Stock-Based Compensation - Fair Value Assumptions (Details) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) item $ / shares shares	Dec. 31, 2018 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) $ / shares
Fair value assumptions:
Expected term		5 years 3 months 18 days	5 years 3 months 18 days
Additional information
Allocated Share-based Compensation Expense | $	$ 5.9	$ 7.2	$ 6.4
Stock Options
Stock-Based Compensation
Weighted-average fair value per share of options granted (in dollars per share)		$ 13.06	$ 11.43
Fair value assumptions:
Expected dividend yield (as a percent)		0.79%	0.89%
Expected stock price volatility (as a percent)		31.70%	34.50%
Risk-free interest rate (as a percent)		2.66%	2.11%
Other information
Compensation expense yet to be recognized | $	$ 0.1
Weighted-average period over which compensation cost will be recognized	1 year
Total fair value of options vested | $	$ 0.9
Nonvested Options, Shares
Nonvested at beginning of year (in shares) | shares	163
Vested (in shares) | shares	(82)
Nonvested at end of year (in shares) | shares	81	163
Nonvested Options, Weighted-Average Grant Date Fair Value
Nonvested at beginning of year (in dollars per share)	$ 11.99
Granted (in dollars per share)		$ 13.06	$ 11.43
Vested (in dollars per share)	11.46
Nonvested at end of year (in dollars per share)	$ 12.53	$ 11.99
Additional information
Vesting period	3 years
Restricted Stock and Restricted Stock Units
Other information
Compensation expense yet to be recognized | $	$ 0.9
Weighted-average period over which compensation cost will be recognized	1 year 10 months 24 days
Shares
Unvested at beginning of year (in shares) | shares	78
Granted (in shares) | shares	87
Vested (in shares) | shares	(69)
Forfeited (in shares) | shares	(5)
Unvested at end of year (in shares) | shares	91	78
Weighted Average Grant Date Fair Value
Unvested at beginning of year (in dollars per share)	$ 38.17
Granted (in dollars per share)	51.02	$ 44.02	35.69
Vested (in dollars per share)	41.58
Forfeited (in dollars per share)	44.01
Unvested at end of year (in dollars per share)	$ 47.58	38.17
Additional information
Fair value of shares vested | $	$ 2.9
Weighted-average fair value (in dollars per share)	$ 51.02	$ 44.02	$ 35.69
Aggregate intrinsic value of restricted stock vested | $	$ 3.5	$ 3.3	$ 3.2
Performance Stock Units
Other information
Compensation expense yet to be recognized | $	$ 0.4
Weighted-average period over which compensation cost will be recognized	1 year 4 months 24 days
Additional information
Vesting period	3 years
Types of performance units | item	2
Percentage of units measured on stock price relative to peer group	50.00%
Percentage of units measured on stock price based on pre determined EPS	50.00%
Period for which shareholder return is compared with peer group for units determined by EPS performance	3 years
Calculated fair market value | $	$ 5.0
Value of PSUs granted | $	1.9
Allocated Share-based Compensation Expense | $	$ 1.9	$ 2.9	$ 2.6
Performance Stock Units | Minimum
Additional information
Performance measures for dollar denominated award granted	0
Performance Stock Units | Maximum
Additional information
Performance measures for dollar denominated award granted	2.0