Investment Securities (Investments In Private Equity Funds Subject to Lock-Up Periods) (Details) - Private equity security $ in Millions	Sep. 30, 2019 USD ($)
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	$ 90.6
1-3 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	5.4
3-5 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	16.5
5-10 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	56.3
Greater than 10 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	$ 12.4