Segment Information - (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021		Jun. 30, 2020
Summary of Segment Information
Total revenue	$ 943.5	$ 890.5	$ 1,887.4		$ 1,801.2
Segment gross profit	251.9	247.6	525.1		474.4
Segment selling and administrative expense	204.8	181.6	408.2		403.7
Segment research, development and engineering expense	35.6	30.7	69.7		63.2
Operating income (loss) / Segment operating profit	(12.9)	(20.5)	(49.1)		5.5
Restructuring and DN Now transformation expenses	(17.1)	(11.5)	(23.1)		(21.5)
Net non-routine expense			(19.9)
Other income (expense)	(53.9)	(47.0)	(95.9)		(94.4)
Income (loss) from continuing operations before taxes	(41.0)	(26.5)	(46.8)		(99.9)
Eurasia Banking
Summary of Segment Information
Total revenue	326.0	337.7	653.8		648.2
Americas Banking
Summary of Segment Information
Total revenue	312.5	331.4	624.2		676.1
Retail
Summary of Segment Information
Total revenue	305.0	221.4	609.4		476.9
Operating Segments [Member]
Summary of Segment Information
Intersegment revenue	45.6	36.0	76.3		58.7
Operating income (loss) / Segment operating profit	(81.3)	(103.7)	(173.6)		(184.1)
Operating Segments [Member] | Eurasia Banking
Summary of Segment Information
Total revenue	326.0	337.7	653.8		648.2
Intersegment revenue	43.9	32.4	72.4		53.8
Operating income (loss) / Segment operating profit	(26.2)	(37.1)	(51.2)		(59.9)
Operating Segments [Member] | Americas Banking
Summary of Segment Information
Total revenue	312.5	331.4	624.2		676.1
Intersegment revenue	1.7	3.6	3.9		4.9
Operating income (loss) / Segment operating profit	(26.9)	(56.4)	(67.1)		(102.9)
Operating Segments [Member] | Retail
Summary of Segment Information
Total revenue	305.0	221.4	609.4		476.9
Operating income (loss) / Segment operating profit	(28.2)	(10.2)	(55.3)		(21.3)
Corporate and Reconciling Items [Member]
Summary of Segment Information
Reconciliation Of Operating Profit Loss From Segments To Consolidated, Amount	(68.4)	(83.2)	(124.5)		(189.6)
Corporate
Summary of Segment Information
Operating income (loss) / Segment operating profit	(18.2)	(5.5)	31.5	[1]	22.9	[1]
Segment Reconciling Items [Member]
Summary of Segment Information
Restructuring and DN Now transformation expenses	(30.4)	(26.8)	(53.5)		(68.4)
Net non-routine expense	$ (19.8)	$ (50.9)	$ (39.5)		$ (98.3)

[1] Corporate charges not allocated to segments include headquarter-based costs associated with human resources, compensation and benefits, finance and accounting, global development/engineering, global strategy/mergers and acquisitions, global IT, tax, treasury and legal.