Accounting Pronouncements (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Change in Accounting Estimate [Line Items]
Retained earnings	$ 50,343	$ 49,423
Cumulative Effect, Period of Adoption, Adjustment \| ASU 2016-13 [Member]
Change in Accounting Estimate [Line Items]
Retained earnings		$ 59

The cumulative amount of the reporting entity's undistributed earnings or deficit.

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