Insurance (Rollforward of Unpaid Claims) (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Balance, beginning of period	$ 17,094	$ 16,157
Less: Reinsurance recoverables	2,198	1,968
Net balance, beginning of period	14,896	14,189
Incurred related to:
Current period	12,257	12,747
Prior periods (2)	200	24
Total incurred	12,457	12,771
Paid related to:
Current period	(8,021)	(8,709)
Prior periods	(4,146)	(3,753)
Total paid	(12,167)	(12,462)
Net balance, end of period	15,186	14,498
Add: Reinsurance recoverables	2,289	2,227
Balance, end of period (included in future policy benefits and other policy-related balances)	$ 17,475	16,725
Restatement Adjustment
Paid related to:
Net balance, end of period		(150)
Add: Reinsurance recoverables		$ 147

The amount needed to reflect the estimated ultimate cost of settling claims relating to insured events that have occurred on or before the balance sheet date, whether or not reported to the insurer at that date.

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Amount, after effects of reinsurance, of payments to settle claims incurred in the current period and related claims settlement costs.

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Amount, after effects of reinsurance, of payments to settle claims incurred in prior periods and related claims settlement costs.

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Liability as of the balance sheet date for amounts representing estimated cost of settling unpaid claims under the terms of the underlying insurance policies, less estimated reinsurance recoveries on such claims. This includes an estimate for claims which have been incurred but not reported. Claim adjustment expenses represent the costs estimated to be incurred in the settlement of unpaid claims.

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Amount, after valuation allowance, recoverable under reinsurance contracts including premium paid under reinsurance contracts. Examples include, but are not limited to, settled and unsettled claims, incurred but not reported losses, loss adjustment expense, premium paid, policy benefits and policy reserves.

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