Consolidated Balance Sheets (Parenthetical) (USD $) In Millions, except Share data, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Investments	$ 3,481.8	$ 947.9
Common stock, par/nominal value (in dollars per share)	$ 0.01
Series A Common Stock [Member]
Common stock, par/nominal value (in dollars per share)		$ 0.01
Common stock, authorized (in shares)		500,000,000
Common stock, issued (in shares)		142,284,430
Common stock, outstanding (in shares)		142,284,430
Class A Ordinary Shares [Member]
Common stock, par/nominal value (in dollars per share)	$ 0.01
Common stock, issued (in shares)	222,081,117
Common stock, outstanding (in shares)	222,081,117
Series B Common Stock [Member]
Common stock, par/nominal value (in dollars per share)		$ 0.01
Common stock, authorized (in shares)		50,000,000
Common stock, issued (in shares)		10,206,145
Common stock, outstanding (in shares)		10,206,145
Class B Ordinary Shares [Member]
Common stock, par/nominal value (in dollars per share)	$ 0.01
Common stock, issued (in shares)	10,147,184
Common stock, outstanding (in shares)	10,147,184
Series C Common Stock [Member]
Common stock, par/nominal value (in dollars per share)		$ 0.01
Common stock, authorized (in shares)		500,000,000
Common stock, issued (in shares)		106,402,667
Common stock, outstanding (in shares)		106,402,667
Class C Ordinary Shares [Member]
Common stock, par/nominal value (in dollars per share)	$ 0.01
Common stock, issued (in shares)	161,996,684
Common stock, outstanding (in shares)	161,996,684