Investments (Related Party Investment Transactions) (Details) (Affiliated Entity [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Affiliated Entity [Member]
Invested Assets Transferred To and From Affiliates
Estimated fair value of invested assets transferred to affiliates	$ 0	$ 0	$ 13	$ 0
Amortized cost of assets transferred to affiliates	0	0	12	0
Net investment gains (losses) recognized on transfers	0	0	1	0
Estimated fair value of invested assets transferred from affiliates	$ 77	$ 0	$ 83	$ 0

Difference between the sale price and the carrying value when a financial asset transferred in a securitization, asset-backed financing arrangement, or similar transfer is accounted for as a sale, including those transactions in which the seller or transferor has continuing involvement with the financial assets that have been transferred.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=13989330&loc=d3e107207-111719

Name:	us-gaap_GainLossFromSaleOfFinancialAssetsInSecuritizationsOrAssetBackedFinancingArrangement
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration