Employee Benefit Arrangements - Expected Future Contributions and Benefit Payments (Detail) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
2013	$ 96.6
2014	97.8
2015	102.7
2016	107.2
2017	110.4
2018-2021	602.1
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
2013	4.7
2014	4.1
2015	3.7
2016	3.2
2017	2.9
2018-2021	$ 12.2

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Amount of benefits expected to be paid in the five fiscal years after the fifth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (f)

-URI http://asc.fasb.org/extlink&oid=28361610&loc=d3e1928-114920

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- Definition

Amount of benefits expected to be paid in the next fiscal year following the latest fiscal year from a defined benefit plan.

+ References

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Amount of benefits expected to be paid in the fifth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

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Amount of benefits expected to be paid in the fourth fiscal year following the latest fiscal year from a defined benefit plan.

+ References

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Amount of benefits expected to be paid in the third fiscal year following the latest fiscal year from a defined benefit plan.

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Amount of benefits expected to be paid in the second fiscal year following the latest fiscal year from a defined benefit plan.

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