Restructuring (Textuals) (Details) - USD ($) $ in Millions	12 Months Ended				36 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2021
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 50.2	$ 65.0	$ 49.4
DN Now Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		50.2	58.9
DN Now Plan [Member] | Minimum
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost		50.0
DN Now Plan [Member] | Maximum
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Expected Cost		70.0
DN2020 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			6.0	47.0
Strategic Alliance Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			0.1	2.4
Severance
Restructuring Cost and Reserve [Line Items]
Restructuring Charges		$ 50.1	$ 65.0	$ 49.4
Subsequent Event [Member] | DN Now Plan [Member]
Restructuring Cost and Reserve [Line Items]
Anticipated Annual Synergies					$ 440.0
Subsequent Event [Member] | Severance | DN Now Plan [Member]
Restructuring Cost and Reserve [Line Items]
Anticipated Annual Synergies	$ 130.0