Employee and Agent Benefits (Details) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Pension benefits
Components of Net Periodic Benefit Cost (Income)
Service cost	$ 10.7	$ 11.4	$ 32.5	$ 34.2
Interest cost	27.3	26.4	81.3	79.2
Expected return on plan assets	(29.7)	(24.6)	(87.2)	(73.8)
Amortization of prior service (benefit) cost	(2.4)	(2.5)	(7.4)	(7.5)
Recognized net actuarial (gain) loss	14.0	16.9	43.0	50.7
Amount recognized due to special events	(0.3)		(1.0)
Net periodic benefit cost (income)	19.6	27.6	61.2	82.8
Other postretirement benefits
Components of Net Periodic Benefit Cost (Income)
Service cost	0.3	2.8	0.9	8.4
Interest cost	2.3	5.3	6.7	15.9
Expected return on plan assets	(8.8)	(7.5)	(26.1)	(22.5)
Amortization of prior service (benefit) cost	(7.3)	(0.5)	(22.1)	(1.5)
Recognized net actuarial (gain) loss	0.1	1.2	0.3	3.6
Amount recognized due to special events	(1.1)		(4.0)
Net periodic benefit cost (income)	$ (14.5)	$ 1.3	$ (44.3)	$ 3.9