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Investment Securities (Restrictions on Redemption Frequency and Advance Notice Requirements) (Details) - Hedge funds $ in Millions | Jun. 30, 2017 USD ($)
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Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | $ 72.1
30-59 days notice |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 53.8
60-89 days notice |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 18.3
Monthly |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 0.0
Monthly | 30-59 days notice |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 0.0
Monthly | 60-89 days notice |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 0.0
Quarterly |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 0.0
Quarterly | 30-59 days notice |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 0.0
Quarterly | 60-89 days notice |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 0.0
Semi-annual |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 72.1
Semi-annual | 30-59 days notice |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 53.8
Semi-annual | 60-89 days notice |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 18.3
Annual |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 0.0
Annual | 30-59 days notice |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | 0.0
Annual | 60-89 days notice |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Other long-term investments | $ 0.0
September 2018 |
Schedule of Trading Securities and Other Trading Assets [Line Items] |
Number of Investments | 1
Other long-term investments | $ 53.8

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