Stock-Based Compensation (Narrative) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 5.8	$ 3.9	$ 14.4	$ 11.4
Basic earnings per share	$ 1.49	$ 0.88	$ 3.43	$ 1.96
Diluted earnings per share	$ 1.48	$ 0.87	$ 3.41	$ 1.95
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted stock granted	0	0	400	600
Grant date fair value			$ 30.43	$ 23.85
Awards vesting period			3 years	3 years
Performance Share Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted	0	0	300	300
Grant date fair value			$ 26.38	$ 22.01
Awards vesting period			3 years	3 years
Shares increased	30
Cumulative catch-up adjustment	$ 0.6		$ 0.6
Cumulative catch-up adjustment, net of tax	$ 0.4		$ 0.4
Basic earnings per share	$ 0.02		$ 0.02
Diluted earnings per share	$ 0.01		$ 0.01
Performance Share Units [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance target range			0.00%	0.00%
Performance Share Units [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance target range			250.00%	250.00%

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