Stockholders' Equity (Summary of Components of Accumulated Other Comprehensive (Loss) Income, Net of Tax) (Parenthetical) (Details) - USD ($) $ in Millions		Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income Loss [Line Items]
Cumulative effect of adoption of new accounting standards		$ (11,125)	$ (10,111)	$ (9,958)	$ (9,594)
Accumulated other comprehensive loss transferred from 21CF, net of tax				157
Cumulative Effect Period Of Adoption Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Cumulative effect of adoption of new accounting standards	[1]				$ 0
Accounting Standards Update 2018-02 | Cumulative Effect Period Of Adoption Adjustment
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.”