Goodwill and Other Assets (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Line Items]
Goodwill, Transfers				$ (47.0)
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	$ 128.0			128.0
Goodwill	1,335.3			1,335.3	$ 1,407.8	$ 1,289.0
Accumulated impairment losses	(508.2)			(508.2)	(290.7)	(290.7)
Beginning balance				1,117.1	998.3
Goodwill acquired					5.6
Impairment loss	0.0	$ 0.0	$ (83.1)	(217.5)
Goodwill, Purchase Accounting Adjustments					(2.9)
Currency translation adjustment				(25.5)	116.1
Ending balance	827.1			827.1	1,117.1	998.3
Impairment of assets		134.4	83.1	217.5	3.1	9.8
Finite-Lived Intangible Assets, Amortization Expense, Year Two	108.8			108.8
Finite-Lived Intangible Assets, Amortization Expense, Year Three	96.2			96.2
Finite-Lived Intangible Assets, Amortization Expense, Year Four	92.0			92.0
Finite-Lived Intangible Assets, Amortization Expense, Year Five	88.6			88.6
Finite-Lived Intangible Assets, Net	513.6			513.6
Eurasia Banking Segment [Member]
Goodwill [Line Items]
Goodwill, Transfers				(0.8)
Goodwill	628.6			628.6	639.4	592.2
Accumulated impairment losses	(321.7)			(321.7)	(168.7)	(168.7)
Beginning balance				470.7	423.5
Goodwill acquired					2.2
Impairment loss				(153.0)
Goodwill, Purchase Accounting Adjustments					(1.2)
Currency translation adjustment				(10.0)	46.2
Ending balance	306.9			306.9	470.7	423.5
Retail Segment [Member]
Goodwill [Line Items]
Goodwill, Transfers				(45.9)
Goodwill	252.4			252.4	305.5	273.0
Accumulated impairment losses	(64.5)			(64.5)	0.0	0.0
Beginning balance				305.5	273.0
Goodwill acquired					1.6
Impairment loss				(64.5)
Goodwill, Purchase Accounting Adjustments					(0.7)
Currency translation adjustment				(7.2)	31.6
Ending balance	187.9			187.9	305.5	273.0
Americas Banking Segment [Member]
Goodwill [Line Items]
Goodwill, Transfers				(0.3)
Goodwill	454.3			454.3	462.9	423.8
Accumulated impairment losses	(122.0)			(122.0)	(122.0)	(122.0)
Beginning balance				340.9	301.8
Goodwill acquired					1.8
Impairment loss				0.0
Goodwill, Purchase Accounting Adjustments					(1.0)
Currency translation adjustment				(8.3)	38.3
Ending balance	$ 332.3			$ 332.3	$ 340.9	$ 301.8
Goodwill reallocation [Member] | Previously Reported [Member]
Goodwill [Line Items]
Impairment loss		(109.3)	$ (90.0)
Goodwill reallocation [Member] | Restatement Adjustment [Member]
Goodwill [Line Items]
Impairment loss		$ 0.0