Unaudited Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Billions	Sep. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
PROPERTY AND EQUIPMENT, accumulated depreciation	$ 1.2	$ 1.1
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock authorized (in shares)	5,000,000	5,000,000
Preferred stock issued (in shares)	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock authorized (in shares)	1,500,000,000	1,500,000,000
Common stock issued (in shares)	120,562,149	120,562,149
Treasury stock (in shares)	29,317,911	19,909,940