Other Assets (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Proportional amortization as a component of income tax expense	$ 10.0	$ 7.0	$ 3.6
Affordable housing tax credits and other tax benefits, amount	12.3	8.4	$ 4.3
Capital commitments relating to investments	$ 84.5	$ 67.0