Stock Plans (Details Textuals) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Plans Details [Abstract]
Common shares unissued and available for grant	14	17	33
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted-average grant date fair value of RSAs granted	$ 77.8
Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights	Each stock option has an exercise price equal to the market price of the Company’s common stock on the date of grant and a contractual term of 10 years from the date of grant. Stock options generally vest 100 percent on the third anniversary of the grant date.
Intrinsic value for options exercised	$ 197	$ 51	$ 87
Proceeds From Stock Options Exercised	130	175	146
Employee Share Based Compensation Tax Benefit Realized From Exercise Of Stock Options	$ 59	4	18
Restricted Stock Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights	RSAs containing only service conditions generally vest 25 percent per year beginning with the first anniversary of the grant date. RSAs containing both service and performance conditions generally vest on the third anniversary of the grant date, and the number of shares earned depends on the achievement of predetermined Company metrics.
Total fair value of shares vested	$ 180	$ 171	$ 247
Weighted-average grant date fair value of RSAs granted	$ 77.8	$ 55.55	$ 81.99
Liability-Based Awards [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Cash paid upon vesting of PGs	$ 48	$ 41	$ 74