Fair Values Carrying Value and Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands		Dec. 31, 2019		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks		$ 69,416		$ 10,431
Trading securities		2,250,264		163,038
Available-for-sale securities Fair Value		7,409,000		5,849,944
Held-to-maturity securities	[1],[2]	871,107		1,295,023
Held-to-maturity securities Fair Value		1,035,410		1,528,929
Accrued interest receivable		112,163		112,751
Derivative assets		159,731		22,403
Derivative Assets, Netting Adjustments and Cash Collateral	[3],[4]	144,402		8,571
Mandatorily redeemable capital stock		(5,806)		(31,868)	$ (35,923)	$ (32,687)
Accrued interest payable		(104,477)		(112,043)
Derivative liabilities		(10,271)		(255,800)
Derivative liability, Netting Adjustments and Cash Collateral	[3],[4]	33,534		53,752
Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks		69,416		10,431
Interest-bearing deposits		1,253,873		593,199
Securities purchased under agreements to resell		0		0
Federal funds sold		0		0
Trading securities	[5]	0		0
Available-for-sale securities Fair Value	[5]	0		0
Held-to-maturity securities Fair Value		0		0
Advances		0		0
Mortgage loans, net		0		0
Accrued interest receivable		0		0
Derivative assets		0	[5]	0
Other assets	[5]	13,894		9,988
Deposits		0		0
Mandatorily redeemable capital stock		(5,806)		(31,868)
Accrued interest payable		0		0
Derivative liabilities	[5]	0		0
Level 1 [Member] | Commitments to make additional advances [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other		0		0
Level 1 [Member] | Standby Letters of Credit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other		0		0
Level 1 [Member] | COs - Discount notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CO Discount notes		0		0
Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks		0		0
Interest-bearing deposits		0		0
Securities purchased under agreements to resell		3,500,003		6,499,078
Federal funds sold		859,999		1,500,002
Trading securities	[5]	2,250,264		163,038
Available-for-sale securities Fair Value	[5]	7,344,348		5,800,343
Held-to-maturity securities Fair Value		456,942		638,164
Advances		34,735,775		43,167,700
Mortgage loans, net		4,615,737		4,217,487
Accrued interest receivable		112,163		112,751
Derivative assets		15,329	[5]	13,832
Other assets	[5]	18,045		15,071
Deposits		(674,269)		(474,848)
Mandatorily redeemable capital stock		0		0
Accrued interest payable		(104,477)		(112,043)
Derivative liabilities	[5]	(43,805)		(309,552)
Level 2 [Member] | Commitments to make additional advances [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other		(3,884)		(4,164)
Level 2 [Member] | Standby Letters of Credit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other		(1,723)		(1,257)
Level 2 [Member] | COs - Discount notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CO Discount notes		(27,681,470)		(33,062,585)
Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks		0		0
Interest-bearing deposits		0		0
Securities purchased under agreements to resell		0		0
Federal funds sold		0		0
Trading securities	[5]	0		0
Available-for-sale securities Fair Value	[5]	64,652		49,601
Held-to-maturity securities Fair Value		578,468		890,765
Advances		0		0
Mortgage loans, net		18,404		20,600
Accrued interest receivable		0		0
Derivative assets		0	[5]	0
Other assets	[5]	0		0
Deposits		0		0
Mandatorily redeemable capital stock		0		0
Accrued interest payable		0		0
Derivative liabilities	[5]	0		0
Level 3 [Member] | Commitments to make additional advances [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other		0		0
Level 3 [Member] | Standby Letters of Credit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other		0		0
Level 3 [Member] | COs - Discount notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CO Discount notes		0		0
Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks		69,416		10,431
Interest-bearing deposits		1,253,873		593,199
Securities purchased under agreements to resell		3,500,000		6,499,000
Federal funds sold		860,000		1,500,000
Trading securities	[5]	2,250,264		163,038
Available-for-sale securities Fair Value	[5]	7,409,000		5,849,944
Held-to-maturity securities		871,107		1,295,023
Advances		34,595,363		43,192,222
Mortgage loans, net		4,501,251		4,299,402
Accrued interest receivable		112,163		112,751
Derivative assets		159,731	[5]	22,403
Other assets	[5]	31,939		25,059
Deposits		(674,309)		(474,878)
Mandatorily redeemable capital stock		(5,806)		(31,868)
Accrued interest payable		(104,477)		(112,043)
Derivative liabilities	[5]	(10,271)		(255,800)
Carrying Value [Member] | Commitments to make additional advances [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other		0		0
Carrying Value [Member] | Standby Letters of Credit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other		(1,723)		(1,257)
Carrying Value [Member] | COs - Discount notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CO Discount notes		(27,681,169)		(33,065,822)
Total Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks		69,416		10,431
Interest-bearing deposits		1,253,873		593,199
Securities purchased under agreements to resell		3,500,003		6,499,078
Federal funds sold		859,999		1,500,002
Trading securities	[5]	2,250,264		163,038
Available-for-sale securities Fair Value	[5]	7,409,000		5,849,944
Held-to-maturity securities Fair Value		1,035,410		1,528,929
Advances		34,735,775		43,167,700
Mortgage loans, net		4,634,141		4,238,087
Accrued interest receivable		112,163		112,751
Derivative assets		159,731	[5]	22,403
Other assets	[5]	31,939		25,059
Deposits		(674,269)		(474,848)
Mandatorily redeemable capital stock		(5,806)		(31,868)
Accrued interest payable		(104,477)		(112,043)
Derivative liabilities	[5]	(10,271)		(255,800)
Total Fair Value [Member] | Commitments to make additional advances [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other		(3,884)		(4,164)
Total Fair Value [Member] | Standby Letters of Credit [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Other		(1,723)		(1,257)
Total Fair Value [Member] | COs - Discount notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CO Discount notes		(27,681,470)		(33,062,585)
COs - bonds [Member] | Level 1 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CO Bonds		0		0
COs - bonds [Member] | Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CO Bonds		(24,226,123)		(25,843,163)
COs - bonds [Member] | Level 3 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CO Bonds		0		0
COs - bonds [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CO Bonds		(23,888,493)		(25,912,684)
COs - bonds [Member] | Total Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
CO Bonds		$ (24,226,123)		$ (25,843,163)

[1] Carrying value of held-to-maturity securities represents the sum of amortized cost and the amount of noncredit-related other-than-temporary impairment recognized in accumulated other comprehensive loss.

[2] Fair values of held-to-maturity securities were $1,035,410 and $1,528,929 at December 31, 2019 and 2018, respectively.

[3] Amounts represent the effect of master-netting agreements intended to allow us to settle positive and negative positions with the same counterparty. Cash collateral and related accrued interest posted was $178.5 million and $62.8 million at December 31, 2019, and 2018, respectively. The change in cash collateral posted is included in the net change in interest-bearing deposits in the statement of cash flows. Cash collateral and related accrued interest received was $561 thousand and $471 thousand at December 31, 2019 and 2018.

[4] These amounts represent the effect of master-netting agreements intended to allow us to settle positive and negative positions and also cash collateral and related accrued interest held or placed with the same clearing member and/or counterparty.

[5] Carried at fair value and measured on a recurring basis.