Restructuring - Restructuring Charges By Segment (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 81.6	$ 50.2	$ 65.0
Severance
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	75.8	50.1	65.0
Severance | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	24.7	25.1	5.7
Severance | Eurasia Banking Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	32.1	13.5	37.1
Severance | Americas Banking Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	2.5	1.8	8.9
Severance | Retail Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	16.5	9.7	13.3
Other Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	5.8	0.1	0.0
Other Restructuring | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	1.6	0.0	0.0
Other Restructuring | Eurasia Banking Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	2.0	0.0	0.0
Other Restructuring | Americas Banking Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	0.0	0.1	0.0
Other Restructuring | Retail Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	2.2	$ 0.0	0.0
DN2020 Plan [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges			$ 6.1
DN2020 Plan [Member] | Severance
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	95.8
DN2020 Plan [Member] | Severance | Corporate, Non-Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	15.1
DN2020 Plan [Member] | Severance | Eurasia Banking Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	51.5
DN2020 Plan [Member] | Severance | Americas Banking Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	13.6
DN2020 Plan [Member] | Severance | Retail Segment [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring and Related Cost, Cost Incurred to Date	$ 15.6