Stockholders' Equity (Summary of Components of Accumulated Other Comprehensive (Loss) Income, Net of Tax) (Parenthetical) (Details) - USD ($) $ in Millions		Jun. 30, 2019	Jul. 01, 2018	Jun. 30, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Cumulative effect of adoption of new accounting standards	[1]			$ 0
Accumulated other comprehensive loss transferred from 21CF, net of tax		$ 157
Unrealized Holding Gains on Securities | Accounting Standards Update 2016-01
Accumulated Other Comprehensive Income Loss [Line Items]
Cumulative effect of adoption of new accounting standards			$ 130
Benefit Plan Adjustments and Other | Accounting Standards Update 2018-02
Accumulated Other Comprehensive Income Loss [Line Items]
Cumulative effect of adoption of new accounting standards			$ 13

[1] Reflects the adoption of ASU 2016-01 and ASU 2018-02 as defined in Note 11—Stockholders’ Equity under the heading “Accumulated other comprehensive (loss) income.”