Investments (Details 12) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014 item	Dec. 31, 2013
Investments [Abstract]
Threshold percentage of mortgage loans to total carrying value	5.00%all_MortgageLoansThresholdPercentage
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	100.00%	100.00%
Mortgage loans	$ 3,686	$ 4,173
Office buildings
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	25.60%	28.30%
Retail
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	24.10%	22.90%
Apartment complex
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	20.00%	19.20%
Warehouse
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	18.10%	18.60%
Other
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	12.20%	11.00%
California
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	24.80%	24.00%
Illinois
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	9.20%	9.70%
New Jersey
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	8.30%	7.20%
Texas
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	7.70%	6.30%
New York
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	6.00%	6.20%
Florida
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	4.70%	5.20%
District of Columbia
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	2.00%	5.40%
Mortgage loans, not in foreclosure
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	100.00%
Number of mortgage loans	298
Mortgage loans	3,686
Mortgage loans, not in foreclosure \| 2015
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	6.40%
Number of mortgage loans	21
Mortgage loans	236
Mortgage loans, not in foreclosure \| 2016
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	5.90%
Number of mortgage loans	27
Mortgage loans	217
Mortgage loans, not in foreclosure \| 2017
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	10.70%
Number of mortgage loans	35
Mortgage loans	395
Mortgage loans, not in foreclosure \| 2018
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	9.40%
Number of mortgage loans	30
Mortgage loans	345
Mortgage loans, not in foreclosure \| Thereafter
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	67.60%
Number of mortgage loans	185
Mortgage loans	$ 2,493

This element represents the amount of mortgage loans as a percentage of total carrying value.

No definition available.

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- Definition

The minimum percentage of mortgage loans to total carrying value that is used as a threshold for disclosure.

+ References

No definition available.

+ Details

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- Details

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- Definition

The balance represents the amount of loans that are secured by real estate mortgages, offset by the reserve to cover probable credit losses on the loan portfolio.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1(c))

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Subparagraph c

-Article 7

+ Details

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- Definition

Indicates the number of mortgages under each classification.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 10

-Section S99

-Paragraph 6

-Subparagraph (SX 210.5-04.(c) Schedule IV)

-URI http://asc.fasb.org/extlink&oid=27047687&loc=d3e5864-122674

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 948

-SubTopic 310

-Section S99

-Paragraph 1

-Subparagraph (SX 210.12-29.3)

-URI http://asc.fasb.org/extlink&oid=6589523&loc=d3e617274-123014

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph c

-Subparagraph Schedule IV

-Article 5

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 29

-Paragraph 3

-Article 12

+ Details

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