Investments (Details 13) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014 loan	Dec. 31, 2013
Investments
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	$ 4,188	$ 4,721
Office buildings
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	24.30%	26.50%
Apartment complex
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	23.30%	23.20%
Retail
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	22.20%	21.00%
Warehouse
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	17.80%	18.00%
Other
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	12.40%	11.30%
California
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	23.90%	23.00%
Illinois
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	9.40%	10.00%
New Jersey
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	8.00%	6.80%
Texas
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	8.00%	6.30%
New York
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	5.90%	6.00%
Florida
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	5.00%	5.70%
District of Columbia
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	2.40%	5.30%
Mortgage loans, not in foreclosure
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	100.00%
Number of mortgage loans	321
Mortgage loans	4,188
Mortgage loans, not in foreclosure \| 2015
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	5.90%
Number of mortgage loans	21
Mortgage loans	249
Mortgage loans, not in foreclosure \| 2016
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	9.50%
Number of mortgage loans	37
Mortgage loans	398
Mortgage loans, not in foreclosure \| 2017
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	10.00%
Number of mortgage loans	37
Mortgage loans	419
Mortgage loans, not in foreclosure \| 2018
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	11.00%
Number of mortgage loans	36
Mortgage loans	459
Mortgage loans, not in foreclosure \| Thereafter
Mortgage Loans on Real Estate
Percentage of mortgage portfolio carrying value	63.60%
Number of mortgage loans	190
Mortgage loans	$ 2,663

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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- 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

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