Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Fixed maturities, available-for-sale	$ 48,949.7	$ 49,670.8
Fixed maturities, trading	560.3	604.6
Equity securities, trading	891.8	840.2
Real estate	1,435.1	1,344.6
Other investments	3,268.0	3,209.8
Other investments measured at fair value under fair value option	55.4	127.2
Separate account assets	142,993.6	140,072.8
Long-term debt	3,315.9	2,531.2
Separate account liabilities	142,993.6	140,072.8
Other liabilities	5,463.2	5,542.2
Other liabilities measured at fair value under fair value option	$ 66.7	$ 71.0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, authorized (in shares)	2,500,000,000	2,500,000,000
Common stock, issued (in shares)	465,000,000	462,700,000
Common stock, outstanding (in shares)	294,700,000	293,900,000
Treasury stock (in shares)	170,300,000	168,800,000
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)	0	3,000,000
Preferred stock, issued (in shares)	0	3,000,000
Preferred stock, outstanding (in shares)	0	3,000,000
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)	0	10,000,000
Preferred stock, issued (in shares)	0	10,000,000
Preferred stock, outstanding (in shares)	0	10,000,000
Aggregate consolidated variable interest entities
Fixed maturities, available-for-sale	$ 269.5	$ 278.2
Fixed maturities, trading	100.4	100.4
Equity securities, trading	347.7	345.3
Real estate	343.9	284.9
Other investments	37.6	40.6
Separate account assets	34,886.5	34,655.4
Long-term debt	68.1	82.3
Separate account liabilities	34,886.5	34,655.4
Other liabilities	$ 346.5	$ 344.0