Earnings per Share and Stock Repurchase Program (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($) $ / shares shares	Dec. 31, 2020 USD ($) $ / shares shares	Dec. 31, 2019 USD ($) $ / shares shares	Feb. 06, 2019 USD ($)
Common Stock
Common Stock conversion ratio, at the option of the holder	1
Net (loss) income
Net income | $	$ 165.7	$ 114.3	$ 131.5
Shares
Shares (in shares) | shares	33,800,000	33,900,000	34,100,000
Per Share Amount
Net income (in dollars per share) | $ / shares	$ 4.90	$ 3.37	$ 3.86
Dilutive securities, principally common stock options
Common stock equivalents (in shares) | shares		100,000	100,000
Common stock equivalents (in dollars per share) | $ / shares	$ (0.02)	$ (0.01)	$ (0.01)
Net (loss) income
Net income | $	$ 165.7	$ 114.3	$ 131.5
Weighted average number of shares:
Shares (in shares) | shares	33,900,000	34,000,000.0	34,200,000
Securities not included in the computation of diluted EPS
Net income (in dollars per share) | $ / shares	$ 4.88	$ 3.36	$ 3.85
Shares repurchased
Number of shares repurchased | shares	109,998	331,531
Stock Repurchased During Period, Value | $	$ 16.0	$ 28.9
Cost of shares repurchased | $	$ 16.0	$ 28.9	$ 19.5
Class A
Common Stock
Common Stock, votes per share (Number of votes)	1	1
Shares of Common Stock reserved for issuance under stock-based compensation plans | shares	2,157,082
Class B
Common Stock
Common Stock, votes per share (Number of votes)	10	10
Shares of Common Stock reserved for conversion | shares	6,024,290
February 6, 2019 | Class A
Shares repurchased
Value of shares of the entity's Class A common stock authorized to be repurchased | $				$ 150.0
Remaining authorized repurchase amount | $	$ 97.4