Loans (Schedule of Loans by Product) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Loans And Leases Receivable Disclosure [Line Items]
Total loans	$ 38,530.4	$ 30,998.9	$ 31,247.0
Commercial Loans
Loans And Leases Receivable Disclosure [Line Items]
Total loans	30,696.8	25,019.5
Commercial Loans | Commercial loans
Loans And Leases Receivable Disclosure [Line Items]
Total loans	28,445.3	22,765.1
Commercial Loans | Financing Leases and Leverage Leases
Loans And Leases Receivable Disclosure [Line Items]
Total loans	2,251.5	2,254.4
Consumer Loans
Loans And Leases Receivable Disclosure [Line Items]
Total loans	$ 7,833.6	$ 5,979.4