Consolidated Statements of Financial Position (Parenthetical) (USD $) In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Fixed maturities, available-for-sale	$ 50,048.1	$ 48,757.1
Fixed maturities, trading	575.3	563.1
Equity securities, trading	724.2	716.9
Other investments	2,910.4	2,944.4
Other investments measured at fair value under fair value option	133.6	142.9
Separate account assets	132,804.6	130,018.4
Separate account liabilities	132,804.6	130,018.4
Other liabilities	4,936.2	5,224.2
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	2,500.0	2,500.0
Common stock, issued (in shares)	460.9	459.3
Common stock, outstanding (in shares)	294.8	295.2
Treasury stock (in shares)	166.1	164.1
Series A
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, liquidation preference (in dollars per share)	$ 100	$ 100
Preferred stock, authorized (in shares)	3.0	3.0
Preferred stock, issued (in shares)	3.0	3.0
Preferred stock, outstanding (in shares)	3.0	3.0
Series B
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, liquidation preference (in dollars per share)	$ 25	$ 25
Preferred stock, authorized (in shares)	10.0	10.0
Preferred stock, issued (in shares)	10.0	10.0
Preferred stock, outstanding (in shares)	10.0	10.0
Aggregate consolidated variable interest entities
Fixed maturities, available-for-sale	279.5	272.0
Fixed maturities, trading	110.4	110.4
Equity securities, trading	325.5	327.2
Other investments	57.9	68.1
Separate account assets	32,652.9	32,824.7
Separate account liabilities	32,652.9	32,824.7
Other liabilities	360.2	342.4
Other liabilities measured at fair value under fair value option	$ 97.1	$ 104.9