Stockholders' Deficit - Amounts Reclassified from AOCL (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Accumulated other comprehensive income (loss)
Reclassification from AOCL, net of tax	$ 4.4	$ (1.1)
Investment Securities
Accumulated other comprehensive income (loss)
Reclassification from AOCL, Provision for income taxes	(0.2)
Reclassification from AOCL, net of tax	0.4
Investment Securities \| Revenue
Accumulated other comprehensive income (loss)
Reclassification from AOCL, before tax	0.6
Hedging Activities
Accumulated other comprehensive income (loss)
Reclassification from AOCL, Provision for income taxes	(0.1)
Reclassification from AOCL, net of tax	6.3	1.4
Hedging Activities \| Foreign currency contracts \| Revenue
Accumulated other comprehensive income (loss)
Reclassification from AOCL, before tax	6.6	1.4
Hedging Activities \| Interest rate contracts \| Interest Expense
Accumulated other comprehensive income (loss)
Reclassification from AOCL, before tax	(0.2)
Defined benefit plans
Accumulated other comprehensive income (loss)
Reclassification from AOCL, Provision for income taxes	0.7	0.2
Reclassification from AOCL, net of tax	(2.3)	(2.5)
Defined benefit plans \| Other income, net
Accumulated other comprehensive income (loss)
Reclassification from AOCL, before tax	$ (3.0)	$ (2.7)

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