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Stock-Based Compensation Plans (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	May 21, 2019
Stock-based Compensation Arrangement by Stock-based Payment Award [Line Items]
Number of shares authorized (in shares)					4,236,959
Shares available for issuance (in shares)	3,136,192		3,136,192
Stock-based compensation cost	$ 2.1	$ 2.2	$ 4.1	$ 4.1
Total unrecognized compensation cost related to non-vested share-based compensation arrangements	$ 12.9		$ 12.9
Compensation cost not yet recognized, period for recognition			1 year 9 months 18 days
Performance-Based Restricted Stock Units
Stock-based Compensation Arrangement by Stock-based Payment Award [Line Items]
Granted, number of shares (in shares)			154,363	154,511
Grants in period, weighted average grant date fair value (in dollars per share)			$ 25.48	$ 29.90
2010 LTIP \| Restricted Stock Units
Stock-based Compensation Arrangement by Stock-based Payment Award [Line Items]
Granted, number of shares (in shares)			280,325	223,308
Grants in period, weighted average grant date fair value (in dollars per share)			$ 25.38	$ 29.38