Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Fixed maturities, available-for-sale	$ 53,045.4	$ 49,966.5
Fixed maturities, trading	687.5	686.8
Equity securities, available-for-sale	103.7	104.5
Equity securities, trading	1,262.0	1,202.7
Real estate	1,486.6	1,451.8
Other investments	4,023.9	3,251.7
Other investments measured at fair value under fair value option	75.6	53.4
Separate account assets	132,325.9	136,978.9
Contractholder funds	36,660.5	35,716.1
Long-term debt	3,269.1	3,265.2
Separate account liabilities	132,325.9	136,978.9
Other liabilities	5,971.6	5,678.4
Redeemable noncontrolling interest	$ 260.9	$ 85.7
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)	468,100,000	466,200,000
Common stock, outstanding (in shares)	290,400,000	291,400,000
Treasury stock (in shares)	177,700,000	174,800,000
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	0
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	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)	0	0
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Aggregate consolidated variable interest entities
Fixed maturities, available-for-sale	$ 231.7	$ 257.4
Fixed maturities, trading	100.4	100.4
Equity securities, trading	666.9	640.9
Real estate	391.9	354.5
Other investments	285.0	29.5
Separate account assets	35,356.5	33,300.4
Contractholder funds	339.5	338.9
Long-term debt	46.0	42.8
Separate account liabilities	35,356.5	33,300.4
Other liabilities	322.7	345.9
Other liabilities measured at fair value under fair value option	73.1	$ 68.1
Redeemable noncontrolling interest	$ 195.6