Insurance (Rollforward of Unpaid Claims) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Liability for Claims and Claims Adjustment Expense [Line Items]
Balance at January 1,	$ 17,788	$ 17,094	$ 16,157
Less: Reinsurance recoverables	2,332	2,198	1,968
Net Balance at January 1,	15,456	14,896	14,189
Incurred related to:
Current year	27,093	24,571	24,370
Prior years	313	454	133
Total incurred	27,406	25,025	24,503
Paid related to:
Current year	(20,141)	(18,757)	(18,525)
Prior years	(5,882)	(5,708)	(5,271)
Total paid	(26,023)	(24,465)	(23,796)
Net Balance at December 31,	16,839	15,456	14,896
Add: Reinsurance recoverables	2,377	2,332	2,198
Balance at December 31,	$ 19,216	$ 17,788	$ 17,094

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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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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