Mortgage Loans Held for Portfolio Other Delinquency Statistics table (Details) - USD ($) $ in Thousands		Sep. 30, 2020	Dec. 31, 2019
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage Loans in Process of Foreclosure, Amount	[1]	$ 12,898	$ 5,850
Loans and Leases Receivable, Serious Delinquencies Ratio	[2]	2.40%	0.30%
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 7,893	$ 3,363
Financing Receivable, Nonaccrual	[3]	123,935	14,890
Government-guaranteed/insured loans
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage Loans in Process of Foreclosure, Amount	[1]	$ 3,026	$ 1,110
Loans and Leases Receivable, Serious Delinquencies Ratio	[2]	5.70%	1.90%
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 7,893	$ 3,363
Financing Receivable, Nonaccrual	[3]	0	0
Conventional MPF Loan [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Mortgage Loans in Process of Foreclosure, Amount	[1]	$ 9,872	$ 4,740
Loans and Leases Receivable, Serious Delinquencies Ratio	[2]	2.30%	0.30%
Financing Receivable, 90 Days or More Past Due, Still Accruing		$ 0	$ 0
Financing Receivable, Nonaccrual	[3]	$ 123,935	$ 14,890

[1] Includes loans where the decision of foreclosure or similar alternative such as pursuit of deed-in-lieu has been reported. Loans in process of foreclosure are included in past due or current loans dependent on their delinquency status.

[2] Loans that are 90 days or more past due or in the process of foreclosure expressed as a percentage of the total loan portfolio class.

[3] All conventional mortgage loans on non-accrual status had an associated ACL or available credit enhancements to absorb expected credit losses.