Goodwill and Other Assets (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill	$ 1,244.6	$ 1,234.9	$ 1,269.1
Accumulated impairment losses	(470.9)	(470.9)	(470.9)
Beginning balance	764.0	798.2
Transferred to assets held for sale	(8.8)	(11.7)
Divestitures		(4.3)
Currency translation adjustment	18.5	(18.2)
Ending balance	773.7	764.0
Eurasia Banking
Goodwill [Line Items]
Goodwill	580.1	579.2	598.6
Accumulated impairment losses	(291.7)	(291.7)	(291.7)
Beginning balance	287.5	306.9
Transferred to assets held for sale	(6.4)	(11.7)
Divestitures		(0.4)
Currency translation adjustment	7.3	(7.3)
Ending balance	288.4	287.5
Americas Banking
Goodwill [Line Items]
Goodwill	435.0	431.3	437.3
Accumulated impairment losses	(122.0)	(122.0)	(122.0)
Beginning balance	309.3	315.3
Transferred to assets held for sale	(2.4)	0.0
Divestitures		0.0
Currency translation adjustment	6.1	(6.0)
Ending balance	313.0	309.3
Retail
Goodwill [Line Items]
Goodwill	229.5	224.4	233.2
Accumulated impairment losses	(57.2)	(57.2)	$ (57.2)
Beginning balance	167.2	176.0
Transferred to assets held for sale	0.0	0.0
Divestitures		(3.9)
Currency translation adjustment	5.1	(4.9)
Ending balance	$ 172.3	$ 167.2

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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