Stock-Based Compensation, Stock Award and Incentive Plan and Stock Options (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Employee service share-based compensation, aggregate disclosures [Abstract]
Increase in number of shares available for issuance (in shares)	1,300,000
Term of stock options granted under Plan	10 years
Share based compensation costs	$ 10.2	$ 8.1	$ 6.2
Minimum [Member]
Employee service share-based compensation, aggregate disclosures [Abstract]
Vesting period	1 year
Maximum [Member]
Employee service share-based compensation, aggregate disclosures [Abstract]
Percentage of shares not subject to minimum vesting requirement	5.00%
Stock Options [Member]
Employee service share-based compensation, aggregate disclosures [Abstract]
Vesting period	3 years
Share based compensation costs	$ 4.6	4.8	4.2
Tax benefit of share-based compensation	$ 1.2	$ 1.3	$ 1.1
Forfeiture rate assumed	8.45%	8.85%	8.20%
Weighted average grant date fair value for stock options granted (in dollars per share)	$ 18.99	$ 18.86	$ 25.79
Weighted average grant date fair value for stock options vested (in dollars per share)	$ 23.85	$ 22.46	$ 21.33
Total intrinsic value of stock options exercised	$ 2.3	$ 2.2	$ 3.3
Weighted Average Assumptions [Abstract]
Expected life	6 years 8 months 12 days	6 years 7 months 6 days	6 years 2 months 12 days
Interest rate	1.67%	2.62%	2.50%
Volatility	30.34%	30.26%	30.33%
Expected dividend yield	0.35%	0.37%	0.26%
Stock Options [Roll Forward]
Balance, beginning of year (in shares)	1,227,620
Granted (in shares)	286,078
Exercised (in shares)	(93,099)
Canceled (in shares)	(57,233)
Balance, end of year (in shares)	1,363,366	1,227,620
Exercisable, end of year (in shares)	876,206
Weighted Average Exercise Price Per Share [Abstract]
Balance, beginning of year (in dollars per share)	$ 55.83
Granted (in dollars per share)	57.67
Exercised (in dollars per share)	35.11
Canceled (in dollars per share)	63.92
Balance, end of year (in dollars per share)	57.29	$ 55.83
Exercisable, end of year (in dollars per share)	$ 56.55
Weighted Average Remaining Contractual Life [Abstract]
Outstanding options, end of year	6 years 1 month 24 days
Exercisable options, end of year	4 years 9 months 29 days
Aggregate Intrinsic Value [Abstract]
Outstanding options, end of year	$ 11.4
Exercisable options, end of year	$ 8.9
Additional Information [Abstract]
Closing stock price on last business day of the period (in dollars per share)	$ 62.12
Weighted average intrinsic value of options exercised (in dollars per share)	$ 24.41	$ 27.21	$ 33.10
Unrecognized stock-based compensation expense	$ 4.7
Weighted average period over which unrecognized stock-based compensation expense is expected to be recognized	3 years
Nonvested Stock Options [Member]
Stock Options [Roll Forward]
Balance, beginning of year (in shares)	438,773
Granted (in shares)	286,078
Vested (in shares)	(199,723)
Canceled (in shares)	(37,968)
Balance, end of year (in shares)	487,160	438,773
Weighted Average Exercise Price Per Share [Abstract]
Balance, beginning of year (in dollars per share)	$ 63.15
Granted (in dollars per share)	57.67
Vested (in dollars per share)	66.94
Canceled (in dollars per share)	60.15
Balance, end of year (in dollars per share)	$ 58.61	$ 63.15