CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 919	$ 796	$ 1,699	$ 4,361
Other comprehensive income (loss), net of tax (benefit) expense:
Retirement benefits, net of tax	13	39	9	33
Long-term investments, net of tax		4		3
Hedging instruments, net of tax				11
Cumulative translation adjustment and other, net of tax	11	(5)	14	17
Comprehensive income	$ 943	$ 834	$ 1,722	$ 4,425