Employee and Agent Benefits (Details 7) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Pension benefits
Amount recognized in statement of financial position
Amount recognized in other liabilities	$ (729.4)	$ (516.1)
Total assets (liabilities) recognized in statement of financial position	(729.4)	(516.1)
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	660.0	469.7
Prior service (benefit) cost	(30.5)	(41.6)
Pre-tax accumulated other comprehensive (income) loss	629.5	428.1
Components of Net Periodic Benefit Cost (Income)
Service cost	44.0	45.6	51.4
Interest cost	108.5	105.7	100.8
Expected return on plan assets	(114.4)	(98.4)	(79.5)
Amortization of prior service (benefit) cost	(9.7)	(10.1)	(7.7)
Recognized net actuarial (gain) loss	65.7	67.6	92.6
Amount recognized due to special events	(1.4)	(0.9)
Net periodic benefit cost (income)	92.7	109.5	157.6
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss	256.0	(27.5)
Amortization of net gain (loss)	(65.7)	(67.6)
Amortization of prior service benefit (cost)	11.1	11.0
Total recognized in pre-tax accumulated other comprehensive (income) loss	201.4	(84.1)
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	294.1	25.4
Qualified defined benefit pension plans
Amount recognized in statement of financial position
Amount recognized in other liabilities	(405.9)	(210.8)
Total assets (liabilities) recognized in statement of financial position	(405.9)	(210.8)
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	586.3	404.1
Prior service (benefit) cost	(19.2)	(26.6)
Pre-tax accumulated other comprehensive (income) loss	567.1	377.5
Components of Net Periodic Benefit Cost (Income)
Service cost	39.3	39.3
Interest cost	91.7	88.2
Expected return on plan assets	(114.4)	(98.4)
Amortization of prior service (benefit) cost	(6.5)	(6.6)
Recognized net actuarial (gain) loss	61.1	62.5
Amount recognized due to special events	(0.9)	(0.6)
Net periodic benefit cost (income)	70.3	84.4
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss	243.3	(28.4)
Amortization of net gain (loss)	(61.1)	(62.5)
Amortization of prior service benefit (cost)	7.3	7.3
Total recognized in pre-tax accumulated other comprehensive (income) loss	189.5	(83.6)
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	259.8	0.8
Nonqualified defined benefit pension plans
Amount recognized in statement of financial position
Amount recognized in other liabilities	(323.5)	(305.3)
Total assets (liabilities) recognized in statement of financial position	(323.5)	(305.3)
Amount recognized in accumulated other comprehensive (income) loss
Total net actuarial (gain) loss	73.7	65.6
Prior service (benefit) cost	(11.3)	(15.0)
Pre-tax accumulated other comprehensive (income) loss	62.4	50.6
Components of Net Periodic Benefit Cost (Income)
Service cost	4.7	6.3
Interest cost	16.8	17.5
Amortization of prior service (benefit) cost	(3.2)	(3.5)
Recognized net actuarial (gain) loss	4.6	5.1
Amount recognized due to special events	(0.5)	(0.3)
Net periodic benefit cost (income)	22.4	25.1
Other changes recognized in accumulated other comprehensive (income) loss
Net actuarial (gain) loss	12.7	0.9
Amortization of net gain (loss)	(4.6)	(5.1)
Amortization of prior service benefit (cost)	3.8	3.7
Total recognized in pre-tax accumulated other comprehensive (income) loss	11.9	(0.5)
Total recognized in net periodic benefit cost and pre-tax accumulated other comprehensive (income) loss	$ 34.3	$ 24.6