Equity (Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 24,039
Income tax benefit (expense)	138	$ (1,944)
Ending balance	22,600
Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(536)	(564)
Change in OCI before reclassifications	(298)	(109)
Amounts reclassified from AOCI	3	5
Income tax benefit (expense)	(25)	(3)
Ending balance	(856)	(671)
Net Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	28,112	14,745
Change in OCI before reclassifications	(808)	8,564
Amounts reclassified from AOCI	(546)	(275)
Income tax benefit (expense)	179	(1,926)
Ending balance	26,937	21,115
Pension and Postretirement Unrecognized Net Periodic Benefit (Cost)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(3,537)	(3,275)
Change in OCI before reclassifications	2	4
Amounts reclassified from AOCI	70	60
Income tax benefit (expense)	(16)	(15)
Ending balance	(3,481)	(3,226)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	24,039	10,906
Change in OCI before reclassifications	(1,104)	8,459
Amounts reclassified from AOCI	(473)	(210)
Income tax benefit (expense)	138	(1,944)
Ending balance	22,600	17,218
Cash flow hedges \| Net Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	832	811
Ending balance	$ 3,186	776
ASU 2017-12 \| Foreign Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect of adoption		0
ASU 2017-12 \| Net Unrealized Investment Gains (Losses)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect of adoption		7
ASU 2017-12 \| Pension and Postretirement Unrecognized Net Periodic Benefit (Cost)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect of adoption		0
ASU 2017-12 \| Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Cumulative effect of adoption		$ 7

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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Represents the quantification of the effect of adopting the new accounting standard or change in accounting principle expected by the entity to have a significant effect on the entity's financial statements.

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Amount before tax and reclassification adjustments of other comprehensive income (loss).

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