Securities, Federal Home Loan Bank Stock (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Federal Home Loan Bank Stock [Member]
Schedule of Held-to-maturity Securities [Line Items]
Other-than-temporary impairment losses	$ 0	$ 0	$ 0	$ 0

The amount by which the fair value of an investment in debt securities categorized as Held-to-maturity is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=82896770&loc=SL6284422-111562

Name:	us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsHeldtomaturitySecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration