Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance	$ (106.7)	$ (299.0)
Balance, January 1, 2018	(115.2)	(174.3)
Other comprehensive income (loss), before reclassifications, net of tax	8.4	103.3
Amounts reclassified from accumulated other comprehensive income, net of tax	(16.9)	21.4
Other comprehensive income (loss), net of tax	(8.5)	125.4
Accumulated other comprehensive income (loss), net of tax ending balance	(115.2)	(174.3)
Other comprehensive income (loss), net of tax	(8.5)	124.7
Unrealized gains (losses) on securities available for sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance	(2.2)	1.4
Balance, January 1, 2018	(11.9)	0.6
Other comprehensive income (loss), before reclassifications, net of tax	(10.2)	(1.2)
Amounts reclassified from accumulated other comprehensive income, net of tax	0.5	0.4
Other comprehensive income (loss), net of tax	(9.7)	(0.8)
Accumulated other comprehensive income (loss), net of tax ending balance	(11.9)	0.6
Unrealized gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance	53.8	(179.0)
Balance, January 1, 2018	69.7	(29.4)
Other comprehensive income (loss), before reclassifications, net of tax	34.4	128.6
Amounts reclassified from accumulated other comprehensive income, net of tax	(18.5)	21.0
Other comprehensive income (loss), net of tax	15.9	149.6
Accumulated other comprehensive income (loss), net of tax ending balance	69.7	(29.4)
Gains (losses) on net investment hedge
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance	25.5	(8.5)
Balance, January 1, 2018	31.7	13.9
Other comprehensive income (loss), before reclassifications, net of tax	5.1	22.4
Amounts reclassified from accumulated other comprehensive income, net of tax	1.1	0.0
Other comprehensive income (loss), net of tax	6.2	22.4
Accumulated other comprehensive income (loss), net of tax ending balance	31.7	13.9
Unfunded status of postretirement benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance	(44.8)	(66.3)
Balance, January 1, 2018	(43.9)	(64.3)
Other comprehensive income (loss), before reclassifications, net of tax	0.9	2.0
Amounts reclassified from accumulated other comprehensive income, net of tax	0.0	0.0
Other comprehensive income (loss), net of tax	0.9	2.0
Accumulated other comprehensive income (loss), net of tax ending balance	(43.9)	(64.3)
Currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance	(139.0)	(46.6)
Balance, January 1, 2018	(160.8)	(95.1)
Other comprehensive income (loss), before reclassifications, net of tax	(21.8)	(48.5)
Amounts reclassified from accumulated other comprehensive income, net of tax	0.0	0.0
Other comprehensive income (loss), net of tax	(21.8)	(48.5)
Accumulated other comprehensive income (loss), net of tax ending balance	$ (160.8)	$ (95.1)