 49.7
Exercisable, shares		1,807,644
Exercisable, Weighted-Average Exercise Price (in dollars per share)		$ 67.40
Exercisable, Weighted-Average Remaining Contractual Life (Years)		5 years
Exercisable, Aggregate Intrinsic Value		$ 47.8
Intrinsic value of options exercised		29.2	$ 12.9	$ 47.1
Tax benefit from option exercises		8.0	$ 3.5	$ 12.9
Compensation cost not yet recognized		$ 2.3
Weighted-average period over which unrecognized compensation cost is expected to be recognized		1 year 6 months
Estimated weighted-average fair value per stock option (in dollars per share)		$ 14.71	$ 13.20	$ 10.94
Subsequent event
Options Activity
Granted, shares	257,780
Options - Weighted Average Exercise Price
Granted, Weighted-Average Exercise Price	$ 93.69
Options - Additional Disclosures
Estimated weighted-average fair value per stock option (in dollars per share)	$ 19.58