Restructuring (Textuals) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended	36 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2021
Unusual or Infrequent Item [Line Items]
Restructuring charges	$ 7.4	$ 2.2	$ 11.2	$ 6.1
DN Now Plan [Member] | Minimum [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Expected Cost	125.0		125.0
DN Now Plan [Member] | Maximum [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Expected Cost	175.0		175.0
DN Now [Member]
Unusual or Infrequent Item [Line Items]
Restructuring charges	7.4		11.2
DN2020 Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring charges		2.2		6.0
Strategic Alliance Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring charges				0.1
Segment Reconciling Items [Member]
Unusual or Infrequent Item [Line Items]
Restructuring charges	25.4	2.2	40.5	6.1
Subsequent Event [Member] | DN Now Plan [Member]
Unusual or Infrequent Item [Line Items]
Anticipated Annual Synergies					$ 175.0	$ 400.0
Severance
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	174.1		174.1
Restructuring charges	7.3	2.2	11.1	6.1
Severance | DN Now [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	70.0		70.0
Severance | DN2020 Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	95.8		95.8
Severance | Strategic Alliance Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	8.2		8.2
Severance | Eurasia Banking
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	95.8		95.8
Restructuring charges	1.3	1.2	2.8	3.7
Severance | Eurasia Banking | DN Now [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	36.1		36.1
Severance | Eurasia Banking | DN2020 Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	51.5		51.5
Severance | Eurasia Banking | Strategic Alliance Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	8.2		8.2
Severance | Americas Banking
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	22.9		22.9
Restructuring charges	0.2	0.2	0.6	0.3
Severance | Americas Banking | DN Now [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	9.2		9.2
Severance | Americas Banking | DN2020 Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	13.6		13.6
Severance | Americas Banking | Strategic Alliance Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	0.0		0.0
Severance | Retail
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	31.7		31.7
Restructuring charges	2.8	0.3	3.6	0.8
Severance | Retail | DN Now [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	16.1		16.1
Severance | Retail | DN2020 Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	15.6		15.6
Severance | Retail | Strategic Alliance Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	0.0		0.0
Severance | Corporate
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	23.7		23.7
Restructuring charges	3.0	0.5	4.1	1.3
Severance | Corporate | DN Now [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	8.6		8.6
Severance | Corporate | DN2020 Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	15.1		15.1
Severance | Corporate | Strategic Alliance Plan [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	0.0		0.0
Other Restructuring [Member]
Unusual or Infrequent Item [Line Items]
Restructuring charges	0.1	0.0	0.1	0.0
Other Restructuring [Member] | DN Now [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	0.1		0.1
Other Restructuring [Member] | Eurasia Banking | DN Now [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	0.0		0.0
Other Restructuring [Member] | Americas Banking
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	0.1		0.1
Restructuring charges	0.1	$ 0.0	0.1	$ 0.0
Other Restructuring [Member] | Retail | DN Now [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	0.0		0.0
Other Restructuring [Member] | Corporate | DN Now [Member]
Unusual or Infrequent Item [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	$ 0.0		$ 0.0