Investment Securities (Restrictions on Redemption Frequency and Advance Notice Requirements) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012
Investment securities
Distributions from Inactive Hedge Funds	$ 3.3
Hedge funds
Investment securities
Other long-term investments	124.3
Monthly | Hedge funds
Investment securities
Other long-term investments	6.8
Quarterly | Hedge funds
Investment securities
Other long-term investments	85.7
Semi-annual | Hedge funds
Investment securities
Other long-term investments	20.6
Annual | Hedge funds
Investment securities
Other long-term investments	11.2
90-119 days notice | Hedge funds
Investment securities
Other long-term investments	28.4
90-119 days notice | Monthly | Hedge funds
Investment securities
Other long-term investments	0
90-119 days notice | Quarterly | Hedge funds
Investment securities
Other long-term investments	19.9
90-119 days notice | Semi-annual | Hedge funds
Investment securities
Other long-term investments	0
90-119 days notice | Annual | Hedge funds
Investment securities
Other long-term investments	8.5
30-59 days notice | Hedge funds
Investment securities
Other long-term investments	29.4
30-59 days notice | Monthly | Hedge funds
Investment securities
Other long-term investments	0
30-59 days notice | Quarterly | Hedge funds
Investment securities
Other long-term investments	27.1
30-59 days notice | Semi-annual | Hedge funds
Investment securities
Other long-term investments	0
30-59 days notice | Annual | Hedge funds
Investment securities
Other long-term investments	2.3
60-89 days notice | Hedge funds
Investment securities
Other long-term investments	49.9
60-89 days notice | Monthly | Hedge funds
Investment securities
Other long-term investments	0
60-89 days notice | Quarterly | Hedge funds
Investment securities
Other long-term investments	29.3
60-89 days notice | Semi-annual | Hedge funds
Investment securities
Other long-term investments	20.6
60-89 days notice | Annual | Hedge funds
Investment securities
Other long-term investments	0
120+ days notice | Hedge funds
Investment securities
Other long-term investments	16.6
120+ days notice | Monthly | Hedge funds
Investment securities
Other long-term investments	6.8
120+ days notice | Quarterly | Hedge funds
Investment securities
Other long-term investments	9.4
120+ days notice | Semi-annual | Hedge funds
Investment securities
Other long-term investments	0
120+ days notice | Annual | Hedge funds
Investment securities
Other long-term investments	$ 0.4