Amount of contributions made to multiemployer plan by employer.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450691-114947

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450702-114947

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 80
-Section 50
-Paragraph 5
-Subparagraph (e)(1)
-URI http://asc.fasb.org/extlink&oid=65877416&loc=SL14450657-114947

Name:	us-gaap_MultiemployerPlanContributionsByEmployer
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Benefit Plans - Pension Plan (Details) - Multi-employer plan - pension - Pentegra Defined Benefit Plan - USD ($) $ in Thousands			12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2019	Jul. 01, 2019	Jul. 01, 2018
Multiemployer Plans [Line Items]
Requisite service period			1 year
Benefit vesting period			5 years
Our plan, funded percentage				111.90%	112.50%
Period contributions	$ 302	$ 386
Common equity tier 1 capital
Multiemployer Plans [Line Items]
Company contributions to total plan contributions, percentage (not more than)			5.00%