Investments (Past Due and Interest Accrual Status of Mortgage Loans) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Past Due and Interest Accrual Status of Mortgage Loans
Past Due Status of Mortgage Loans	$ 168	$ 135
Interest Accrual Status of Mortgage Loans	36	12
Mortgage loans that were in non accrual status	315	303
Commercial mortgage loans portfolio segment [Member]
Past Due and Interest Accrual Status of Mortgage Loans
Past Due Status of Mortgage Loans	12	12
Interest Accrual Status of Mortgage Loans	12	12
Mortgage loans that were in non accrual status	190	191
Agricultural [Member]
Past Due and Interest Accrual Status of Mortgage Loans
Past Due Status of Mortgage Loans	66	44
Interest Accrual Status of Mortgage Loans	24	0
Mortgage loans that were in non accrual status	48	47
Residential [Member]
Past Due and Interest Accrual Status of Mortgage Loans
Past Due Status of Mortgage Loans	90	79
Interest Accrual Status of Mortgage Loans	0	0
Mortgage loans that were in non accrual status	$ 77	$ 65

Recorded Investment in financing receivables that are past due at the balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7A

-URI http://asc.fasb.org/extlink&oid=28368275&loc=SL6953401-111524

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentPastDueAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Reflects the carrying amount of loans deemed to be questionable as to collection on which interest is continuing to be earned or accrued.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansAndLeasesReceivableImpairedNonperformingAccrualOfInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Reflects the carrying amount of loans deemed to be questionable as to collection on which no interest is continuing to be recognized.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=28368275&loc=d3e5111-111524

+ Details

Name:	us-gaap_LoansAndLeasesReceivableImpairedNonperformingNonaccrualOfInterest
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant