Investments (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended			6 Months Ended		12 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Common Stock	Jun. 30, 2013 Common Stock	Dec. 31, 2012 Common Stock	Dec. 31, 2013 Common Stock	Jun. 30, 2014 Cost method and other investments	Dec. 31, 2013 Cost method and other investments	Jun. 30, 2014 Private Equity Funds	Dec. 31, 2013 Private Equity Funds	Jun. 30, 2014 Available-for-sale securities	Dec. 31, 2013 Available-for-sale securities	Jun. 30, 2014 Available-for-sale securities State Street Corporation	Dec. 31, 2013 Available-for-sale securities State Street Corporation	Jun. 30, 2014 Available-for-sale securities Other available-for-sale securities	Dec. 31, 2013 Available-for-sale securities Other available-for-sale securities	Jun. 30, 2014 Other investments	Dec. 31, 2013 Other investments	Jun. 30, 2014 Other investments Trading securities	Dec. 31, 2013 Other investments Trading securities	Jun. 30, 2014 Other investments Cost method and other investments	Dec. 31, 2013 Other investments Cost method and other investments
Investments
Carrying Value	$ 766.0		$ 766.0		$ 881.3					$ 14.5	$ 15.7	$ 147.8	$ 167.3	$ 574.0	$ 654.0	$ 432.1	$ 515.5	$ 141.9	$ 138.5	$ 192.0	$ 227.3	$ 29.7	$ 44.3	$ 162.3	$ 183.0
Deferred Tax Liabilities, Other														172.0	201.1
Available-for-sale securities
Book cost basis	168.3		168.3		166.9
Available-for-sale Securities, Gross Unrealized Gain, Accumulated Investments	406.6		406.6		487.5
Available-for-sale Securities, Gross Unrealized Loss, Accumulated Investments	(0.9)		(0.9)		(0.4)
Market value	574.0		574.0		654.0
Proceeds from sale of investments			86.7	148.1
Gross realized gains	2.1	16.4	48.2	85.5
Gross realized losses	0.2	0.7	0.3	1.1
Unrealized losses related to other than temporary investment impairments	0	0.3	0.1	0.5
Fair value of investments by the length of time that the securities have been in a continuous loss position
Less than 12 months						13.4			5.9
Total						13.4			5.9
Unrealized losses of investments by the length of time that the securities have in a continuous loss position
Less than 12 months						0.9	0.4
Total						0.9	0.4
Available-for-sale Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value						0		0
Available-for-sale Securities, Continuous Unrealized Loss Position, 12 Months or Longer, Aggregate Loss						0		0
Other than Temporary impairment
Lower of cost or market valuation adjustments on cost method investments	1.3	0	1.6	0.3
Future capital commitments
Future capital commitments related to private equity fund investments												6.5
Investment Income, Dividend										33.2
Cost-method Investments, Realized Gain (Loss)	$ 103.6