Special Charges (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Special charges for workforce reductions and advisory costs	$ 0.6	$ 0.8	$ 0.5	$ (2.2)
Termination benefit costs			0.6
Restructuring cost, settled without cash			0.1
Contract Termination [Member]
Special charges for workforce reductions and advisory costs			$ 0.0
Termination benefit costs				$ 2.9

Amount of expenses for special or contractual termination benefits provided to current employees involuntarily terminated under a benefit arrangement associated exit or disposal activities pursuant to an authorized plan. Excludes expenses related to one-time termination benefits, a discontinued operation or an asset retirement obligation.

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