Stock-Based Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024	Dec. 31, 2024	Jan. 01, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock available under stock option plan (in shares)	5,350,333		5,350,333
Vesting period			3 years
Options, outstanding, number (in shares)	114,943		114,943
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price	$ 48.63		$ 48.63
Options, grants in period, gross (in shares)			0
Plan 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares authorized to issue under share based compensation plans (in shares)						12,500,000
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Share-based compensation arrangement age requirement to vest over original vesting period			55 years
Time in service requirement to vest over original vesting period			10 years
Nonvested awards, compensation cost not yet recognized	$ 39.8		$ 39.8		$ 19.2
Nonvested awards, compensation cost not yet recognized, period for recognition			2 years
Equity instruments other than options, vested in period, fair value	2.0	$ 2.3	$ 25.6	$ 28.0
Allocated share-based compensation expense, net of tax	10.1	8.7	18.8	17.4
Allocated share-based compensation expense	$ 7.8	$ 6.8	$ 14.5	$ 13.5
Equity instruments other than options, nonvested, number (in shares)	1,626,786		1,626,786		1,666,683
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period			3 years
Nonvested awards, compensation cost not yet recognized, period for recognition			36 months
Equity instruments other than options, nonvested, number (in shares)	519,000		519,000
Total shareholder return performance measure, as a percentage	15.00%		15.00%
Estimated vesting of shares based on performance shares (in shares)	583,000		583,000
Minimum | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, vested and expected to vest, exercisable, number (in shares)	0		0
Maximum | Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Options, vested and expected to vest, exercisable, number (in shares)	1,193,000		1,193,000
Maximum | Performance Shares | Issue Date 2022 And 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting rights, percentage			230.00%