Equity (Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive income, net of tax	$ 2	$ 98	$ 3	$ 180
Gains on Securities
Accumulated Other Comprehensive Income Loss [Line Items]
Unrealized gains, before tax		154		283
Other comprehensive income, before tax		154		283
Unrealized gains, tax provision		(58)		(106)
Other comprehensive income, tax provision		(58)		(106)
Unrealized gains, net of tax		96		177
Other comprehensive income, net of tax		$ 96		$ 177