CONDENSED CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Property and equipment, accumulated depreciation and amortization	$ 5,759	$ 5,498
Other intangible assets, accumulated amortization	$ 1,163	$ 1,092
Common stock, par value (in dollars per share)	$ 0.05	$ 0.05
Common stock, authorized shares (in shares)	262,500,000	262,500,000
Common stock, shares issued (in shares)	153,242,552	152,540,815
Common stock in treasury (in shares)	48,341,041	48,344,195