Investment Securities (Investments In Private Equity Funds Subject to Lock-Up Periods) (Details) - Private equity funds $ in Millions	Jun. 30, 2017 USD ($)
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other long-term investments	$ 76.4
1-3 years
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other long-term investments	3.6
3-5 years
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other long-term investments	20.9
5-10 years
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other long-term investments	29.7
Greater than 10 years
Schedule of Trading Securities and Other Trading Assets [Line Items]
Other long-term investments	$ 22.2