Cover Page - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Feb. 29, 2020	Jun. 30, 2019
Entity Information [Line Items]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2019
Document Transition Report	false
Entity File Number	000-51402
Entity Registrant Name	FEDERAL HOME LOAN BANK OF BOSTON
Entity Tax Identification Number	04-6002575
Entity Address, Address Line One	800 Boylston Street,
Entity Address, City or Town	Boston
Entity Address, State or Province	MA
City Area Code	(617)
Local Phone Number	292-9600
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Amendment Flag	false
Entity Central Index Key	0001331463
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Entity Address, Postal Zip Code	02199
Entity Public Float			$ 0
Entity Incorporation, State or Country Code	X1
Common Class A [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		0
Common Class B [Member]
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		20,758,802