Taxes on Income - Tax reform estimates (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	12 Months Ended
Dec. 31, 2017	Jun. 30, 2018	Dec. 31, 2017
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
Effective income tax rate		21.00%
Provisional increase of transition tax expense			$ 31

Percentage of domestic federal statutory tax rate applicable to pretax income (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB TOPIC 6.I)
-URI http://asc.fasb.org/extlink&oid=34349781&loc=d3e330036-122817

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 13
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32698-109319

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