Discontinued Operations and Special (Gains) Charges - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Provision for income taxes	$ 7.4	$ 4.7	$ 15.2	$ 13.1
Special charges (settlement)	0.0	$ (0.8)	0.0	$ (0.8)
Discontinued Operations - Disposed of by Sale | NATG
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Vendor settlements	0.8		0.9
Facility costs and professional fees	0.1		0.8
Provision for income taxes	0.2		0.5
Restitution receipts			1.9
Discontinued Operations - Disposed of by Sale | NATG | Maximum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Additional charges (less than)	$ 0.5		$ 0.5