Commitments and Contingencies (Details Textual) (USD $)	Jun. 30, 2012
Commitments and Contingencies (Textual) [Abstract]
Fair value of all derivative instruments with credit-risk-related contingent features	$ 616,000,000	[1]
Collateral posted by insurance operating entities	597,000,000
Impact of rating triggers on three derivative relationships	3,800,000,000
Impact of rating triggers on three derivative relationships with fair value	78,000,000
Single Notch Downgrade [Member]
Guarantor Obligations [Line Items]
Additional assets to be posted as collateral	52,000,000
Double Notch Downgrade [Member]
Guarantor Obligations [Line Items]
Additional assets to be posted as collateral	$ 64,000,000

[1] Approximately $3.6 billion and $4.0 billion of investment sales receivable that are not subject to fair value accounting are excluded as of June 30, 2012 and December 31, 2011, respectively.