Stockholders' Equity/(Deficit) - Amounts Reclassified from AOCL (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Investment Securities
Accumulated other comprehensive income (loss)
Reclassification from AOCL, net of tax	$ 0.5	$ 0.5	$ (0.3)
Hedging Activities
Accumulated other comprehensive income (loss)
Reclassification from AOCL, net of tax	0.7	14.1	(16.3)
Defined benefit plans
Accumulated other comprehensive income (loss)
Reclassification from AOCL, net of tax	(9.4)	(8.4)	(9.1)
Reclassification out of Accumulated Other Comprehensive Income (Loss)
Accumulated other comprehensive income (loss)
Reclassification from AOCL, net of tax	(8.2)	6.2	(25.7)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Investment Securities
Accumulated other comprehensive income (loss)
Reclassification from AOCL, Provision for income taxes	(0.1)	(0.1)	0.1
Reclassification from AOCL, net of tax	0.5	0.5	(0.3)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Investment Securities | Revenue
Accumulated other comprehensive income (loss)
Reclassification from AOCL, before tax	0.6	0.6	(0.4)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Hedging Activities
Accumulated other comprehensive income (loss)
Reclassification from AOCL, Provision for income taxes	0.1	(0.1)	0.7
Reclassification from AOCL, net of tax	0.7	14.1	(16.3)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Hedging Activities | Foreign currency contracts | Revenue
Accumulated other comprehensive income (loss)
Reclassification from AOCL, before tax	1.2	14.2	(14.9)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Hedging Activities | Interest rate contracts | Interest Expense
Accumulated other comprehensive income (loss)
Reclassification from AOCL, before tax	(0.6)		(2.1)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Defined benefit plans
Accumulated other comprehensive income (loss)
Reclassification from AOCL, Provision for income taxes	2.7	2.4	2.6
Reclassification from AOCL, net of tax	(9.4)	(8.4)	(9.1)
Reclassification out of Accumulated Other Comprehensive Income (Loss) | Defined benefit plans | Other income, net
Accumulated other comprehensive income (loss)
Reclassification from AOCL, before tax	$ (12.1)	$ (10.8)	$ (11.7)