Reinsurance - Guaranteed Minimum Death Benefit Contracts (Details) (Variable Annuity [Member], Guaranteed Minimum Death Benefit [Member], USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2013	Dec. 31, 2012
Variable Annuity [Member] \| Guaranteed Minimum Death Benefit [Member]
Guaranteed Minimum Death Benefits Reserves [Line Items]
Future Policy Benefit Reserve, beginning balance, gross	$ 1,090	$ 1,170
Claims payable, beginning balance, gross	24	40
Less: Reinsurance and other amounts recoverable	42	53
Balance at January 1, net	1,072	1,157
Add: Incurred benefits	702	17
Less: Paid benefits (including $1,647 premium for Berkshire)	1,672	102
Ending balance, net	102	1,072
Claims payable, ending balance, gross	23	24
Add: Reinsurance and other amounts recoverable	1,371	42
Future Policy Benefit Reserve, ending balance, gross	$ 1,450	$ 1,090

Amount of guaranteed minimum benefit payments to policyholders and contract holders, during the period presented, resulting in a decrease to the liability for expected guaranteed minimum benefits in excess of projected account values.

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Amount of expected guaranteed benefits in excess of the projected account balances for minimum guaranteed benefit contracts, as of the balance sheet date.

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- Definition

Amount of guaranteed minimum benefit expense incurred during the period presented, resulting in an increase to the liability for expected guaranteed minimum benefits in excess of projected account values.

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- Definition

Amount of guaranteed minimum benefits the ceding insurer expects to recover on insurance policies ceded to other insurance entities as of the balance sheet date.

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- Definition

The estimated cost of settling claims under the terms of the underlying insurance policies and assumed and ceded insurance contracts as of the balance sheet date, including an estimate for claims which have been incurred but not reported and the actual and estimated costs of settling claims.

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