Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Loss Contingencies [Line Items]
The FHLBank's outstanding consolidated obligations for which the Bank is jointly and severally liable	$ 907,877	$ 886,081
Other liabilities	292	207
Standby Letters of Credit [Member]
Loss Contingencies [Line Items]
Other liabilities	$ 80	$ 102

Amount of liabilities classified as other.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Name:	us-gaap_OtherLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant