Other Comprehensive Income (Loss) (Schedule of Tax Effects) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit (expense) for income taxes related to other comprehensive income (loss)	$ 196.3	$ (250.0)	$ (695.3)
Foreign currency translation gains/losses
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit (expense) for income taxes related to other comprehensive income (loss)	81.0	(75.9)	(136.2)
Net unrealized gains/losses on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit (expense) for income taxes related to other comprehensive income (loss)	(3.2)	12.4	4.7
Retirement benefit plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit (expense) for income taxes related to other comprehensive income (loss)	141.5	(95.6)	(532.0)
Net unrealized gains/losses on cash flow hedges
Accumulated Other Comprehensive Income (Loss) [Line Items]
Benefit (expense) for income taxes related to other comprehensive income (loss)	$ (23.0)	$ (90.9)	$ (31.8)