Employee and Agent Benefits (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Contributions
Contributions made by employer to fund qualified and nonqualified pension plans	$ 35.2
Pension benefits
Components of Net Periodic Benefit Cost (Income)
Service cost	16.8	$ 16.2
Interest cost	31.1	33.7
Expected return on plan assets	(36.0)	(38.7)
Amortization of prior service (benefit) cost	(0.6)	(0.6)
Recognized net actuarial (gain) loss	17.0	19.3
Net periodic benefit cost (income)	28.3	29.9
Pension benefits \| Maximum
Contributions
Amount of possible contributions to be made during the current fiscal year to the qualified and nonqualified pension plans combined	125.0
Other postretirement benefits
Components of Net Periodic Benefit Cost (Income)
Service cost		0.6
Interest cost	1.0	1.7
Expected return on plan assets	(6.9)	(8.1)
Amortization of prior service (benefit) cost	(8.6)	(5.1)
Recognized net actuarial (gain) loss		0.1
Net periodic benefit cost (income)	$ (14.5)	$ (10.8)

No definition available.

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The amount of gains or losses recognized in net periodic benefit cost.

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The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation.

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Amount of contributions made by the employer to defined benefit plans.

+ References

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-Publisher FASB
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Amount of the employer's best estimate of contributions expected to be paid to the plan in the current fiscal period.

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An amount calculated as a basis for determining the extent of delayed recognition of the effects of changes in the fair value of assets. The expected return on plan assets is determined based on the expected long-term rate of return on plan assets and the market-related value of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The increase in a defined benefit pension plan's projected benefit obligation or a defined benefit postretirement plan's accumulated postretirement benefit obligation due to the passage of time.

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The total amount of net periodic benefit cost for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) due to settlements or curtailments.

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The actuarial present value of benefits attributed by the pension benefit formula to services rendered by employees during the period. The portion of the expected postretirement benefit obligation attributed to employee service during the period. The service cost component is a portion of the benefit obligation and is unaffected by the funded status of the plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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