Taxes on Income - Tax reform estimates (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2017	Mar. 31, 2018	Jan. 02, 2018
Effect of Tax Cuts and Jobs Act
Income tax expense for the estimated impact of the Tax Act adjustments	$ 83
Provisional increase of tax expense, change in tax rate effect on tax asset position	52
Provisional increase of transition tax expense	31
Retained Earnings (Accumulated Deficit)	$ 4,987	$ 5,114	$ 5,024