Accumulated Other Comprehensive Loss (Summary of changes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance: Accumulated other comprehensive loss	$ (8.7)	$ (7.2)
Other comprehensive loss before reclassifications	(3.3)	(1.6)
Amounts reclassified from accumulated other comprehensive loss	1.4	0.1
Total other comprehensive income (loss)	(1.9)	(1.5)	$ 1.1
Ending balance: Accumulated other comprehensive income (loss)	(10.6)	(8.7)	(7.2)
Derivatives
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance: Accumulated other comprehensive loss	0.0	0.0
Other comprehensive loss before reclassifications	0.2	0.0
Amounts reclassified from accumulated other comprehensive loss	0.0	0.0
Total other comprehensive income (loss)	0.2	0.0
Ending balance: Accumulated other comprehensive income (loss)	0.2	0.0	0.0
Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance: Accumulated other comprehensive loss	(7.5)	(6.0)
Other comprehensive loss before reclassifications	(3.5)	(1.6)
Amounts reclassified from accumulated other comprehensive loss	0.2	0.1
Total other comprehensive income (loss)	(3.3)	(1.5)
Ending balance: Accumulated other comprehensive income (loss)	(10.8)	(7.5)	(6.0)
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance: Accumulated other comprehensive loss	(1.2)	(1.2)
Other comprehensive loss before reclassifications	0.0	0.0
Amounts reclassified from accumulated other comprehensive loss	1.2	0.0
Total other comprehensive income (loss)	1.2	0.0
Ending balance: Accumulated other comprehensive income (loss)	$ 0.0	$ (1.2)	$ (1.2)