Condensed Consolidated Balance Sheet (unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 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)	504,118,452	501,237,055
Common stock, shares outstanding (in shares)	362,638,597	374,674,415
Treasury stock, shares (in shares)	141,479,855	126,562,640
Available-for-sale debt securities \| Available-for-sale securities
Debt securities, available-for-sale, amortized cost	$ 33,781	$ 28,936
Held-to-maturity securities
Held-to-maturity securities, fair value	1,173	1,331
Held-to-maturity securities \| Held-to-maturity securities
Held-to-maturity securities, fair value	$ 1,173	$ 1,331

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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