Commitments and Contingencies (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2020	Dec. 31, 2019
Loss Contingencies [Line Items]
Off-balance Sheet Risks, with annual renewal option		$ 4,900,000	$ 4,300,000
Other Liabilities - Standby Letter of Credit Fees		$ 76,388	64,736
Maximum Commitment Period		60 days
Open RepoPlus Advance Product
Loss Contingencies [Line Items]
Open Repo Plus Product Outstanding		$ 12,300,000	9,800,000
Maximum
Loss Contingencies [Line Items]
Letter of Credit Renewal Period		5 years
Standby Letters of Credit Issuance Commitments [Member]
Loss Contingencies [Line Items]
Total		$ 461,200	23,900
Standby letters of credit outstanding (1) (2)
Loss Contingencies [Line Items]
Expiration Date Within One Year		19,605,400
Expiration Date After One Year		0
Total	[1],[2]	19,605,400	17,370,617
Other Liabilities - Standby Letter of Credit Fees		3,000	3,500
Commitments to fund additional advances and BOB loans
Loss Contingencies [Line Items]
Expiration Date Within One Year		1,643
Expiration Date After One Year		0
Total		1,643	19,796
Commitments to purchase mortgage loans | Mortgage Receivable [Member]
Loss Contingencies [Line Items]
Expiration Date Within One Year		68,027
Expiration Date After One Year		0
Total		68,027	73,574
Unsettled consolidated obligation bonds, at par
Loss Contingencies [Line Items]
Expiration Date Within One Year		39,000
Expiration Date After One Year		0
Total		39,000	62,000
Unsettled consolidated obligation discount notes, at par [Member]
Loss Contingencies [Line Items]
Expiration Date Within One Year		65,000
Expiration Date After One Year		0
Total		$ 65,000	$ 1,083,406

[1] Excludes approved requests to issue future standby letters of credit of $461.2 million and $23.9 million at September 30, 2020 and December 31, 2019, respectively.

[2] Letters of credit in the amount of $4.9 billion and $4.3 billion at September 30, 2020 and December 31, 2019, respectively, have renewal language that permits the letter of credit to be renewed for an additional period with a maximum renewal period of approximately 5 years.