Goodwill and Other Intangibles (Goodwill by Reporting Segment) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
Goodwill [Roll Forward]
Goodwill, Beginning Balance	$ 707.2
Foreign Exchange Rates	(3.2)
Goodwill, Ending Balance	704.0
CORPORATE & INSTITUTIONAL SERVICES
Goodwill [Roll Forward]
Goodwill, Beginning Balance	636.0
Foreign Exchange Rates	(3.2)
Goodwill, Ending Balance	632.8
WEALTH MANAGEMENT
Goodwill [Roll Forward]
Goodwill, Beginning Balance	71.2
Foreign Exchange Rates	0.0
Goodwill, Ending Balance	$ 71.2