Consolidated Obligations (Narrative) (Details) - USD ($) $ in Billions	Dec. 31, 2019	Dec. 31, 2018
Schedule of Short-term and Long-term Debt [Line Items]
Obligation with Joint and Several Liability Arrangement, Amount Outstanding	$ 904.9	$ 894.5
FHLBanks [Member]
Schedule of Short-term and Long-term Debt [Line Items]
Obligation with Joint and Several Liability Arrangement, Amount Outstanding	$ 1,025.9	$ 1,031.6

Amount outstanding, before the effects of recovery, of obligation under the joint and several liability arrangement.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 405
-SubTopic 40
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=84228828&loc=SL34748401-199205

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