Investment Securities (Restrictions on Redemption Frequency and Advance Notice Requirements) (Details) (Hedge funds, USD $) In Millions, unless otherwise specified	Jun. 30, 2013
Investment securities
Other long-term investments	$ 115.3
Distributions from inactive hedge funds	2.5
Redemption requests	2.2
Monthly
Investment securities
Other long-term investments	5.5
Quarterly
Investment securities
Other long-term investments	76.6
Semi-annual
Investment securities
Other long-term investments	22.7
Annual
Investment securities
Other long-term investments	10.5
30-59 days notice
Investment securities
Other long-term investments	30.4
30-59 days notice | Monthly
Investment securities
Other long-term investments	0
30-59 days notice | Quarterly
Investment securities
Other long-term investments	28.7
30-59 days notice | Semi-annual
Investment securities
Other long-term investments	0
30-59 days notice | Annual
Investment securities
Other long-term investments	1.7
60-89 days notice
Investment securities
Other long-term investments	51.4
60-89 days notice | Monthly
Investment securities
Other long-term investments	0
60-89 days notice | Quarterly
Investment securities
Other long-term investments	28.7
60-89 days notice | Semi-annual
Investment securities
Other long-term investments	22.7
60-89 days notice | Annual
Investment securities
Other long-term investments	0
90-119 days notice
Investment securities
Other long-term investments	18.2
90-119 days notice | Monthly
Investment securities
Other long-term investments	0
90-119 days notice | Quarterly
Investment securities
Other long-term investments	9.6
90-119 days notice | Semi-annual
Investment securities
Other long-term investments	0
90-119 days notice | Annual
Investment securities
Other long-term investments	8.6
120+ days notice
Investment securities
Other long-term investments	15.3
120+ days notice | Monthly
Investment securities
Other long-term investments	5.5
120+ days notice | Quarterly
Investment securities
Other long-term investments	9.6
120+ days notice | Semi-annual
Investment securities
Other long-term investments	0
120+ days notice | Annual
Investment securities
Other long-term investments	$ 0.2