Stock-Based Compensation Plans (Information Regarding Restricted Shares) (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
General vesting period (years)	3 years
Unearned compensation costs	$ 24.5	$ 19.2
Recognition of unearned compensation, (years)	1 year
Fair value of Restricted Shares vested	$ 26.6	28.7	$ 24.2
Stock-based compensation expense	38.3	30.5	27.8
Related income tax benefit	(8.8)	(6.9)	(6.3)
Net stock-based compensation expense	$ 29.5	$ 23.6	$ 21.5
Shares
Outstanding — beginning of year (in shares)	1,666,683
Granted (in shares)	859,246
Vested (in shares)	(707,304)
Canceled (in shares)	(112,598)
Outstanding — ending of year (in shares)	1,706,027	1,666,683
Weighted Average Grant-Date Fair Value
Outstanding — beginning of year (in dollars per share)	$ 39.18
Granted (in dollars per share)	57.97
Vested (in dollars per share)	37.57
Canceled (in dollars per share)	50.21
Outstanding — ending of year (in dollars per share)	$ 48.59	$ 39.18
Restricted Stock | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
General expiration period, from date of grant or time of termination (years)	1 year
General vesting period (years)	1 year
Restricted Stock | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
General expiration period, from date of grant or time of termination (years)	3 years
General vesting period (years)	3 years
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
General vesting period (years)	36 months
Shares
Outstanding — ending of year (in shares)	502,000
Weighted Average Grant-Date Fair Value
Estimated vesting of shares based on performance shares	822,000
Performance Shares | Minimum
Weighted Average Grant-Date Fair Value
Estimated vesting of shares based on performance shares	0
Performance Shares | Maximum
Weighted Average Grant-Date Fair Value
Estimated vesting of shares based on performance shares	1,154,000