Earnings per Share and Stock Repurchase Program (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) $ / shares shares	Dec. 31, 2024 USD ($) $ / shares shares	Dec. 31, 2023 USD ($) $ / shares shares	Jul. 31, 2023 USD ($)
Common Stock
Common Stock conversion ratio, at the option of the holder	1
Net (loss) income
Net income | $	$ 340.8	$ 291.2	$ 262.1
Shares
Shares (in shares)	33,500,000	33,500,000	33,400,000
Per Share Amount
Net income (in dollars per share) | $ / shares	$ 10.17	$ 8.7	$ 7.85
Dilutive securities, principally common stock options
Common stock equivalents (in shares)			100,000
Common stock equivalents (in dollars per share) | $ / shares		$ (0.01)	$ (0.03)
Net (loss) income
Net income | $	$ 340.8	$ 291.2	$ 262.1
Weighted average number of shares:
Shares (in shares)	33,500,000	33,500,000	33,500,000
Securities not included in the computation of diluted EPS
Net income (in dollars per share) | $ / shares	$ 10.17	$ 8.69	$ 7.82
Shares repurchased
Number of shares repurchased	66,519	85,435	91,622
Cost of shares repurchased | $	$ 16.0	$ 17.0	$ 16.0
Class A
Common Stock
Shares of Common Stock reserved for issuance under stock-based compensation plans	1,689,043
Shares repurchased
Value of shares of the entity's Class A common stock authorized to be repurchased | $				$ 150.0
Class B
Common Stock
Shares of Common Stock reserved for conversion	5,916,290
2023 repurchase program | Class A
Shares repurchased
Remaining authorized repurchase amount | $	$ 128.9