Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	100,000	100,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	3,200,000,000	3,200,000,000
Common stock, shares issued (in shares)	1,733,000,000	1,727,000,000
Common stock, shares outstanding (in shares)	1,310,000,000	1,302,000,000
Treasury stock (in shares)	423,000,000	425,000,000