Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance			$ (164.9)	$ (106.7)
Balance, January 1, 2018	$ (172.8)	$ (110.4)	(172.8)	(110.4)
Other comprehensive income (loss), before reclassifications, net of tax			9.1	30.8
Amounts reclassified from accumulated other comprehensive income, net of tax			(17.0)	(34.5)
Other comprehensive income (loss), net of tax	(0.8)	4.8	(7.9)	(3.7)
Accumulated other comprehensive income (loss), net of tax ending balance	(172.8)	(110.4)	(172.8)	(110.4)
Other comprehensive income (loss), net of tax	(0.8)	4.8	(7.9)	(3.7)
Gains (losses) on securities available for sale
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance			(15.7)	(2.2)
Balance, January 1, 2018	(14.5)	(20.2)	(14.5)	(20.2)
Other comprehensive income (loss), before reclassifications, net of tax			(0.2)	(19.1)
Amounts reclassified from accumulated other comprehensive income, net of tax			1.4	1.1
Other comprehensive income (loss), net of tax			1.2	(18.0)
Accumulated other comprehensive income (loss), net of tax ending balance	(14.5)	(20.2)	(14.5)	(20.2)
Gains (losses) on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance			15.1	53.8
Balance, January 1, 2018	(13.4)	126.9	(13.4)	126.9
Other comprehensive income (loss), before reclassifications, net of tax			(10.1)	129.5
Amounts reclassified from accumulated other comprehensive income, net of tax			(18.4)	(56.4)
Other comprehensive income (loss), net of tax			(28.5)	73.1
Accumulated other comprehensive income (loss), net of tax ending balance	(13.4)	126.9	(13.4)	126.9
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
Balance, January 1, 2018		0.0		0.0
Other comprehensive income (loss), before reclassifications, net of tax				12.6
Amounts reclassified from accumulated other comprehensive income, net of tax				(38.1)
Other comprehensive income (loss), net of tax				(25.5)
Accumulated other comprehensive income (loss), net of tax ending balance		0.0		0.0
Unfunded status of postretirement benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance			(1.1)	(44.8)
Balance, January 1, 2018	(0.4)	(42.1)	(0.4)	(42.1)
Other comprehensive income (loss), before reclassifications, net of tax			0.7	2.7
Amounts reclassified from accumulated other comprehensive income, net of tax			0.0	0.0
Other comprehensive income (loss), net of tax			0.7	2.7
Accumulated other comprehensive income (loss), net of tax ending balance	(0.4)	(42.1)	(0.4)	(42.1)
Currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated other comprehensive income (loss), net of tax beginning balance			(163.2)	(139.0)
Balance, January 1, 2018	(144.5)	(175.0)	(144.5)	(175.0)
Other comprehensive income (loss), before reclassifications, net of tax			18.7	(94.9)
Amounts reclassified from accumulated other comprehensive income, net of tax			0.0	58.9
Other comprehensive income (loss), net of tax			18.7	(36.0)
Accumulated other comprehensive income (loss), net of tax ending balance	$ (144.5)	$ (175.0)	$ (144.5)	$ (175.0)