Stock-Based Compensation (Restricted Stock Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) award shares	Dec. 31, 2018 USD ($) award shares	Dec. 31, 2017 USD ($) award shares
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units granted (in shares) | shares	66,000	78,000	77,000
Compensation expense, restricted stock | $	$ 2.5	$ 2.3	$ 2.0
Unrecognized compensation cost | $	$ 2.7
Unrecognized compensation cost, period for recognition (in years)	1 year 8 months 12 days
Fair value of restricted stock that vested | $	$ 2.6	$ 2.3	$ 2.0
Restricted Stock | Independent Board of Directors
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units granted (in shares) | shares	37,166	29,638	30,219
Restricted Stock | Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units granted (in shares) | shares	65,824	78,799	77,072
Vesting period	3 years
Performance-based RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units granted (in shares) | shares	93,000	113,000	100,000
Types of performance-based RSUs | award		2,000	2,000
Targeted number of units outstanding (in shares) | shares	92,649	110,488	94,845
Performance-based RSUs | Key Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Types of performance-based RSUs | award	2
Payout range minimum (as a percent)	0.00%
Payout range maximum (as a percent)	200.00%
Time-vested RSUs | Key Employee
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of restricted stock units granted (in shares) | shares	42,809	4,459	66,181
Vesting period	3 years
RSUs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost, period for recognition (in years)	1 year 1 month 6 days
Estimate of future expense for all types of RSUs outstanding | $	$ 6.5
Total cash paid for vesting and dividend payments | $	6.1
Recognized compensation expense related to RSUs for employees and directors, before capitalization or income tax benefit, if any | $	$ 9.9	$ 4.6	$ 7.0