Investment Securities (Investments In Private Equity Funds Subject to Lock-Up Periods) (Details) - Private equity security $ in Millions	Jun. 30, 2019 USD ($)
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	$ 111.3
1-3 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	4.2
3-5 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	0.0
5-10 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	81.4
Greater than 10 years
Debt and Equity Securities, FV-NI [Line Items]
Fair Value	$ 25.7