Investment Securities (Investments In Private Equity Funds Subject to Lock-Up Periods) (Details) - Private equity security $ in Millions	Jun. 30, 2020 USD ($)
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	$ 105.9
1-3 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	4.7
3-5 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	40.4
5-10 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	56.7
Greater than 10 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	$ 4.1