Condensed Consolidated Balance Sheet (unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Common stock, par value per share (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	1,100,000,000	1,100,000,000
Common stock, shares issued (in shares)	504,133,393	501,237,055
Common stock, shares outstanding (in shares)	349,598,889	374,674,415
Treasury stock, shares (in shares)	154,534,504	126,562,640
Available-for-sale debt securities \| Available-for-sale securities
Available-for-sale securities, amortized cost	$ 32,972	$ 28,936
Held-to-maturity securities
Held-to-maturity securities, fair value	1,193	1,331
Held-to-maturity securities \| Held-to-maturity securities
Held-to-maturity securities, fair value	$ 1,193	$ 1,331

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