Stockholders' Equity - Stock Repurchases (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2021	Mar. 31, 2021
Stockholders' Equity and Stock-based Compensation Disclosure [Abstract]
Common stock authorized to be repurchased			$ 5,000
Stock repurchased (in shares)	180,845	1,182,410
Repurchases of common stock to be held as treasury stock	$ 100	$ 600
Remaining authorized repurchase amount	$ 4,400	$ 4,400

Equity impact of the cost of common and preferred stock that were repurchased during the period. Recorded using the cost method.

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