Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Period Type:	duration

Share Repurchases (Narrative) (Details) - USD ($) $ in Billions	Oct. 31, 2017	Oct. 09, 2017
Two Thousand And Seventeen Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Share repurchase program, authorized amount		$ 20.0
Two Thousand And Fifteen Share Repurchase Program [Member]
Equity, Class of Treasury Stock [Line Items]
Stock repurchase program, remaining authorized repurchase amount	$ 2.6